MySQL Update or insert

INSERT ... On DUPLICATE KEY UPDATE statement

MySQL has been supporting insert since version 4.1 ... On DUPLICATE KEY UPDATE syntax, it is necessary to execute 3 SQL statements (select,insert,update), reduced to 1 statements to complete.

INSERT ... On DUPLICATE key Update, when an inserted record raises a primary key conflict or violates a unique constraint, the old record is updated with update, otherwise a new record is inserted.

Note that to use this statement, the condition is that the table must have a unique index or primary key.

This statement is not recommended in cases where there are multiple unique indexes (or if there are keys and unique indexes).

MySQL Update or insert