CREATE OR REPLACE FUNCTION ColumnAlreadyExists(name, name) RETURNS INTEGER AS E'
DECLARE columnCount INTEGER;
BEGIN
SELECT COUNT (pg_attribute.attname) into columnCount FROM pg_attribute,pg_class, pg_type WHERE ((pg_attribute.attrelid=pg_class.oid) AND (pg_attribute.atttypid=pg_type.oid) AND (pg_class.relname = $1) AND (pg_attribute.attname = $2));
IF columnCount = 0 THEN
RETURN 0;
END IF;
RETURN 1;
END;
' LANGUAGE 'plpgsql';
DROP FUNCTION checkColumn(name,name,name);
CREATE OR REPLACE FUNCTION checkColumn(name, name, name) RETURNS name AS E'
DECLARE isColumnExist INTEGER;
BEGIN
SELECT ColumnAlreadyExists ($1,$2) into isColumnExist;
IF isColumnExist = 0 THEN
RETURN name($3);
ELSE
RETURN name($2);
END IF;
END;
' LANGUAGE 'plpgsql';
Function checkColumn should return proper column name (second parameter) if column exist and third parameter if column not exist.
NOW when I try to execute following command it returns improper result.
I expect proper column values as a output of query.
SELECT(checkColumn('tbl','c2','0'))::name FROM tbl;
mydb=# SELECT (checkColumn('tbl','c2','0'))::name FROM tbl;
checkcolumn
-------------
c2
c2
c2
c2
c2
c2
c2
c2
(8 rows)
mydb=#
Above query should return actual values present for c2 column in tbl.
But it’s not working as desired.
Please help me in this.
Thanks in advance,
Santosh.
