Mysql 根据多个条件进行选择

如果我们有两张这样的桌子

CREATE TABLE ta(`ID` int, `name` char(10));
INSERT INTO ta (`ID`, `name`)
VALUES
    (1, 'A'),
    (2, 'A'),
    (3, 'B'),
    (4, 'C'),
    (5, 'B');

CREATE TABLE yourtable(`ID` int, `Val` int);
INSERT INTO yourtable (`ID`, `Val`)
VALUES
    (1, 10),
    (1, 20),
    (1, 30),
    (1, 30),
    (2, 10),
    (2, 20),
    (3, 20),
    (3, 20),
    (4, 10),
    (4, 20),    
    (5, 10),
    (5, 20),
    (5, 30);

我需要使用两个表按名称对值进行分组。并且，对于条件val=10或val=30，它可以正常工作

但是，对于条件val=10和val=30我如何查询它？ 其中，输出应为

   Count
A  1
B  0
C  1

---

这里有一个例子：以name=A为例，我们得到ID=1,2。所以，现在在表yourtable中，我们有5行ID=1,2。对于ID=1，val=10,20,20。对于ID=2，val=10,20。这里只有ID=2满足val=10和val=30所以，对于name=A count=1

SELECT ta.name
     , COUNT(DISTINCT t2.val)
  FROM yourtable t1 
  LEFT
  JOIN yourtable t2
    ON t2.id = t1.id 
   AND t2.val IN (30) -- <-- things to exclude
  LEFT
  JOIN ta 
    ON ta.id = t1.id 
 WHERE t1.val IN (10) -- <-- things to include
 GROUP
    BY name;

NAME COUNT(T2.VAL)
A    1
B    1
C    0

您希望在表上有一个子查询来确定ID是否满足条件，并将其连接到ta

---

不是很好，但很有效：

SELECT name, max(occ) occurencies
  FROM (SELECT name, count(distinct t1.id) as occ
          FROM yourtable as t1, ta
         WHERE t1.id=ta.id
           AND val=10 
           AND NOT EXISTS (SELECT name 
                             FROM yourtable as t2 
                            WHERE t2.id=ta.id AND t2.val=30)
        GROUP BY name
        UNION
        SELECT name, 0 as occ
          FROM yourtable as t1, ta
         WHERE t1.id=ta.id
           AND val=10 
           AND EXISTS (SELECT name 
                         FROM yourtable as t2 
                        WHERE t2.id=ta.id AND t2.val=30)) as base
 GROUP BY name;

退房：

p、 美国：稍微好一点：

 SELECT ta.name, COALESCE (occ, 0)
   FROM ta
   LEFT JOIN (SELECT name, count(distinct t1.id) as occ
                FROM yourtable as t1, ta
               WHERE t1.id=ta.id
                 AND val=10 
                 AND NOT EXISTS (SELECT name 
                                   FROM yourtable as t2 
                                  WHERE t2.id=ta.id 
                                    AND t2.val=30)
               GROUP BY name) AS base ON (base.name = ta.name)
  GROUP BY name;    

---

：

奇怪的状况。如果val=10，则不能等于30，因此条件的第二部分没有意义，因此您所需的结果与条件不匹配。对于val=10，有2个A，1个B和1个C。这里有一个例子：以name=A为例，我们得到ID=1,2。所以，现在在表yourtable中，我们有5行ID=1,2。对于ID=1，val=10,20,20。对于ID=2，val=10,20。这里只有ID=2满足val=10和val=30所以，对于name=A count=1，这对我来说非常有意义！嗯，如果没有一些主键，可能很难提供一个确定的解决方案。您缺少用0打印空的。现在结果不匹配mmm不，B是0，C是1索引B是0，因为没有带val 10和val 30的B id，C有1，A有1，所以他的输出似乎符合逻辑。据我所知，只有在给定ID不包含数字30且确实包含数字10的情况下，他才会选择ID。通过您的更新，现在可以选择，但通过您的上一个小提琴，它没有选择，这可能是因为我不知道sqlfiddle是如何工作的，如果只运行查询的一部分，那么它提供的URL似乎只包含该部分

SELECT name, max(occ) occurencies
  FROM (SELECT name, count(distinct t1.id) as occ
          FROM yourtable as t1, ta
         WHERE t1.id=ta.id
           AND val=10 
           AND NOT EXISTS (SELECT name 
                             FROM yourtable as t2 
                            WHERE t2.id=ta.id AND t2.val=30)
        GROUP BY name
        UNION
        SELECT name, 0 as occ
          FROM yourtable as t1, ta
         WHERE t1.id=ta.id
           AND val=10 
           AND EXISTS (SELECT name 
                         FROM yourtable as t2 
                        WHERE t2.id=ta.id AND t2.val=30)) as base
 GROUP BY name;

 SELECT ta.name, COALESCE (occ, 0)
   FROM ta
   LEFT JOIN (SELECT name, count(distinct t1.id) as occ
                FROM yourtable as t1, ta
               WHERE t1.id=ta.id
                 AND val=10 
                 AND NOT EXISTS (SELECT name 
                                   FROM yourtable as t2 
                                  WHERE t2.id=ta.id 
                                    AND t2.val=30)
               GROUP BY name) AS base ON (base.name = ta.name)
  GROUP BY name;