How to Use MySQL's UPDATE Query with LIMIT Clause?

MySQL UPDATE Query with Limit: Syntax and Usage

Updating a specified number of rows in a MySQL table can be done using the LIMIT clause in the UPDATE query. However, the syntax you provided:

UPDATE `oltp_db`.`users` SET p_id = 3 LIMIT 1001, 1000

is incorrect. The correct syntax for using LIMIT in an UPDATE query is:

UPDATE table_name
SET column_name = new_value
WHERE condition
LIMIT number_of_rows

In your case, to update the first 1000 rows starting from row 1001, you can use the following query:

UPDATE `oltp_db`.`users` SET p_id = 3
WHERE id BETWEEN 1001 AND 2000
LIMIT 1000

Updating Null Values in MySQL

If the rows you want to update have null values for the column you are updating, you can use the following query:

UPDATE `oltp_db`.`users` SET p_id = 3
WHERE p_id IS NULL

This query will update all rows with null values in the p_id column to the value 3.

Example Query

To illustrate these concepts, consider the following table users with a column p_id of data type INTEGER:

id	p_id
1000	NULL
1001	NULL
1002	NULL
1003	1

To update the first 500 rows with null values to 3, you can use the following query:

UPDATE `users` SET p_id = 3
WHERE p_id IS NULL
LIMIT 500

This query will update the first 500 rows with null values in the p_id column, leaving the remaining rows unaffected.

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