Use of case when in SQL

Application scenario: In a table query, you will always encounter some fields of enumeration definitions, such as table: Last Name (Sex) field, 1 for male, and 2 for female. If you have too many enumerations to remember the meaning, you need to look at the table comments, which can be cumbersome and time-consuming. Here's how to compare the usage and benefits of case-when.

1. General Enquiry

SELECT name,sex from person;

Results:

2. When using case

SELECT name,case Sex when 1 then ' Male ' when 2 then ' women ' else ' other ' END from person;

Use of case when in SQL