


Update with Join Query in Oracle
An Oracle user encountered an unending execution time for the following query:
UPDATE table1 t1 SET (t1.col,t1.Output) = ( SELECT t2.col, t3.Output + t2.col FROM tabl2 t3 LEFT JOIN table1 t2 ON t3.Join_Key = t2.Join_Key WHERE t2.col is not NULL);
Unless the SELECT subquery guarantees a single-row result, the UPDATE statement will fail with the error:
ORA-01427: single-row subquery returns more than one row
Correlated updates require a condition linking rows in the outer table (table1 in this case) and the inner subquery. Typically, this condition appears:
AND t1.some_key = t2.some_key);
Additionally, the query updates every row in table1. If the user intends to update specific rows, a WHERE clause that filters based on the join condition should be added, such as:
... WHERE subquery_condition
The above is the detailed content of How Can I Fix ORA-01427 in My Oracle UPDATE Statement with a JOIN Subquery?. For more information, please follow other related articles on the PHP Chinese website!

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