mysql> SELECT name, birth FROM mytable ORDER BY birth; +----------+------------+ | name | birth | +----------+------------+ | tom | 1973-09-02 | | abccs | 1977-07-07 | | mary | 1978-12-12 | +----------+------------+ 3 row in set (0.00 sec) |
我們可以用DESC來進行逆序排序：
mysql> SELECT name, birth FROM mytable ORDER BY birth DESC; +----------+------------+ | name | birth | +----------+------------+ | mary | 1978-12-12 | | abccs | 1977-07-07 | | tom | 1973-09-02 | +----------+------------+ 3 row in set (0.00 sec) |
7、 行計數
數據庫經常要統計一些數據，如表中員工的數目，我們就要用到行計數函數COUNT()。COUNT()函數用于對非NULL結果的記錄進行計數：
mysql> SELECT COUNT(*) FROM mytable; +----------+ | COUNT(*) | +----------+ | 3 | +----------+ 1 row in set (0.06 sec) 員工中男女數量： mysql> SELECT sex, COUNT(*) FROM mytable GROUP BY sex; +------+----------+ | sex | COUNT(*) | +------+----------+ | f | 2 | | m | 1 | +------+----------+ 2 row in set (0.00 sec) |
注意我們使用了GROUP BY對SEX進行了分組。