How does the case statement work in SQL?

The SQL CASE Statement The CASE statement goes through conditions and returns a value when the first condition is met (like an if-then-else statement). So, once a condition is true, it will stop reading and return the result. If no conditions are true, it returns the value in the ELSE clause.

How is a case expression evaluated in Transact SQL?

For a list of control-of-flow methods, see Control-of-Flow Language (Transact-SQL). The CASE expression evaluates its conditions sequentially and stops with the first condition whose condition is satisfied. In some situations, an expression is evaluated before a CASE expression receives the results of the expression as its input.

Can you have more than one condition in a case statement?

We can have multiple conditions in a Case statement; however, it works in a sequential model. If one condition is satisfied, it stops checking further conditions The Case statement in SQL provides flexibility in writing t-SQL for DDL and DML queries. It also adds versatility to SQL Server queries.

When do you use the case keyword in SQL?

Case keyword is followed by the WHEN statement, and there is no expression between CASE and WHEN. E.g.: CASE WHEN THEN Statement_1…. In Simple Case, VALUE exists for each WHEN statement.

What happens if the datatype is not the same in the case statement?

The CASE statement returns any datatype such as a string, numeric, date, etc. (BUT all results must be the same datatype in the CASE statement.) If all conditions are not the same datatype, an ORA-00932 error will be returned. If all results are not the same datatype, an ORA-00932 error will be returned.

How to switch case in where clause in SQL?

SQL keeps complaining about my ‘=’ on the first WHEN line… How can I do this? without a case statement… Here you go.

How are SQL CASE expressions evaluated in Stack Overflow?

The expressions are evaluated from left to right, and the value associated with the first expression to evaluate to True is returned. If the parts aren’t properly paired, a run-time error occurs. For example, if expr-1 is True, Switch returns value-1. If expr-1 is False, but expr-2 is True, Switch returns value-2, and so on.