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28 Απρ 2019 · I'm trying to create a CASE STATEMENT in SQL (Oracle) where I need to select only single rows in addition to other criteria. I'm trying to do it this way: A.*. ,D.*. ,(CASE WHEN (A.COLUMN1 = D.COLUMN2) AND (D.COLUMN3 = 1) AND (DISTINCT A.COLUMN4) THEN 1. ELSE 0.
Oracle CASE expression allows you to add if-else logic to SQL statements without having to call a procedure. The CASE expression evaluates a list of conditions and returns one of the multiple possible results. You can use a CASE expression in any statement or clause that accepts a valid expression.
The syntax for the CASE statement in Oracle/PLSQL is: CASE [ expression ] WHEN condition_1 THEN result_1 WHEN condition_2 THEN result_2 ... WHEN condition_n THEN result_n ELSE result END Parameters or Arguments expression Optional. It is the value that you are comparing to the list of conditions.
In a simple CASE expression, Oracle Database searches for the first WHEN... THEN pair for which expr is equal to comparison_expr and returns return_expr. If none of the WHEN... THEN pairs meet this condition, and an ELSE clause exists, then Oracle returns else_expr. Otherwise, Oracle returns null.
The CASE function specifies conditions and results for a select or update statement. You can use the CASE function to search for data based on specific conditions or to update values based on a condition. Example. SELECT CASE JOB WHEN 'PRESIDENT' THEN 'The Honorable' WHEN 'MANAGER' THEN 'The Esteemed' ELSE 'The good' END, ENAME FROM EMP;
Is there a "better" way to rewrite a SELECT clause where multiple columns use the same CASE WHEN conditions so that the conditions are only checked once? See the example below.
22 Μαΐ 2013 · Can you please settle an argument we are having re: "select unique" vs. "select distinct"? The Oracle docs say they are synonymous, but it seems to imply that "distinct" forces a sort where "unique" does not. In that case they aren't synonymous and "unique" would be wrong if the input weren't already sorted by a subquery wouldn't it?
