MySQL组字段及其值

假设我有一个表调用客户端。 在此表中，我有3个字段（A、B、C） 当A=B=C时，我想对每行进行分组 例：

我想得到以下信息

(A,B,C)   otherRow  Count
    1     x         2
    2     x         2
    2     y         1
    3     x         1
    4     y         1

---

您的查询是

UNION

，而不是

JOIN

：

SELECT 
  `A,B,C`, 
  otherRow, 
  COUNT(`A,B,C`) AS `Count`
FROM
  (SELECT a AS `A,B,C`, otherRow FROM t
  UNION ALL
  SELECT b AS `A,B,C`, otherRow FROM t
  UNION ALL
  SELECT c AS `A,B,C`, otherRow FROM t) AS u
GROUP BY
  `A,B,C`,
  otherRow
HAVING
  `A,B,C` IS NOT NULL

---

看看这个。我添加了

NULL

-检查，因为您的“空”值不明显。如果删除它，将得到零计数的空行。

您的查询是

UNION

，而不是

JOIN

：

SELECT 
  `A,B,C`, 
  otherRow, 
  COUNT(`A,B,C`) AS `Count`
FROM
  (SELECT a AS `A,B,C`, otherRow FROM t
  UNION ALL
  SELECT b AS `A,B,C`, otherRow FROM t
  UNION ALL
  SELECT c AS `A,B,C`, otherRow FROM t) AS u
GROUP BY
  `A,B,C`,
  otherRow
HAVING
  `A,B,C` IS NOT NULL

---

看看这个。我添加了

NULL

-检查，因为您的“空”值不明显。如果删除它，将得到零计数的空行。

您的查询是

UNION

，而不是

JOIN

：

SELECT 
  `A,B,C`, 
  otherRow, 
  COUNT(`A,B,C`) AS `Count`
FROM
  (SELECT a AS `A,B,C`, otherRow FROM t
  UNION ALL
  SELECT b AS `A,B,C`, otherRow FROM t
  UNION ALL
  SELECT c AS `A,B,C`, otherRow FROM t) AS u
GROUP BY
  `A,B,C`,
  otherRow
HAVING
  `A,B,C` IS NOT NULL

---

看看这个。我添加了

NULL

-检查，因为您的“空”值不明显。如果删除它，将得到零计数的空行。

您的查询是

UNION

，而不是

JOIN

：

SELECT 
  `A,B,C`, 
  otherRow, 
  COUNT(`A,B,C`) AS `Count`
FROM
  (SELECT a AS `A,B,C`, otherRow FROM t
  UNION ALL
  SELECT b AS `A,B,C`, otherRow FROM t
  UNION ALL
  SELECT c AS `A,B,C`, otherRow FROM t) AS u
GROUP BY
  `A,B,C`,
  otherRow
HAVING
  `A,B,C` IS NOT NULL

看看这个。我添加了

NULL

-检查，因为您的“空”值不明显。如果删除它，将得到零计数的空行