How does the case statement work in SQL?
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. If there is no ELSE part and no conditions are true, it returns NULL.
When did PL / SQL start supporting case statements?
They have been part of the SQL standard since 1992, although Oracle SQL didn’t support CASE until the release of Oracle8 i Database, and PL/SQL didn’t support CASE until Oracle9 i Database Release 1. From this release onwards, the following types of CASE statements are supported:
When to use end case clause in PL / SQL?
The END CASE clause is used to terminate the CASE statement. The following example demonstrates the PL/SQL CASE statement. We’ll use the employees table in HR sample data provided by Oracle for the demonstration.
How is a case statement used in a cross tab query?
Sum (Case….End) or Count (Case…End) are informally known as Cross Tab queries, they are used to display data by column as opposed to as in row. Your Version of the Case Statement would return one or zero every time, where as the OP (I do believe) wants to return the sum of the values that meet the criteria of the Case.
When to use searched CASE expression in SQL?
If you want to use other comparison operators such as greater than (>), less than (<), etc., you use the searched CASE expression. The CASE statement returns the result_1, result_2, or result_3 if the expression matches the corresponding expression in the WHEN clause.
When to use Boolean expression in case statement in SQL?
If the Boolean expression in each WHEN clause evaluates to true, the searched CASE statement returns the result in the corresponding THEN clause. If no Boolean expression returns true, the CASE expression return the result else_result in the ELSE clause. Like the simple CASE expression, the END clause is optional.
What do you do with an email address in SQL?
And if it is, you can break an address into its component parts—before and after the “@” symbol—to classify users as consumers (e.g., gmail.com) or business users (e.g., microsoft.com). The functions below show how to do these operations directly in SQL.