Let's insert a new record that has been already existing in the table. If no matching data exists, the simple INSERT statement will be performed.If there's already a row, then it deletes matching data with the DELETE statement and uses a normal INSERT statement to insert a new row.It first tries to find out if there is any existing row in the table.On the other hand, if there is no row with the same key values, the new row is simply inserted into the table without any deletion.īy simply replacing the INSERT with REPLACE during the insertion of any row, MySQL will be performing the following operations: There are other methods to insert records into the MySQL table or update if they are already present. Essentially, if a row with identical key values already exists, it gets removed first, and the new row is inserted. INSERT record or UPDATE if they EXIST in MySQL. In MySQL, the REPLACE statement is utilized to insert a fresh row into a table or to update an existing row with the same primary key or unique index. Since there was already an id 1, so it was updated with a new name and age. The ON DUPLICATE KEY UPDATE clause will update the name and age if it finds a record with the same id. Alternatively, a new row will be inserted with the specified values if MySQL cannot find an already existing row with the same key.įor instance, in the above-created table students we'll try to insert a new row with an already existing id. If any row with the duplicate key exists, the specified columns will be updated with the new values. If you want to know if the value exists you should use a Select statement before the Insert. The ON DUPLICATE KEY UPDATE clause is added at the end of the INSERT statement. mysql> insert into t2 values (20000,'a','a',0) Query OK, 1 row affected (0.00 sec) mysql> insert into t2 values (20000,'a','a',0) ERROR 1062 (23000): Duplicate entry '20000' for key 'PRIMARY'. It is commonly used if you want to update certain columns of an existing row or insert a new row with default values if the row doesn't already exist. Explore techniques like INSERT IGNORE, REPLACE, and ON DUPLICATE KEY UPDATE. ![]() It works by updating a row in a table if it already exists, or inserting a new row if it doesn't exist already. Learn to insert rows in MySQL only if they dont exist. To apply MySQL INSERT if not exists, the ON DUPLICATE KEY UPDATE is also an alternative. Update (after clarification): For example, here is how to insert a row in t2 if a corresponding row do not already exist in t1: INSERT INTO t2 (v) SELECT temp.candidate FROM (SELECT 'test' AS candidate) temp LEFT JOIN t1 ON t1.v temp.candidate WHERE t1.v IS NULL. This statement changes the error that MySQL throws when you use a normal INSERT statement into a warning so that the execution of your query isn’t interrupted.Here, the insertion of the row with a duplicate key is ignored and the insertion of other rows will continue. You need to use some type of INSERT.SELECT query. The MySQL INSERT IGNORE statement is used to insert a new row and ignore execution errors causes by the statement. Let’s provide a sample query to execute REPLACE into John Doe. It is essentially like UPDATE but with INSERT capabilities. What REPLACE does is it overwrites existing records when found if it doesn’t exist yet, it will insert a new row. Without putting a constraint on the column that you want to be distinct, then MySQL will insert duplicate values just fine, and the following tutorials won’t work as intended. Use REPLACE to Insert if Not Exists in MySQL. Keep in mind that before you create an insert row if not exists query, the MySQL table in use must already have one or more column(s) with PRIMARY KEY or UNIQUE constraint. ![]() ![]() ![]() Using the ON DUPLICATE KEY UPDATE clause.There are three ways you can perform an “insert if not exists” query in MySQL:
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