sql server

Question

Subquery returned more than 1 value. This is not permitted when the subquery

Naimish Makwana · Answer

The error "Subquery returned more than 1 value" occurs when a subquery (a query nested within another query) returns multiple values but the outer query expects only a single value. For example, consider the following query: SELECT Name FROM Students WHERE Age = (SELECT MAX(Age) FROM Students) Here, the subquery (SELECT MAX(Age) FROM Students) returns the maximum age of all the students, but if there are multiple students with the same maximum age, the subquery returns multiple values. If this happens, the outer query will fail with the error "Subquery returned more than 1 value." To fix this error, you can modify the subquery to return a single value. For example, you can add a TOP 1 clause to the subquery to return only the highest age: SELECT Name FROM Students WHERE Age = (SELECT TOP 1 MAX(Age) FROM Students) This will ensure that the subquery returns only a single value, allowing the outer query to execute successfully. Thanks Naimish Makwana

Tuhin Paul · Answer

You can also rewrite the query to use a join instead of a subquery. In some cases, using a join can provide better performance and avoid the error. If you expect the subquery to return multiple values, you can use the IN operator instead of =. Instead of WHERE col1 = (SELECT ...), you can use WHERE col1 IN (SELECT ...). This will allow the subquery to return multiple values and avoid the error.

Tuhin Paul · Answer

To fix the issue , Modify the subquery to return only a single value. For example, you can add a TOP 1 clause to the subquery to ensure that it returns only one row. Use a different type of subquery that returns a single value. You can use a scalar subquery, which returns a single value, rather than a table subquery, which can return multiple values.

Tuhin Paul · Answer

This error occurs when a subquery is used in a context where a single value is expected, but the subquery returns more than one value. If you are using a subquery in a WHERE clause to filter a result set based on a condition, the subquery should only return a single value. If the subquery returns more than one value, SQL Server cannot determine which value to use for the filter.