Case statement in where clause oracle performance. This will lag your query. I get 10k IDs from DB-A and need to get data from DB-B for each one. A simple boolean or is equivalent. Mar 9, 2006 · Here is an example of the query: SELECT. Jun 21, 2018 · E. column2 = b. Here is a case where an index is being used (and the function is not evaluated for every row): Jun 19, 2010 · I tried it with Oracle, and it was exactly the same. LEFT OUTER JOIN Table2 Table2 ON ( CASE WHEN Table1. Here, we explore the syntax, types, and practical use cases of the PL/SQL CASE statement to make better decisions and improve your ability to use conditional logic in Oracle Feb 18, 2014 · Nice. Any help would be great in knowing if this type of statement is possible. This comprehensive guide will explore the syntax, use cases, and practical Dec 3, 2014 · You just need to make both comparisons in the same case statement: and dep_dt = case when to_char( SysDate, 'D' ) <> '2' and dep_dt <= SysDate then dep_dt else SysDate end Jun 16, 2011 · Here's another way of writing it which may address concerns about accessing the second table more times than necessary. Apr 24, 2007 · Case construct with WHERE clause Hi Tom, I have a question and I don't know if this is possible or if i'm jsut doing something wrong because i get multiple errors like missing right paren, or missing keyword. Thanks for accepting this as the answer but Tony Andrews solution is a lot more straightforward and, in my view, the better answer. BusinessId) BEGIN SELECT * FROM dbo. CASE expressions found in SELECT list are CPU-intensive operations. 5 6 b) If a <result> specifies a <value expression>, then its value 7 is the value of that <value expression>. index_id = p. ELSE 'Other Traffic' END AS ORGANIZATION, Complex CASE expressions can affect query performance in multiple ways. orderid = CASE WHEN @orderid > 0 then @orderid ELSE orders. index_id JOIN sys. You select only the records where the case statement results in a 1. column1 when b. ACCOUNT = 545 AND A. The Decode operation is done at storage Server level where the data is present BUT CASE is done at DB Instance level which receives data from DB storage Level. WHEN op. Please suggest what may be done to improve its performance: Query: Sep 24, 2015 · The ordered_predicates hint is specified in the Oracle WHERE clause of a query and is used to specify the order in which Boolean predicates should be evaluated. Hot Network Questions Nov 20, 2015 · Both solutions works well. ColumnName != '') OR (pEntityName IS NOT NULL AND e. Aug 20, 2018 · If I remove the CASE statement from WHERE clause and pass something like where col1=p_field1) the index is used and the query performance is very good. The CASE statement in Oracle isn't a function, so I haven't labelled it as one. ol. hobt_id THEN 1 WHEN a. Select CASE SQL To add to Alex's answer: The CASE expression has two forms, the "simple" CASE expression and the "searched" CASE expression. Case statement in where. Forget performance for a minute. Below is query I am trying to make work using a case statement Dec 30, 2008 · In my case the IDs come from a separate database. Use table aliases that are abbreviations for the table names. Technical questions should be asked in the appropriate category. CASE expressions in WHERE clause (filter and join predicates) may result in incorrect join cardinality estimate and miscalculating the costs. OrganizationLevelLabel AS ORG_LEVEL, CASE WHEN op. 438932 Apr 14 2008 — edited Apr 14 2008. allocation_units a ON CASE WHEN a. Oct 1, 2024 · SQL CASE Statement Basics. Apr 21, 2020 · The ranges set out in the case statement all differ, with no discernible pattern between them. Table1 Table1. Note: same CASE statement is used in PL/SQL blocks. Technical questions should be asked in the appropriate category. ColumnName = pEntityName); May 17, 2013 · SELECT STATEMENT INLIST ITERATOR INDEX RANGE SCAN This seems to imply that when you have an IN list and are using this with a PK column, Oracle keeps the list internally as an "INLIST" because it is more efficient to process this, rather than converting it to ORs as in the case of an un-indexed table. What is the best scenario?a) SELECT () WHERE @var = 0 or May 28, 2017 · Although the documentation says "The CASE statement is more readable and more efficient. This would speed the 'report' up -- perhaps to well under 1 second. Oracle SQL doesn't support a boolean data type, though, so the expression is invalid. ", I didn't find a significant difference between three styles of conditionals. Thanks! – Oct 30, 2017 · Here is the query that you can use. Description, Employee. CASE statements can be used in different SQL clauses like SELECT, UPDATE, INSERT, WHERE, ORDER BY, and more depending on the Oracle SQL CASE statement gives you the flexibility to use sql IF ELSE logic in a SELECT, WHERE and JOIN clause. partitions p ON i. Do it and see what the DBMS thinks of the plan for this query. CASE with Conditional Aggregation. i. In the end, the subquery in the simple CASE expression was evaluated 4 times. Instead, use AND and OR:. Actually I am passing a value in a procedure according to the value i have to select fields in where clause. value into #t from a inner join b on a. ,1000) statement. May 12, 2011 · The subquery in the IN clause does not depend on anything in the outer query. column1 like 'DEDUCTABLE%' May 26, 2016 · I believe that a CASE statement can only return one value (corresponding to one column in the result set). Here is what I have so far but I know I'm going down the wrong path; where. D_OrganizationID = 0 THEN 'Unknown Consumer'. The SQL CASE statement within aggregation functions allows conditionally aggregating data based on certain criteria. 