MySQL table data does not exist then insert, otherwise update data

There are times when we manipulate database tables, but when we insert data into a table, we encounter data that already exists in the table for that ID or data without that ID, insert it directly when there is no data for that ID, and then update the data for that ID if you encounter data that already exists for that ID.

Here we use the REPLACE into statement, which is an enhanced version of the INSERT INTO statement that can do this, but only if the data in the table has a primary key that is unique, or replace into is treated as an INSERT INTO statement, inserting duplicate data.

For example:

REPLACE into TestUser (id,letters) VALUES (2, ' dfsdf ')

The effect is as follows:

　　

MySQL table data does not exist then insert, otherwise update data