Bulk Modify Table partition name (Oracle) ____oracle

--Bulk Modify the name of the table partition
DECLARE
V_sql VARCHAR2 (1000);
BEGIN
For X in (SELECT table_name, partition_name
From User_tab_partitions
WHERE to_date (SUBSTR (REPLACE (Partition_name, ' _ ', '),-6), ' Yy-mm-dd ' <
Add_months (TRUNC (sysdate, ' MONTH '), 0)
and table_name = ' t_unit_workinfo '
and partition_name like '%p_tbl_unit_workinfo_day_% ') LOOP
v_sql:= ' ALTER TABLE ' | | x.table_name| | ' RENAME PARTITION "' | | X.partition_name | | "To" ' | | ' P_tbl_unit_workinfo_20 ' | | To_char (To_date (SUBSTR (REPLACE (X.partition_name, ' _ ', '),-6), ' Yy-mm-dd '), ' YYMMDD ') | | '"';
EXECUTE IMMEDIATE V_sql;
End LOOP;
End;