用to_date只更新年份.txt

orale培训教材包括了所有的sql说明和实例

---只更新年份err!

UPDATE plsql101_product
SET    last_stock_date 
= TO_DATE('2000',
          'yyyy');

UPDATE plsql101_product
SET    last_stock_date 
= TO_DATE('2002',
          'yyyy')
where to_char(last_stock_date,'yyyy')='2000'
--对吗?--月日被变为本月第一天
INSERT INTO plsql101_product VALUES 
     ('Small Widget', 99, 1, '15-1月-03');

INSERT INTO plsql101_product VALUES 
     ('Small Widget', 99, 1, '15-1月-02');

INSERT INTO plsql101_product VALUES 
     ('Small Widget', 99, 1, '15-1月-00');




SELECT product_name, 
       product_price,
       quantity_on_hand,
       TO_CHAR(last_stock_date, 'MM-DD-YYYY HH24:MI') 
FROM   plsql101_product; 

--必须用to_char与年份连接在一起再套用to_date
--注意格式一致！
UPDATE plsql101_product
SET    last_stock_date 
= TO_DATE('2002/' || to_char(last_stock_date,'mm/dd'),
          'yyyy/mm/dd')
where to_char(last_stock_date,'yyyy')='2002'