Can MySQL Update Multiple Rows in a Single Query?

MySQL batch row update

MySQL's INSERT statement allows multiple rows of data to be inserted simultaneously. But, can I update multiple rows with a single query?

Batch update query

Yes, you can use the INSERT ... ON DUPLICATE KEY UPDATE statement to update multiple rows at once. When a row is inserted into a table and a primary or unique key already exists, the following happens:

• If the INSERT statement contains a DUPLICATE KEY UPDATE clause, then the existing row is updated using the value provided in the update clause.
• If the INSERT statement does not contain a DUPLICATE KEY UPDATE clause, an error is generated.

Example

Consider the following form:

Name	id	Col1	Col2
Row1	1	6	1
Row2	2	2	3
Row3	3	9	5
Row4	4	16	8

We would like to combine the following updates into a single query:

<code class="language-sql">UPDATE table SET Col1 = 1 WHERE id = 1;
UPDATE table SET Col1 = 2 WHERE id = 2;
UPDATE table SET Col2 = 3 WHERE id = 3;
UPDATE table SET Col1 = 10 WHERE id = 4;
UPDATE table SET Col2 = 12 WHERE id = 4;</code>

The corresponding batch update query using INSERT ... ON DUPLICATE KEY UPDATE is as follows:

<code class="language-sql">INSERT INTO table (id,Col1,Col2) VALUES (1,1,1),(2,2,3),(3,9,3),(4,10,12)
ON DUPLICATE KEY UPDATE Col1=VALUES(Col1),Col2=VALUES(Col2);</code>

This query inserts a new row if it does not already exist, or updates an existing row if the primary key already exists in the table.

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