如何获取行数作为列

Question

所以我有这样的查询

SELECT DISTINCT colB FROM tbl WHERE colA = "foo" LIMIT 0, 20

这给我一个最大数组 colA匹配"foo" 20条记录，但没有重复记录。 每个数组条目都包含一个包含colB值的关联数组，例如

0 => array(
       'colB' => 'some_value',
     ),
1 => array(
       'colB' => 'other_value',
     )

我还可以获取COUNT()作为colB值吗？ 我的意思是：

SELECT COUNT() as cbCount FROM tbl WHERE colA = "foo" AND colB = "some_value"
SELECT COUNT() as cbCount FROM tbl WHERE colA = "foo" AND colB = "other_value"

但是作为另一个数组字段包含在第一个查询中，例如：

0 => array(
       'colB' => 'some_value',
       'cbCount' => 5,
     ),
1 => array(
       'colB' => 'other_value',
       'cbCount' => 2,
     )

Answer 1

您需要做的就是使用GROUP BY子句

SELECT  colB,
        COUNT(colB) AS cbCount
FROM    tableName
WHERE   colA = 'Foo'
GROUP   BY colB

Answer 2

您需要将“ Group By依据”与“ Count配合使用-

SELECT 
        colB, count(colB) as cbCount
FROM    
        tbl 
WHERE  
        colA = 'foo' 
GROUP BY 
        colB 
LIMIT 
        0, 20

该查询将获取前20行，根据colB的不同值对它们进行colB并给出计数。