ORA-14551: cannot perform a DML operation inside a query

Question

I have the following inside a package and it is giving me an error:

ORA-14551: cannot perform a DML operation inside a query

Answer 1

The meaning of the error is quite clear: if we call a function from a SELECT statement it cannot execute DML statements, that is INSERT, UPDATE or DELETE, or indeed DDL statements come to that.

Now, the snippet of code you have posted contains a call to PIPE ROW, so plainly you are calling this as SELECT * FROM TABLE(). But it includes DELETE and INSERT statements so clearly it falls foul of the purity levels required for functions in SELECT statements.

So, you need to remove those DML statements. You are using them to populate a global temporary table, but this is good news. You haven't include any code which actually uses the GTT so it is difficult to be sure, but using GTTs is often unnecessary. With more details we can suggest workarounds.

Is this related to this other question of yours? If so, did you follow my advice to check that answer I had given to a similar question?

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For the sake of completeness, it is possible to include DML and DDL statements in a function called in a SELECT statement. The workaround is to use the AUTONOMOUS_TRANSACTION pragma. This is rarely a good idea, and certainly wouldn't help in this scenario. Because the transaction is autonomous the changes it makes are invisible to the calling transaction. Meaning in this case that the function cannot see the outcome of the deletion or insertion in the GTT.