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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.
18 lut 2018 · It is possible to update rows based on some condition. It is also possible to update multiple tables in one statement in MySQL. Whether the latter is a good idea is debatable, though.
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:
If a subquery returns any rows at all, EXISTS. subquery is TRUE, and NOT EXISTS. subquery is FALSE. For example: SELECT column1 FROM t1 WHERE EXISTS (SELECT * FROM t2); Traditionally, an EXISTS subquery starts with SELECT *, but it could begin with SELECT 5 or SELECT column1 or anything at all.
27 sty 2024 · It works by attempting to insert a new row. If the insertion would result in a duplicate entry for a PRIMARY KEY or a UNIQUE index, MySQL updates the existing row instead. INSERT INTO table_name (column1, column2, ...) VALUES (value1, value2, ...) ON DUPLICATE KEY UPDATE column1 = value1, column2 = value2, ...;
5 lut 2011 · How would one go about performing two UPDATE statements in one query, for example: UPDATE albums SET isFeatured = '0' WHERE isFeatured = '1'. combined with. UPDATE albums SET isFeatured = '1' WHERE id = '$id'.
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!