4 Common Pitfalls and Solutions With SQL CASE Statements. CASE expressions require that they be evaluated in the order that they are defined. Compare and contrast the CASE WHEN statement with the IF statement in SQL. for example. COMPARE_TYPE = 'A' AND T1. COL1 ELSE SELECT A1. SELECT count(*) FROM userTable WHERE ( CASE WHEN mac IS NULL THEN mac IS NULL ELSE mac = '000fe95erd32' END ) your clause is not well good. COL1 THEN SELECT A1. 3 WHEN 'B' THEN 3 WHEN 'B-' THEN 2. If there is no ELSE part and no conditions are true, it returns NULL. column1 like 'DEDUCTABLE%' Aug 5, 2022 · That means you want the result of the CASE expression to be a boolean. you can do it differently like this : Mar 15, 2021 · Is it possible to use a SELECT statement within case For ex, SELECT CASE WHEN A1. EmployeeName, Employee. TableName e WHERE (pEntityName IS NULL AND e. In that blog, we employed the Case Statement as most DBAs and developers do, in the SELECT clause. The HAVING clause restricted the products to those that were CPU (category id 1) with the number of products greater than 5 and Video Card (category id 2) with the number of products greater than 2. 7 WHEN 'D+' THEN 1. COL1=C1. So, it does not matter if you use WHERE or HAVING in your query. At least for built-in functions, Oracle should be able to figure out that it could evaluate it only once. If I replace them with case will it work faster? For example; select case sum(nvl(birikim,0)) when null then 0 else sum(nvl(birikim,0) end Next, let’s go over some common pitfalls when working with SQL CASE statements so that you can improve your code quality. Another option is dynamic SQL, where you actually create a string with the SQL statement and then execute it. I have a table with the below data, SELECT DEPT_NO, DEPT_NAME FROM SORTNG_LOGIC; DEPT_NO DEPT_NAME Jun 9, 2011 · My query has been modified to use a CASE statement in the WHERE clause to consider data from certain columns based on a parameter value. g. Having issue with the following I know CASE statements in WHEREs are allowed just can't get it working for this one. There are a number of examples using the CASE WHEN construct in SQL, such as the SELECT columns or in ORDER BY clauses, but we tend to forget CASE can be used wherever an expression is expected. Thanks – ronan Jun 3, 2009 · For appeals, questions and feedback about Oracle Forums, please email oracle-forums-moderators_us@oracle. CREATE TABLE performance_test AS ( SELECT * FROM dba_objects ); SELECT * FROM performance_test WHERE object_name IN ('DBMS_STANDARD', 'DBMS_REGISTRY', 'DBMS_LOB' ); Even though the query uses IN, the Execution Plan says that it uses OR: May 17, 2023 · Alternatives to CASE. This scenario can almost always be rewritten to improve performance. That's the one we'll compare against. Jan 11, 2016 · I am facing difficulty in understanding oracle(12c) sql order by clause with case statement. – Oct 19, 2017 · Lose the "distinct". What is the best scenario? a) SELECT () WHERE @var = 0 or table. GRP_ID = CASE ? WHEN 0 THEN A. SUM(NVL()) is not needed, because NULL values are ignored. However, my CASE expression needs to check if a field IS NULL. Jul 11, 2013 · How to use case statement inside where clause in oracle? 1. Jun 8, 2016 · My query has a CASE statement within the WHERE clause that takes a parameter, and then executing a condition based on the value entered. The CASE statement in SQL evaluates conditions and returns a result when the first condition equates to true: CASE WHEN condition1 THEN result1 WHEN condition2 THEN result2 ELSE resultN END. I want to use as: when pcustomer_id IS NULL then WHERE c. Case expression in where clause in Oracle. In a "simple" CASE expression you compare one expression to one or more values; that doesn't work with NULL, as we know from the first week of SQL classes. id = c. Orders AS ORD ON CUS. As you're checking whether the result of the case statement is the same as the ELSE clause then the statement is the same as the opposite of all other conditions. with bank_details as (Select 1 bank_id, 'First Bank' bank_name, 'N' auto_dep_flag from dual union all Select 2 bank_id, 'Deposit Bank' bank_name, 'Y' auto_dep_flag from dual union all Select 3 bank_id, 'Cash Transaction' bank_name, 'N' auto_dep_flag from dual ) select bank_name from A REGEXP_LIKE will do a case-insensitive regexp search. If you want to find all the exam results with A or B grades, you can place the select above in a subquery. Answer: Unlike the IF statement, CASE WHEN is