SQL Mastery: A Comprehensive Guide with 50 Scenarios for CASE WHEN

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CASE WHEN statements are a powerful tool for implementing conditional logic, allowing you to customize data processing based on various conditions.

I. Master CASE WHEN Statement:

Mastering the CASE WHEN statement involves understanding its syntax, practicing its application in different scenarios, and becoming proficient in using it to handle various conditional situations.

1. Understand the Syntax:

• Understand the structure, including the CASE, WHEN, THEN, ELSE, and END keywords.

SELECT
  column1,
  column2,
  ...
  CASE
    WHEN condition1 THEN result1
    WHEN condition2 THEN result2
    ...
    ELSE default_result
  END AS new_column_name
FROM
  your_table;

• CASE: Begins the CASE WHEN statement.
• WHEN condition1 THEN result1: Checks a condition, and if it is true, returns the specified result. You can have multiple WHEN conditions.
• ELSE default_result: If none of the conditions are true, returns the default result.
• END: Ends the CASE WHEN statement.
• AS new_column_name: Assigns a name to the column generated by the CASE WHEN statement.