Oracle batch Modify Table Field Types

In Oracle, changing the CHAR fields in all tables under the table field type tablespace to VARCHAR2 in batches is too many data table fields. It is too troublesome to change the fields one by one, so I thought of the following method: [SQL] DECLARE CURSOR TEMP IS SELECT TABLE_NAME, COLUMN_NAME, DATA_LENGTH FROM USER_TAB_COLUMNS WHERE DATA_TYPE = 'Char '; STR VARCHAR2 (100): = ''; BEGIN FOR S IN TEMP LOOP STR: = 'alter table' | S. TABLE_NAME | 'modify ('| S. COLUMN_NAME | 'varchar2 ('| S. DATA_LENGTH | ')'; DBMS_OUTPUT.PUT_LINE (STR); execute immediate str; end loop; END;