You may want to drop already existing table:
DROP TABLE items_backup;
Now duplicate structure and copy data from basic table
CREATE TABLE items_backup LIKE items; INSERT INTO items_backup SELECT * FROM items;
You may want to add primary key:
ALTER TABLE items ADD PRIMARY KEY (item_id [,item_mf_id])
or unique constraint
ALTER TABLE EMPLOYEE ADD CONSTRAINT NEWID UNIQUE(EMPNO,HIREDATE)
and indexes
CREATE UNIQUE INDEX UNIQUE_NAM ON items (item_name) CREATE INDEX JOB_BY_DPT ON items (item_name, item_category)