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1 lut 2010 · Here's a query to update a table based on a comparison of another table. If record is not found in tableB, it will update the "active" value to "n". If it's found, will set the value to NULL. UPDATE tableA LEFT JOIN tableB ON tableA.id = tableB.id SET active = IF(tableB.id IS NULL, 'n', NULL)"; Hope this helps someone else.
In this article, we would like to show you UPDATE query with IF condition in MySQL. Quick solution: UPDATE `table_name` SET `column_name` = IF(condition , if_true, if_false); Practical example. To show UPDATE query with IF condition, we will use the following users table:
The WHERE clause, if given, specifies the conditions that identify which rows to update. With no WHERE clause, all rows are updated. If the ORDER BY clause is specified, the rows are updated in the order that is specified. The LIMIT clause places a limit on the number of rows that can be updated.
16 kwi 2016 · However, given how the conditions are re-used in your UPDATE statement, you could also take a different approach altogether: represent the affected IDs and the new values as a derived table and use an update with a join:
Notice the WHERE clause in the UPDATE statement. The WHERE clause specifies which record(s) that should be updated. If you omit the WHERE clause, all records in the table will be updated!
11 mar 2015 · IF EXISTS (SELECT id FROM user_roles WHERE user_id = 5 AND end_date IS NULL) THEN UPDATE user p JOIN user_roles ur ON p.id = ur.user_id SET ur.end_date = NOW() , p.end_date = NOW() , p.reason = "Retired" WHERE p.id = 5 AND ur.end_date IS NULL ELSE UPDATE user SET end_date = NOW() , reason = "Retired" WHERE id = 5 END IF
Summary. Use IF...THEN statement to conditionally execute a block of statements based on the evaluation of a specified condition. Use IF...THEN...ELSE statement to execute a block of statements if a specified condition is true and an alternative block of statements if the condition is false.
