mysql - 给出列表中存在但表中不存在的 ID

Question

我有一个像 (1,2,3,4,5,6) 这样的 ID 列表。我想找出列表中的这些 id 中有多少不存在于表中。我该怎么做呢 ？

-- table --
id    name
1     a
2     b
3     c   
4     d  
5     e 
6     f
7     g 

我得到的 ID 列表是 1,2,3,4,5,6,7,8,9,10,11,12,13

所以当查询我应该得到像 8,9,10,11,12,13 这样不在表中的结果

Answer 1

尝试这个：

SELECT 
  6-c
FROM (
  SELECT 
    COUNT(DISTINCT(ID)) as c 
  FROM 
    my_table 
  WHERE 
    ID IN (1,2,3,4,5,6)
) as tmp

并找出缺少哪些：

SELECT
    zID
FROM (
    SELECT 1 as zID UNION
    SELECT 2 as zID UNION
    SELECT 3 as zID UNION
    SELECT 4 as zID UNION
    SELECT 5 as zID UNION
    SELECT 6 as zID UNION
    SELECT 7 as zID UNION
    SELECT 8 as zID UNION
    SELECT 9 as zID UNION
    SELECT 10 as zID UNION
    SELECT 11 as zID UNION
    SELECT 12 as zID UNION
    SELECT 13 as zID UNION
    SELECT 14 as zID UNION
    SELECT 15 as zID UNION
) as t1
LEFT JOIN (
    SELECT 
        DISTINCT(ID) as mID 
    FROM 
        my_table 
) as t2
    ON t1.zID = t2.mID
WHERE
    t2.mID IS NULL

Answer 2

这将返回列表中不在表中的 ID 列表。

SELECT t1.id
FROM (SELECT 1 id
      UNION
      SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6) t1
LEFT JOIN MyTable t2
ON t1.id = t2.id
WHERE t2.id IS NULL

如果你经常做这样的事情，你可能想要创建一个包含常量的永久表，例如

CREATE TABLE numbers (id int primary key);
INSERT INTO numbers (id) VALUES (0), (1), (2), ..., (1000);

然后你可以这样做：

SELECT t1.id
FROM numbers
JOIN MyTable t2
ON t1.id = t2.id
WHERE t1.id IN (1, 2, 3, 4, 5, 6)
AND t2.id IS NULL