Updating Table Columns Dynamically

Question

Hi Everybody,
I have created the following procedure to update table columns, which are having 'N/A' to Null.
PROCEDURE PRC_UPDATE_NA_TO_NULL (p_owner all_tables.owner%TYPE, p_table_name all_tables.table_name%TYPE DEFAULT NULL)
IS
TYPE tc_ref_cursor IS REF CURSOR;
v_tc_ref_cursor tc_ref_cursor;
TYPE nt_column_name IS TABLE OF all_tab_cols.column_name%TYPE;
v_nt_column_name nt_column_name;
v_table_name all_tables.table_name%TYPE;
v_set_str VARCHAR2(4000);
v_where_str VARCHAR2(4000);
v_sql_stmt VARCHAR2(4000);
BEGIN
IF p_table_name IS NOT NULL THEN
OPEN v_tc_ref_cursor FOR
SELECT a.table_name
FROM all_tables a
WHERE a.owner = UPPER(p_owner)
AND a.table_name = UPPER(p_table_name)
ORDER BY a.table_name;
ELSE
OPEN v_tc_ref_cursor FOR
SELECT a.table_name
FROM all_tables a
WHERE a.owner = UPPER(p_owner)
ORDER BY a.table_name;
END IF;
LOOP
DBMS_OUTPUT.PUT_LINE('Processing Owner : '||UPPER(p_owner)||'....');
FETCH v_tc_ref_cursor INTO v_table_name;
EXIT WHEN v_tc_ref_cursor%NOTFOUND;
SELECT b.column_name
BULK COLLECT INTO v_nt_column_name
FROM all_tab_cols b
WHERE b.owner = UPPER(p_owner)
AND b.table_name = UPPER(v_table_name)
AND b.nullable = 'Y'
ORDER BY b.column_id;
IF v_nt_column_name.LAST > 0 THEN
DBMS_OUTPUT.PUT_LINE('Updating '||v_table_name||'....');
FOR i IN v_nt_column_name.FIRST .. v_nt_column_name.LAST
LOOP
v_set_str := v_set_str||v_nt_column_name(i)||' := NULL, ';
v_where_str := v_where_str||v_nt_column_name(i)||' = '||'''N/A'''||' OR ';
END LOOP;
v_set_str := RTRIM(TRIM(v_set_str),',');
v_where_str := RTRIM(TRIM(v_where_str),'OR');
v_sql_stmt := 'UPDATE '||v_table_name||' SET '||v_set_str||' WHERE '||v_where_str;
EXECUTE IMMEDIATE v_sql_stmt;
-- EXECUTE IMMEDIATE 'UPDATE '||v_table_name||' SET '||v_set_str||' WHERE '||v_where_str;
-- EXECUTE IMMEDIATE 'UPDATE :1 SET :2 WHERE :3' USING v_table_name, v_set_str, v_where_str;
COMMIT;
v_set_str := NULL;
v_where_str := NULL;
DBMS_OUTPUT.PUT_LINE('Finished Updating '||v_table_name||'....');
END IF;
END LOOP;
DBMS_OUTPUT.PUT_LINE('Process Over....');
EXCEPTION
WHEN OTHERS THEN
ROLLBACK;
DBMS_OUTPUT.PUT_LINE(SQLCODE||':'||SQLERRM);
END;
The problem I am facing is that the Execute Immediate statement is not working. I have used the Execute Immediate statement in 3 different ways given in the above procedure, but none of them works and the error comes to the Exception section.
Kindly let me have your solutions.
Thanks in advance,
MAK

Answer 1

This approach can be dangerous. You are currently trying to update all columns in the tables to null if any of the columns are 'N/A'. Your query does not exclude external tables which may not be updatable. Your other query does not exclude data types that can not include 'N/A' such as number. You might want to move your commit outside the loop as you may end up committing partial updates.
You might try to capture the SQL that you are generating;
create table t(col2 varchar2(4000));Then in your package;
insert into t values(v_sql_stmt);
-- EXECUTE IMMEDIATE v_sql_stmt;