mysql select语句操作实例(2)

SELECT college, region, seed FROM tournament  ORDER BY region, seed;
SELECT college, region AS r, seed AS s FROM tournament ORDER BY r, s;
SELECT college, region, seed FROM tournament  ORDER BY 2, 3;

--要以相反的顺序进行分类，应把DESC（降序）关键字添加到ORDER BY子句中的列名称中。默认值为升序；该值可以使用ASC关键词明确地指定。
SELECT a, COUNT(b) FROM test_table ORDER BY a DESC；

GROUP BY查询

复制代码 代码如下:

SELECT a, COUNT(b) FROM test_table GROUP BY a DESC；
SELECT COUNT(col1) AS col2 FROM t GROUP BY col2 HAVING col2 = 2;