Search results
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 MySQL UPDATE Statement. The UPDATE statement is used to modify the existing records in a table. UPDATE Syntax. UPDATE table_name. SET column1 = value1, column2 = value2, ... WHERE condition; Note: Be careful when updating records in a table! Notice the . WHERE clause in the UPDATE statement.
For the multiple-table syntax, UPDATE updates rows in each table named in table_references that satisfy the conditions. Each matching row is updated once, even if it matches the conditions multiple times.
15 mar 2012 · UPDATE table SET A = 20 WHERE A > 20; UPDATE table SET A = 0 WHERE A <= 1; When A is NULL, it will not meet either of these conditions, and thus eliminates the need to specify that A not be NULL. Next, there's no need for the third condition as @Andre suggested. If A is between 1 and 20, it gets left as-is.
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:
29 kwi 2015 · IF EXISTS (select * from users where username = 'something') THEN. update users set id= 'some' where username = 'something'; ELSE. insert into users (username) values ('something'); END IF; end $$. delimiter ; and call it like this: call select_or_insert();
