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8 Μαρ 2016 · The main issue is that the inner query cannot be related to your where clause on the outer update statement, because the where filter applies first to the table being updated before the inner subquery even executes. The typical way to handle a situation like this is a multi-table update.
26 Ιουν 2024 · Updating table rows using subqueries in MySQL enables precise modifications based on specific conditions or values from other tables. This technique leverages subqueries within the SET or WHERE clauses of the UPDATE statement, allowing dynamic and context-specific updates.
You cannot update a table and select directly from the same table in a subquery. You can work around this by using a multi-table update in which one of the tables is derived from the table that you actually wish to update, and referring to the derived table using an alias.
A MySQL subquery is a query nested within another query such as SELECT, INSERT, UPDATE or DELETE. Also, a subquery can be nested within another subquery. A MySQL subquery is called an inner query whereas the query that contains the subquery is called an outer query.
1 Νοε 2023 · To update a MySQL query based on a select query, you can use the UPDATE statement with a subquery. This allows you to update rows in one table based on the values returned from a select query on another table.
A subquery's outer statement can be any one of: SELECT, INSERT, UPDATE, DELETE, SET, or DO. For information about how the optimizer handles subqueries, see Section 10.2.2, “Optimizing Subqueries, Derived Tables, View References, and Common Table Expressions” .
4 Αυγ 2024 · Ever found yourself needing to update a bunch of rows in your database, but the condition for the update depends on data from another table? That’s where UPDATE with a subquery comes in handy. Let’s break it down.
