Contents
What is the alternative for CASE statement in SQL?
Question: What is Alternative to CASE Statement in SQL Server? Answer: IIF Function.
Can you nest case statements in SQL?
CASE can be nested in another CASE as well as in another IF…ELSE statement. In addition to SELECT, CASE can be used with another SQL clause like UPDATE, ORDER BY.
How case is used in case in SQL?
SELECT COALESCE( CASE WHEN condition1 THEN calculation1 ELSE NULL END, CASE WHEN condition2 THEN calculation2 ELSE NULL END, etc… ) Wrap all those cases into one. I personally do it this way, keeping the embedded CASE expressions confined. I’d also put comments in to explain what is going on.
How to speed up processing time for case statement?
In general the advice for speeding up processing time for CASE statement (or DO SELECT statement or any other way of coding a series of tests) is to make sure that the most common cases are listed first, since once it finds a match it stops having to perform the other tests.
When to use multiple case statements in select?
If they are all different tables then this may be your best case scenario. UNLESS Table1.column1 values can be repeated (multiple rows=’1′, etc). In that case you may want to move from subqueries to joins.
Which is the best way to write a case expression?
One way to write this expression is: (In English working from the inside out: convert the result of the expression 1+RAND ()*5 to a smallint; if the result of that conversion is 3, set it to NULL; if the result of that is NULL, set it to -1. You could write this with a more verbose CASE expression, but concise seems to be king.)
How many unique values can a case expression return?
The key is that the CASE expression is only ever going to return 3 (or 30) unique values if it finds a match. You can save off the results into local variables and just use those in the query. The query below finishes in around 1.044 seconds: