(vi) MySQL: Learn SQL syntax (check constraints) on W3Schools documents

A CHECK

1.

Check constraints are used to limit the range of data that is filled in

When a check is used on a column in a table, it restricts only the data for that column

When check is used for a table

2. Syntax: MySQL

1. Use check (constraints) directly when creating a table

2. Add a check to a table you've created

2.1 Single condition

　　

More than 2.2 conditions

　　

3. Discard CHECK constraints

(vi) MySQL: Learn SQL syntax (check constraints) on W3Schools documents