SQL’s standard conditional construct and provides a more readable and flexible solution for handling multiple conditions. Apr 2, 2020 · Case construct with WHERE clause Hi Tom, I have a question and I don't know if this is possible or if i'm jsut doing something wrong because i get multiple errors like missing right paren, or missing keyword. May 22, 2021 · There is a major, major difference between using a CASE expression and boolean expressions in the WHERE clause. I've tried this: Jun 2, 2023 · You can’t reference the CASE statement like the example you gave, because it’s referring to a column alias, which can’t be done inside a WHERE clause. And if the end date is empty, it should not filter on it. CustomerID AND CUS. Jan 29, 2014 · According to Oracle's documentation linked to in the answer, "To write a query that performs an outer join of tables A and B and returns all rows from A (a left outer join), use the LEFT [OUTER] JOIN syntax in the FROM clause, or apply the outer join operator (+) to all columns of B in the join condition in the WHERE clause. The CASE expression goes through conditions and returns a value when the first condition is met (like an if-then-else statement). I'm here looking for more performant alternatives :) – Mar 27, 2012 · Im trying to avoid unioning multiple select statements by utilizing a CASE inside a WHERE clause. If you want to use the CASE statement in the WHERE clause, you’ll need to copy and paste the same CASE statement, instead of use the “continent” name. rate, c. column2,a. type IN (1, 3) AND a. Case your column and your string identically. * from . If you got yourself down to a single sharable SQL statement, then in addition to avoiding the cost of constantly re-parsing the statement, you'd have a number of options for forcing a particular plan that don't involve modifying the SQL statement. 0. customer_id = pcustomer_id. 2. So, when possible, rewrite lengthy IF-THEN-ELSIF statements as CASE statements. I've never had the need to use a CASE statement in a WHERE clause in this way before Oct 13, 2010 · Hello gurus, Can we use case statements in where clause ?? Any example will be great! And also i would like to know, besides CASE and DECODE statements, Is there any way we can use IF ELSE statemen Jan 5, 2021 · Never use commas in the FROM clause. Also, something needs to be done about the terribly long landing_page. end; In where clause i want Jan 17, 2020 · Hello Tom Is it possible to change the where condition (using case statement) based on certain variable? For example var T varchar2(1) exec :T := 'E'; var E number; exec :E := 7788; var N varchar2(20) exec :N := 'MILLER'; select empno, ename from emp where -- how to use case statement to vary the condition based on :T -- if :T = 'E' then the condition should be where empno = :E -- and if :T Jul 14, 2009 · I do not think this is generally the case, as it would prevent an index from being used. 7 WHEN 'C+' THEN 2. But when it comes to query (in select statement) will using nvl make it slower? I have a package that have loads of select statement with NVl. Below is how you would write a statement to avoid using Mar 27, 2012 · Im trying to avoid unioning multiple select statements by utilizing a CASE inside a WHERE clause. And don’t forget to take the quiz . Jan 4, 2012 · I posted the following question yesterday: Multiple 'in' statements in a where clause that need to match against each other In this there was some discussion about a feature in Oracle which doesn't exist in Microsoft SQL, the specific line of code being: Jul 7, 2017 · And this is where the WITH clause comes in. We can (and in fact do) change the order of evaluation whenever we feel like it. 7 WHEN 'B+' THEN 3. Just use AND, OR, and the appropriate parentheses. Example: Select Acc , Case when Calculation_type = 'M' then Min_value when Calculation_type = 'E' then Ending_value Else Average_BLC END From Table alternative Dec 14, 2020 · Using DECODE() function containing CASE. I'm not really sure how to write this. Example: Count of employees in each performance category Oct 17, 2024 · The PL/SQL CASE statement is a powerful conditional control structure in Oracle databases that allows you to execute different blocks of code based on specified conditions. case in where clause - Toad SQL. SELECT ID, NAME, (SELECT (Case when Contains(Des Is there any difference (performance, best-practice, etc) between putting a condition in the JOIN clause vs. Aug 7, 2018 · CASE <expression> WHEN <comparison expression> THEN <return expression> … or. If the @UserRole variable value = 'Analyst', then the SupervisorApprovedBy column value must be NULL. Create Procedure( aSRCHLOGI May 25, 2009 · I need help in a query using case statements in where clause. partition_id THEN 1 ELSE 0 END = 1 May 3, 2016 · The CASE Statement. Jul 7, 2024 · In contrast, the CASE WHEN statement is used across multiple SQL dialects, including PostgreSQL, MySQL, Oracle, and SQL Server, in SELECT, UPDATE, and DELETE statements to handle multiple conditions. with tmp as ( select 'Oracle' as field_name , 1 as data from dual union all select 'Oracle' as