Search results
26 cze 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.
8 mar 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.
For the single-table syntax, the UPDATE statement updates columns of existing rows in the named table with new values. The SET clause indicates which columns to modify and the values they should be given. Each value can be given as an expression, or the keyword DEFAULT to set a column explicitly to its default value.
SELECT * FROM t1. WHERE ROW(col1,col2) = (SELECT col3, col4 FROM t2 WHERE id = 10); For both queries, if the table t2 contains a single row with id = 10, the subquery returns a single row. If this row has col3 and col4 values equal to the col1 and col2 values of any rows in t1, the WHERE expression is TRUE and each query returns those t1 rows.
Put the distinct names in a separate table and then do an UPDATE JOIN: create table ProgramNames select distinct programName from Programs where programName regexp '^adobe.*cs[1-9]$' ; alter table ProgramNames add primary key (programName); update Programs A INNER JOIN ProgramNames B USING (programName) set A.category="Adobe Suites"; drop table ...
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.
4 sie 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.
