Do you know there is a limitation of sub-query in Oracle? If you don’t know then keep in mind the following limitation.
There is a limitation of Oracle for Subqueries. You can use unlimited sub-queries in the FROM clause of the main query. You can use a maximum 255 sub-queries in the WHERE clause of Oracle. This limitation is the same in Oracle 10g and Oracle 11g. There is no change of this sub-query limitation in both Oracle versions.
Beware of using more sub-queries in WHERE clause of the main query.
Thanks and regards,
Remote DBA Team