field_name , null as data from dual union all select NULL as field_name , null as data from dual union all select 'Test' as field_name , null as data from dual ) Select * from tmp Where 1 = case when field_name = 'Oracle' and data is null then 0 else 1 end Jun 8, 2015 · You can use a case: SELECT (columns list) FROM AGREEMENT A WHERE A. COL1 FROM A1,C1 WHERE A1. column3 from Table a, (Select distinct b. Aug 1, 2017 · I have a WHERE clause that I want to use a CASE expression in. SELECT empno, ename, job FROM scott. "The CASE expression cannot be used to control the flow of execution of Transact-SQL statements, statement blocks, user-defined functions, and stored procedures. How can I do it? Jul 4, 2009 · Query A says start with managers in the Sales department and then get all their employees. Ultimately what method you choose is dependent on your individual circumstances; the main thing to remember is that to improve performance you must index correctly for case-insensitive searching. May 5, 2015 · The case statement is an expression that returns a single value. select one, two, three from orders where orders. The difference here is that SQL is a declarative language. NEXT_DATE = V_NEXT_BUSINESS_DATE OR F. . You can either put your query in a subselect: SELECT gpaScore FROM (SELECT ( CASE grade WHEN 'A+' THEN 4 WHEN 'A' THEN 4 WHEN 'A-' THEN 3. field = @var or @var = 0 Jun 26, 2023 · This SQL tutorial will guide you on conditionally filtering using the WHERE clause using a SQL CASE statement. However, as not all the input fields are mandatory from the front end, I have to use CASE statement in WHERE clause. CustomerID Jan 3, 2014 · Oracle doesn't treat Boolean expressions like other expressions — it handles them as syntax rather than as a type — so CASE expressions can't evaluate to Booleans. Same execution time. Jul 12, 2012 · But it should alleviate the slowness in this case. column2 from tableb) b where (Case when b. ID_DOC = D. Unfortunately, I still need to use this in Oracle. Here are some solutions to help you navigate these challenges: 1. May 15, 2014 · For appeals, questions and feedback about Oracle Forums, please email oracle-forums-moderators_us@oracle. "1", however doing so does not accomplish my goal. Precisely, with CASE statement in WHERE clause, Oracle is not using index. the WHERE clause? For example-- Condition in JOIN SELECT * FROM dbo. What is Oracle Case Statement? Oracle Case Statement is similar to the IF-THEN-ELSE statement in PL/SQL but with the advantage of using it inside SQL without calling a procedure. Another way to use the Case Statement is within the WHERE clause. roleid AND rolename IN ( CASE WHEN (1 < 2) THEN ('Owner Role') WHEN (2 < 1) THEN ('Eval Owner Role') END); You can also write this without the case statement. Thank you! Interested in getting your voice heard by members of the Developer Marketing team at Oracle? Check out this post for AppDev or this post for AI focus group Mar 24, 2015 · Both the statements will be having same performance as SQL Server is smart enough to parse both the same statements into a similar plan. To avoid such performance problem as multiple CASE statement in SQL, we need to rewrite the query. D_OrganizationID > 2 THEN OrganizationDesc. 8 9 2) Case: 10 11 a) If the <search condition> of some <searched when clause> in 12 a <case specification> is true, then the value of the <case 13 It is NOT ALWAYS TRUE that there is no difference between join and where clause. I would continue to work with your vendor on indexing strategies if possible. column2 is not null then a. Introduction to SQL CASE Statement. When working with SQL CASE statements, there are a few common pitfalls you might encounter. But in Exadata , Decode is faster than CASE. Jun 23, 2020 · A short time ago we were introduced the incredibly useful and versatile Case Statement. The Feb 26, 2016 · The problem is that Oracle evaluates the SELECT after the WHERE clause. column2) Thanks for your help Mastering SQL CASE WHEN statements is critical for anyone working with relational databases, whether using SQL Server, MySQL, PostgreSQL, or another database management system. You are missing smth - see IN after END Replace 'IN' with '=' sign for a single value. (For user-defined functions, see below). Thank you! Interested in getting your voice heard by members of the Developer Marketing team at Oracle? Check out this post for AppDev or this post for AI focus group Aug 20, 2008 · I had played around with using the CASE statement in the where clause to sql more dynamic but had also run into the same problem with needing multiple values returned for the in. Oracle with CASE Statement Jul 14, 2018 · Following oracle query complies and works fine: SELECT Employee. col1 then select from A1 and B1 and if not select from A1 and C1 Thanks Dec 2, 2011 · Depending on your use case, instead of using a case statement, you can use the union of multiple select statements, one for each condition. My goal when I found this question was to select multiple columns conditionally. WHERE ( :APP_USER = 'xxx. Borrowing your example var l varchar2(4); exec :l := '551F'; with rws as ( select '551C' assembly_line from dual union all select '551S' assembly_line from dual union all select '551F' assembly_line from dual union all select '1234' assembly_line from dual ) select * from rws where case when :l Apr 7, 2016 · WHERE clause in query - does order really matter? Dear Tom,Yesterday we had a discussion at lunch regarding the performance impact of how the WHERE clause is constructed. CASE in WHERE statement. xxx' AND tmp. I've read that when using a CASE statement within a WHERE clause you have to surround the statement with parenthesis and assign it to a numeric value, e. COL1 FROM A1, B1 WHERE A1. Different versions of Oracle have different options for plan stability-- there are stored outlines Aug 20, 2019 · The option type = '1' is common in both cases so you can leave it out of the CASE statement (also because it would be syntactically wrong to try to return 2 values from the CASE statement): where type = '1' and status = case when carName = :P_PARAMETER then 'N' else 'Y' end Apr 29, 2024 · 1 1) Case: 2 3 a) If a <result> specifies NULL, then its value is the null 4 value. AreaSubscription WHERE AreaSubscription. Aug 4, 2020 · I am new to PL/SQL and trying to write conditional statement in join condition like below. In the absence of ordered_predicates, Oracle uses the following steps to evaluate the order of SQL predicates: Jul 5, 2021 · In PL-SQL using nvl will be easier that is true. As a WHERE clause already is a boolean expression, you don't need CASE expressions there, anyway. See this FAQ for details. if :P21_TYPEID value is 1 then in where clause it should be PARENTID_1 in (10,11) otherwise PARENTID_1 = :P21_TYPEID. Aug 7, 2013 · Try this. ) Else (Select ProductID from Product) End as ProductID ) FROM T1, T2 WHERE CASE T2. EmployeeId, Employee. Theoretically, the optimizer can take the version without the case and apply an optimization that transforms the subquery in your filter into a join; when the case statement is added this optimization is no longer possible and the subquery is executed for every row. Based on your first procedure example and the time difference between the C#-generated version and the proc, I'm guessing the WHERE clause in the proc version is killing any chance of optimization - probably the C# version has a much more targeted WHERE clause. CASE allows you to perform IF-THEN-ELSE logic in your SQL statements, similar to DECODE. I have multiple case statements running on the same column. customer_id IS NULL; and when pcustomer_id IS NOT NULL then c. STATUS, Oct 2, 2018 · (1) you can't use a case statement anywhere in a sql query; (2) you can use a case expression anywhere in a sql query where an expression is allowed, including the select and where clauses. I do the same for the business_unit column with a second CASE statement. If it was that simple and straightforward, life would be all rainbows and unicorns. UserID, U. CustomerID = ORD. CASE WHEN <condition> THEN <return expression> your query is malformed. These statements allow you to apply conditional logic directly within your SQL queries, enabling powerful data transformations and insights. In fact there is no such thing as a case statement in SQL Server, it is a case expression. orderid END Apr 2, 2020 · Case construct with WHERE clause Hi Tom, I have a question and I don't know if this is possible or if i'm jsut doing something wrong because i get multiple errors like missing right paren, or missing keyword. Tried a whole host of methods using STRAGG and in-list functions but kept running into limitations Thanks for showing how I can do dynamic where clauses without using pl/sql. SOME_TYPE LIKE 'NOTHING%') OR (T2. The case logic can be used within an INDEXCOL function, enabling Oracle Analytics to simplify the execution of the case Dec 2, 2020 · In the case of using Dynamic SQL there are times when a CASE Statement MUST be used due to the fact that there could be data that is being compared against in the WHERE clause that is NOT a column. Roughly, by using multiple WITH blocks (CTE's) I declare queries (I like to think them as ad-hoc views) to declare two distinct target set for both document types. BusinessId = CompanyMaster. FirstName = 'John' -- Condition in WHERE SELECT * FROM dbo. Like procedure samp (pId number, pValue varchar, details out T_cursor) is begin Open details for Select id, No,Name from tbl1 where. employee Aug 23, 2024 · 12. There, it may be utilized to alter the data fetched by a query based on a condition. DEPARTMENT, U. ID_DOC withount joining the JOBS table. All too often, I see the distinct clause used as a Band Aid for poor data structures, at the cost of [dire] performance. Currently doing a massive IN (1,2,. CompanyMaster WHERE AreaId IN (@AreaId) END ELSE BEGIN Jul 19, 2011 · It is a perfect scenario for using CASE statement in WHERE clause, and here is the complete query in Oracle PL/SQL: SELECT U. How to Avoid Multiple Evaluations of a Subquery in a Simple CASE Expression. But, ideally you should use WHERE clause syntactically. Jan 12, 2015 · Complex Case Statement in Oracle SQL. Feb 6, 2012 · Oracle SQL Case Statement in Where Clause. select a. Getting an actual filtering mechanism in place, performance shoots through the roof. However, dynamic SQL seems like overkill in this case. SOME_TYPE NOT LIKE 'NOTHING%') Share Apr 7, 2016 · Yesterday we had a discussion at lunch regarding the performance impact of how the WHERE clause is constructed. Customers AS CUS INNER JOIN dbo. You could use it thusly: SELECT * FROM sys. I could of course write an IF block with 7 ELSE statements essentially writing the same select statement 7 times, but I'm guessing the above can't be too far off. date, b. In addition: Don't use commas in the from clause. Therefore, no need for the over-complicated UNION hack (which incidently gives the same cost as the CASE). BETWEEN is unnecessary assuming that datet is not in the future. (This does not affect performance, however. Always use proper, explicit join syntax. The SQL CASE statement specifies a conditional expression to perform different actions depending on the input expression value. Dec 4, 2013 · For appeals, questions and feedback about Oracle Forums, please email oracle-forums-moderators_us@oracle. Mar 5, 2023 · Guffa has the right answer, but the way you'd do this using the CASE trick (which does occasionally come in handy) is this:--If order ID is greater than 0, use it for selection --otherwise return all of the orders. GRP_ID ELSE ? END And Decode works in a similar fashion, although I think it's less readable. Sep 12, 2005 · How and when a "CASE" is executed with in a statement? currently when using a CASE i have serious performance issues even though the consistent gets are low? Thanks, March 18, 2003 - 4:43 pm UTC Feb 21, 2019 · I’m commonly asked whether whether I can have a CASE Statement in the WHERE Clause. col1 matches B1. Feb 9, 2024 · A CASE expression returns a scalar value and not an expression (or list of expressions). If no conditions are true, it returns the value in the ELSE clause. If you want to use case, then you need to return a value and do a comparison: (CASE order_date > sysdate and fee_rate_type in ('REGULAR', 'BONUS') then 1 order_date <= sysdate and FEE_RATE_TYPE in ('REGULAR') then 1 END) = 1 Sep 29, 2010 · I want to use Case statement in where clause for Example Select a. While the CASE statement works in a way that is similar to a WHERE clause, it’s not a WHERE clause and therefore, scans. indexes i JOIN sys. column1 = b. Table1. If country is USA, then I want emp_id to Jun 18, 2013 · As for your question "does the entire statement need to be dynamic sql", the answer is yes. COL1, C1. alter session set NLS_COMP=ANSI; alter session set NLS_SORT=BINARY_CI; Oct 15, 2012 · 2- is better to to Write 2 or more Queries each handling one option of the Case when value rather than writing a one Single Query having a case when statement. Jul 2, 2014 · @ErwinSmout - I can't believe I never followed up on your comment. type IN (2) AND a. So, once a condition is true, it will stop reading and return the result. aid c inner join b. select col1,col2, case when col3='E01089001' then 1 else 2 end, case when col3='E01089001' then 3 else 4 end end from Table1, dual where col1='A0529'; Apr 12, 2023 · You can define case statements in the column formula of reports or in the Oracle Analytics repository (RPD) file. Nov 19, 2011 · There's a more fundamental question that's not being asked here: What are these CASE statements actually doing?. ColumnName FROM Schema. I want to use the CASE construct after a WHERE clause to build an expression. I optimize the long running queries all the time and sometimes the queries using where clause perform better than those using join by a factor of up to 70x. ) decode() is rather hard to follow. 13. Try writing the where clause this way: WHERE (T2. But having erratic performance. The syntax for the CASE statement in a SQL database is: Oct 20, 2016 · It is not an assignment but a relational operator. – Jeffrey Kemp Sep 3, 2018 · An even better solution is to add to a Summary Table every month. Thank you! Interested in getting your voice heard by members of the Developer Marketing team at Oracle? Check out this post for AppDev or this post for AI focus group Aug 4, 2020 · I am new to PL/SQL and trying to write conditional statement in join condition like below. id = b. I hope this would be allowed in Oracle PL/SQL) select . DECLARE @AreaId INT = 2 DECLARE @Areas Table(AreaId int) INSERT INTO @Areas SELECT AreaId FROM AreaMaster WHERE CityZoneId IN (SELECT CityZoneId FROM AreaMaster WHERE AreaId = @AreaID) IF EXISTS (SELECT BusinessId FROM dbo. Always remember that distinct removes duplicates so May 16, 2017 · Here's another attempt without using a CASE STATEMENT but returns no result: SELECT e. Another win for the MSSQL case (no pun intended!!) Sep 30, 2016 · I'm interesting that how can I use if-then-else statement or any control structure in where clause in Oracle. type, a. Oracle doesn't "know" that all the employees returned be the query will be in the Sales department, so it can't use that information to reduce the set of data to work with before performing the CONNECT BY. You