Question

我有两个表，第一个名为 table1 ：

ID  |  Name    |  Type | isActive | isDeleted | 
-----------------------------------------------
1   |  item 1  |  4    |  1       |  0        |
2   |  item 2  |  2    |  1       |  0        |
3   |  item 3  |  1    |  1       |  1        |
4   |  item 4  |  1    |  1       |  0        |
5   |  item 5  |  1    |  1       |  0        |
6   |  item 6  |  3    |  1       |  0        |
7   |  item 7  |  1    |  1       |  0        |
8   |  item 8  |  2    |  1       |  0        |
9   |  item 9  |  1    |  1       |  0        |
10  |  item 10 |  1    |  1       |  0        |

第二个名为 table1_meta ：

ID  |  table1_id  | options    | value
------------------------------------
1   |  1          | dont_ask   |  1   
2   |  2          | dont_ask   |  1
3   |  5          | dont_ask   |  1
4   |  6          | dont_ask   |  1
5   |  8          | alwasys_ask|  1
6   |  9          | alwasys_ask|  1
7   |  1          | is_flagged |  1
8   |  2          | is_flagged |  0
9   |  3          | is_flagged |  0
10  |  4          | is_flagged |  0
11  |  5          | is_flagged |  0
12  |  6          | is_flagged |  1
13  |  7          | is_flagged |  0
14  |  8          | is_flagged |  0
15  |  9          | is_flagged |  0
16  |  10         | is_flagged |  0

我正在尝试计算 table1 中符合某些特定条件的行，其中包括一些条件。

WHERE条件必须包含以下条件：

table1.type = 1 and table1.isActive = 1 and table1.isDeleted = 0 and table1_meta.options = 'is_flagged' and table1_meta.value = 0

和此：

table1_meta.options = 'dont_ask' and table1_meta.value = 1

和此：

table1_meta.options = 'always_ask' and table1_meta.value = 1

所以，我该怎么做？

SQLFiddle链接：http://sqlfiddle.com/#!2/2eb27b

感谢。

Answer 1

我假设您正在尝试计算第一个表中的行数。以下是使用子查询的一种方法：

select count(*)
from table1 t1
where t1.type = 1 and t1.isActive = 1 and t1.IsDeleted = 0 and
      exists (select 1
              from table1_meta tm
              where t1.id = tm.table1_id and tm.options = 'is_flagged' and tm.value = 0
             ) and
      not exists (select 1
                  from table1_meta tm
                  where t1.id = tm.table1_id and
                        tm.options = 'dont_ask' and tm.value = 1
                 ) and
      exists (select 1
              from table1_meta tm
              where t1.id = tm.table1_id and
                    tm.options = 'always_ask' and tm.value = 1
             );

这对元表上的每个条件都有一个单独的子查询。

Answer 2

我想我找到了问题的答案。

查询是：

SELECT Count(*) AS total FROM
        (SELECT Count(*)
        FROM   table1 t1,
               table1_meta t1meta
        WHERE  t1.type = 1
               AND t1.isactive = 1
               AND t1.isdeleted = 0
               AND t1meta.options = 'is_flagged'
               AND t1meta.value = 0
               AND t1.id NOT IN (SELECT table1_id
                                 FROM   table1_meta tm
                                 WHERE  tm.options = 'dont_ask'
                                        AND tm.value = 1)
        UNION
        SELECT Count(*)
        FROM   table1_meta tm,
               table1 t1
        WHERE  t1.id = tm.table1_id
               AND tm.options = 'always_ask'
               AND tm.value = 1) x

非常感谢，戈登。

MySQL - 使用某些条件计算主表中的行并等于特定值

2 个答案: