How to write mysql check constraints

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MySQL method for writing check constraints: 1. Use the ENUM data type. The ENUM data type allows us to define a fixed list of values ​​when creating a table, and then limit the value of the column to a value in the list. For example, you can create a named is the gender column, and defines it as ENUM('male', 'female'), so that the value of this column can only be 'male' or 'female'; 2. Use a trigger. The trigger is a specific A database object that executes automatically when an event occurs. Triggers can be used to implement more complex check constraints.