can safely move it into FROM clause; a sane query plan builder would do it automatically. column1 is not null then a. COL1 END FROM A1,B1,C1; That is if A1. Jul 11, 2016 · I look for a working example where I can use mutliple when case statment wihch check to verify if a specific text is contained: e. name = 'xxx' select * from #t where rate>0 Mar 9, 2011 · For appeals, questions and feedback about Oracle Forums, please email oracle-forums-moderators_us@oracle. Dec 7, 2023 · How to use CASE in the WHERE clause. I don't want to write a Dynamic SQL. In what scenarios would you prefer using a CASE WHEN statement over using a JOIN clause? Apr 21, 2012 · A CASE expression returns a value from the THEN portion of the clause. This modified query is doing a full table scan and running endlessly. If it's not used often at all, it might be ok. 2) Keep my CASE statement with your SELECT 1 FROM JOBS J WHERE J. When the parameter is defined as 'New Items' it should utilize one code and for 'Updated Items' another condition. The result of the case statement is either 1 or 0. The question was the following: Assuming a variable @var that is an integer and has a value of 0 (zero). SQL case query with multiple statement. 7 WHEN 'F' THEN 0 ELSE Oct 20, 2013 · The CASE statement is evaluated in order, so if any "case" is true then every case after it is ignored. 3 WHEN 'D' THEN 1 WHEN 'D-' THEN 0. Moreover, your query would have never returned rows with department - "Accounts or Unknown" because of the filter Department="SALES" As shown in the output, the statement returned the number of products for each product that appears in the order_items table. Which access is faster depend upon the selectivity of the inner query and the clustering of the index on TABLE1 (are the rows with similar value of col2 in TABLE1 next to each other or randomly spread?). Apr 22, 2019 · I can't tell for sure without seeing an execution plan but the branch in your filter is likely the cause of the performance problems. IsFrozen FROM employee, employeerole, roledef WHERE employee. Basically, the following code is what I want, but it's not the Oracle correct syntax. It's specified in terms of the overall logic and, so long as it still logically computes the result it's asked to, the evaluation order should not matter. WHEN expression in it for the case flag_a='B' might be an alternative way to get the desired results such as SELECT no, SUM(qty) AS qty FROM ppp WHERE DECODE(flag_a,'P',0,'C',1,'B', CASE WHEN flag_b IN (0,1) THEN flag_b END)=flag_b GROUP BY no Oct 24, 2018 · Your lead is wrong. We have yet to look at the performance of CASE versus another method. I was using Oracle 10gR2 above. Oct 20, 2016 · You can also go the other way and push both conditionals into the where part of the case statement. bid where a. CASE Jun 29, 2011 · Is it possible to use a SELECT statement within case For ex, SELECT CASE WHEN A1. Does anybody have any idea what the correct syntax should be like?. Jan 19, 2012 · Is it possible in Oracle to put conditional IF statements in the WHERE clause? I want to filter all rows with an end date before today. Mar 22, 2011 · There are 3 main ways to perform a case-insensitive search in Oracle without using full-text indexes. Nice work. Or you can slap the case expression directly in the where clause, like so: May 29, 2012 · The order of evaluation of the where clause in a SQL statment is purposely "undefined". AND (CASE E WHEN spriden_ntyp_code = 'CHSN' then spriden_ntyp_code = 'CHSN' WHEN spriden_ntyp_code <> 'CHSN' then spriden_change_ind IS NULL Feb 15, 2022 · i tried Case in With clause but still failed, please help. May 5, 2012 · In my WHERE Clause IS the AND F. Always use proper, explicit, standard, readable JOIN syntax. employeeid AND employeerole. field value but a hardcoded value that is compared to perhaps a user selection or status (as examples) it might be a static value passed in via Apr 30, 2014 · As I commented below the CASE statement does indeed get around the issue. Thank you! Interested in getting your voice heard by members of the Developer Marketing team at Oracle? Check out this post for AppDev or this post for AI focus group Oct 16, 2008 · The problem with this is that when the SQL engine goes to evaluate the expression, it checks the FROM portion to pull the proper tables, and then the WHERE portion to provide some base criteria, so it cannot properly evaluate a dynamic condition on which column to check against. COMPARE_TYPE WHEN 'A' THEN T1. Case statements defined on variables. " Reference Aug 19, 2010 · For appeals, questions and feedback about Oracle Forums, please email oracle-forums-moderators_us@oracle. SOME_TYPE LIKE 'NOTHING%' ELSE T1. Some databases do, but not Oracle. Hi all, Oct 18, 2009 · SELECT col1 as a, CASE WHEN a = 'test' THEN 'yes' END as value FROM table; I am trying to alias the column because actually my CASE statement would be generated programmatically, and I want the column that the case statement uses to be specified in the SQL instead of having to pass another parameter to the program. Sep 21, 2015 · I'm trying create report filters