php - Mysql汇总包含两列之一中的值的所有行

Question

我有一个表，它的搜索值可能位于两列之一，即 B 列和/或 C 列。我想根据 A 列生成一个摘要，显示所选搜索值（例如 x）出现在每个人的任一列。我想计算两列的总数。

+--------+------+----+
|  name  | B    | C  |
+--------+------+----+ 
| john   | x    | z  |
| john   | x    | x  |
| john   | y    | x  |
| peter  | x    | z  |
| peter  | x    | z  |
| amanda | x    | x  |
| amanda | x    | x  |
| amanda | x    | x  |
| amanda | x    | y  |
| amanda | x    | y  |
+--------+-----------+

在上面的示例中，假设我的搜索值为 x，我想计算 x 在 B 列和/或 C 列中每个人出现的次数。我还想产生总计，并产生以下输出：

Name   B  C

john   2  2
peter  2  0
amanda 5  3
total  9  5

我可以像这样单独为每一列执行此操作：

     SELECT name, COUNT(*) as count FROM table 
          WHERE A = 'x'
          GROUP BY name
          ORDER BY count DESC";

     SELECT name, COUNT(*) as count FROM table 
          WHERE B = 'x'
          GROUP BY name
          ORDER BY count DESC";

然后我可以循环对每个输出进行单独的提取并将它们组合起来，但是我想知道是否有一种方法可以在一个 mysql 语句中对两列进行检查和计数？

Answer 1

如果您想要分别计算每列的总和，则可以使用以下命令（SQL Fiddle）：

(
  SELECT MTA.Name, Sum(MTA.B = 'x') AS BSum, Sum(MTA.C = 'x') AS CSum
  FROM MyTable MTA
  GROUP BY MTA.Name
)
UNION
(
  SELECT 'Total' AS name, Sum(MTB.B = 'x') AS BSum, Sum(MTB.C = 'x') AS CSum
  FROM MyTable AS MTB
)

或者，如果您想要合并两列的总和，那么您可以执行以下操作（SQL Fiddle）：

(
  SELECT MTA.Name, Sum(MTA.B = 'x') + Sum(MTA.C = 'x') AS PersonTotal
  FROM MyTable MTA
  GROUP BY MTA.Name
)
UNION
(
  SELECT 'Total' AS name, Sum(MTB.B = 'x') + Sum(MTB.C = 'x') AS PersonTotal
  FROM MyTable AS MTB
)

Answer 2

select...
case count (when A = 'x' then A else null) end,
case count (when B = 'x' then B else null) end
...

编辑：哎呀，忽略了计数...

Answer 3

SELECT name, 
COUNT(CASE WHEN B='x' THEN 1 ELSE 0 END) as B,
COUNT(CASE WHEN C='x' THEN 1 ELSE 0 END) as C FROM table 
GROUP BY name;

Answer 4

SELECT name, sum(if(B='x',1,0)) as c1, sum(if(C='x',1,0)) as c2FROM table 
WHERE A = 'x'
GROUP BY name
ORDER BY c1 desc, c2 desc

Answer 5

MySQL 快捷方式，

SELECT Name,
       SUM(B='x') TotalX,
       SUM(C='x') TotalY
FROM   TableName
GROUP  BY Name