Function transformReturningList

src/backend/parser/analyze.c:2958–3002

* transformReturningList - * handle a RETURNING clause in INSERT/UPDATE/DELETE */

 *	handle a RETURNING clause in INSERT/UPDATE/DELETE
 */
static List *
transformReturningList(ParseState *pstate, List *returningList)
{
	List	   *rlist;
	int			save_next_resno;

	if (returningList == NIL)
		return NIL;				/* nothing to do */

	/*
	 * We need to assign resnos starting at one in the RETURNING list. Save
	 * and restore the main tlist's value of p_next_resno, just in case
	 * someone looks at it later (probably won't happen).
	 */
	save_next_resno = pstate->p_next_resno;
	pstate->p_next_resno = 1;

	/* transform RETURNING identically to a SELECT targetlist */
	rlist = transformTargetList(pstate, returningList, EXPR_KIND_RETURNING);

	/*
	 * Complain if the nonempty tlist expanded to nothing (which is possible
	 * if it contains only a star-expansion of a zero-column table).  If we
	 * allow this, the parsed Query will look like it didn't have RETURNING,
	 * with results that would probably surprise the user.
	 */
	if (rlist == NIL)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("RETURNING must have at least one column"),
				 parser_errposition(pstate,
									exprLocation(linitial(returningList)))));

	/* mark column origins */
	markTargetListOrigins(pstate, rlist);

	/* resolve any still-unresolved output columns as being type text */
	if (pstate->p_resolve_unknowns)
		resolveTargetListUnknowns(pstate, rlist);

	/* restore state */
	pstate->p_next_resno = save_next_resno;

	return rlist;
}


/*