using substitution variables in case statement in a where clause. D_OrganizationID = 2 THEN 'Undefined Consumer'. COL1, B1. Create Procedure( aSRCHLOGI Oct 9, 2013 · I believe you can use a case statement in a where clause, here is how I do it: Select ProductID OrderNo, OrderType, OrderLineNo From Order_Detail Where ProductID in ( Select Case when (@Varibale1 != '') then (Select ProductID from Product P Where . Jan 14, 2016 · Oracle tries to filter the number of records to be scanned from table by going for the where clause first before select that is why your query fails. SOME_TYPE NOT LIKE 'NOTHING%' END I know that my WHERE is clause is not correct. Create Procedure( aSRCHLOGI This is working Oracle example but it should work in MySQL too. container_id = p. Not procedural. com. col1 then select from A1 and B1 and if not select from A1 and C1 Thanks Feb 11, 2011 · In that case Oracle will read the rows from TABLE2 and for each (unique) row, perform an index access on TABLE1. In almost all databases, it comes down to "the optimizer understands boolean expressions". Also, calling EXPLAIN PLAN on any query you're going to use in production is a must. compute_zone = case when :P14_zone is NOT NULL Mar 31, 2020 · I never use case statements is a where clause, I have this case statement. Both perform good. The question was the following:Assuming a variable @var that is an integer and has a value of 0 (zero). field = @var b) SELECT () WHERE table. Apr 14, 2008 · Oracle has updated its online CASE statement in where clause. I tried to put it in case statement but it didn't work. In any case, performance wise Mar 14, 2013 · The CASE statement evaluates multiple conditions to produce a single value. Nested CASE statements in SQL. Then filter it in the outer query. employeeid = employeerole. emp WHERE (CASE WHEN job = 'MANAGER' THEN '1' WHEN job = 'CLERK' THEN '2' ELSE '0' END) IN (1, 2) Aug 13, 2021 · This tutorial will explain how to use Oracle Case Statement expression with basic syntax and many examples for better understanding. status. COL1=B1. 1) LEFT JOIN the JOBS table and then use your CASE statement. The problem with the case (as you have written it) is that Oracle does not treat the value from a logical expression as a valid value. column1,a. The optimizer looks at the predicate, analyzes the available access paths, chooses the appropriate indexes and executes the query. SQL/PLSQL Oracle query: CASE in WHERE statement. However, how can we accomplish the same results differently by not using a CASE expression? The one I see recommended the most is using a UNION ALL operator. 3 WHEN 'C' THEN 2 WHEN 'C-' THEN 1. Thank you! Interested in getting your voice heard by members of the Developer Marketing team at Oracle? Check out this post for AppDev or this post for AI focus group Aug 30, 2021 · I am trying to write a "case" statement inside a "where clause" which has an "in" statement in the "then" part. Apr 6, 2021 · We also saw 4 CASE WHEN expressions in the Compute Scalar operator. In your case, I think the clearest code is if you just rewrite it a bit: Jun 23, 2009 · Use ALTER SESSION statements to set comparison to case-insensitive: alter session set NLS_COMP=LINGUISTIC; alter session set NLS_SORT=BINARY_CI; If you're still using version 10gR2, use the below statements. column1,b. So, in the first usage, I check the value of status_flag, returning 'A', 'T' or null depending on what it's value is, and compare that to t. Jul 7, 2010 · From performance perspective, In Oracle decode and CASE does not make any difference. If CASE is only being used to transform the final output of a query, and it's actually possible to replace the same functionality with an if or select case in ASP, then it probably means that the database query/procedure is trying to do things that Nov 2, 2023 · Here, the SQL CASE statement checks for NULL values in PerformanceRating and marks them as 'Pending Evaluation'. select * from Users where Regexp_Like (User_Name, 'karl|anders|leif','i') This will be executed as a full table scan - just as the LIKE or solution, so the performance will be really bad if the table is not small. So it’s about applying a mechanism that lets SQL Server filter as opposed to a straight scan. However, you can achive this in your WHERE clause without using a CASE statement: WHERE (desc1 = 'desc1' AND status_code IN (240,242)) OR (desc1 = 'desc2' AND status_code IN (240,245)) Feb 12, 2014 · Is it possible to use between operator within a CASE statement within a WHERE Clause ? For example in the code below, the condition should be pydate between (sysdate-12) and (sysdate-2) if its a mo Sep 17, 2021 · I have a select statement like below select * from employees where emp_id <= v_emp_id; I want this emp_id to be <= v_emp_id if country is not USA. On the other hand, what makes a difference is data type used in the boolean expression. roleid = roledef. NEXT_DATE IS NULL; can be written in another way I mean since It is using both AND and OR Operators on the same column . NAME, D. 1. COMPARE_TYPE <> 'A' AND T1. lbfhws klbrpt pjapy svwtcn xmmlf mlex poja ujt usyuutc gcofi