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How to fix error code: 1242. Subquery returns more than 1 row?

Published on April 12th, 2022

Error code: 1242. Subquery returns more than 1 row.

This error code happens when a subquery returns more than one row. This can happen if the subquery is not well formed, or if the data in the database is not well organized.

1. Check the subquery to see if it is returning more than one row of data

  1. Identify the query that is returning more than one row of data.
  2. Check that the subquery is returning only the required data.
  3. If the subquery is returning more data than is needed, fix the query so that it is returning the required data.

2. If the subquery is only supposed to return one row, try adding a "LIMIT 1" clause to the end of the query

SELECT id FROM products LIMIT 1;

3. If the subquery is returning more than one row of data, make sure that the outer query is only expecting one row to be returned from the subquery

The outer query is expecting only one row to be returned from the subquery in order to fix the error code. To do this, the outer query can be modified to use the UNION ALL operator to combine the results of the subquery with the results of the main query.