Create a CHECK Constraint in MySQL

As of MySQL 8.0.16, we can create CHECK constraints in MySQL.

A CHECK constraint is a type of integrity constraint. It specifies a search condition to check the value being entered into a row. If the value being entered violates the CHECK constraint, then the result of the search condition is FALSE and an error occurs (unless the IGNORE clause is used in the SQL statement, in which case a warning is reported and the offending row is skipped).

The ability to create CHECK constraints was introduced in MySQL 8.0.16. Prior to version 8.0.16, MySQL actually allowed a limited version of CHECK constraint syntax, but it was completely ignored (no CHECK constraint was created or evaluated).

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Understanding the sys.ps_is_thread_instrumented() Function in MySQL

In MySQL, we can use the sys.ps_is_thread_instrumented() function to check whether Performance Schema instrumentation for a given connection ID is enabled.

The function returns YES or NO, depending on whether the instrumentation is enabled for the given connection. It can also return UNKNOWN if the connection ID is unknown, and NULL if the connection ID is NULL.

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