How Can SQL CASE Statements Handle Conditional Logic in SELECT Queries?

Case Statements in SQL SELECT Queries

Consider this scenario: you need to select specific columns and apply conditional logic to retrieve different results based on certain criteria. In SQL, you can use a CASE statement to handle such scenarios.

A CASE statement allows you to define different conditions and assign corresponding results to each condition. Here's an example that matches the provided criteria:

SELECT xxx, yyy,
CASE
  WHEN bbb THEN 'blackberry'
  WHEN sss THEN 'samsung'
  ELSE NULL  -- Handle cases where neither condition is met
END AS handphone
FROM (
  ...  -- Your original SELECT statement here
) AS subquery;

In this query, you're retrieving the columns xxx, yyy, and a new column named handphone. The CASE statement checks for conditions bbb and sss. If either of those conditions is met, it returns the corresponding result, 'blackberry' or 'samsung'. Otherwise, it returns NULL.

This query will generate a table with the desired columns and conditional results, as shown in the provided example:

name	age	handphone
xxx1	yyy1	blackberry
xxx2	yyy2	blackberry

Keep in mind that the syntax and usage of CASE statements can vary depending on the specific database system you're using. It's recommended to consult the documentation of your database for detailed implementation guidelines.

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