sql 基礎--mysql 5 （8）

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15.組合查詢 union

mysql> select uid,first_name,price from pw_price where uid >2 union select uid,first_name,price from pw_price where price>=1000;+-----+------------+-------+| uid | first_name | price |+-----+------------+-------+|   3 | li         |  2000 ||   2 | zhang      |  1000 |+-----+------------+-------+2 rows in set (0.00 sec)mysql> select uid,first_name,price from pw_price where uid >2 or price>=1000;+-----+------------+-------+| uid | first_name | price |+-----+------------+-------+|   2 | zhang      |  1000 ||   3 | li         |  2000 |+-----+------------+-------+2 rows in set (0.00 sec)

不去重顯示所有結果

mysql> select uid,first_name,price from pw_price where uid >2 union all select uid,first_name,prifrom pw_price where price>=1000;+-----+------------+-------+| uid | first_name | price |+-----+------------+-------+|   3 | li         |  2000 ||   2 | zhang      |  1000 ||   3 | li         |  2000 |+-----+------------+-------+3 rows in set (0.00 sec)

組合結果排序 放在最後的select語句中

mysql> select uid,first_name,price from pw_price where uid >2 union select uid,first_name,price from pw_price where price>=1000 order by uid desc;+-----+------------+-------+| uid | first_name | price |+-----+------------+-------+|   3 | li         |  2000 ||   2 | zhang      |  1000 |+-----+------------+-------+2 rows in set (0.00 sec)

 

sql 基礎--mysql 5 （8）