根据其他频率从一个表中选择列？

Question

如何根据其他表中其他列的频率

从一个表中选择列

示例：

Table 1

sr.     id
1       37
2       45
3       56
3       69
2       25

Table 2

id
37
45
56
56
56
45
69

预期结果

sr    count
1      1
2      2
3      4

现在我需要按sr中其ID的频率顺序选择table 2。

Answer 1

以下查询可以完成您想要的任务：

SELECT 
  Table1.sr,
  COUNT(*) total
FROM Table1 
INNER JOIN Table2
ON Table1.id = Table2.id
GROUP BY Table1.sr
ORDER BY total;

更多

以防万一，如果您想要sr中的所有table1，无论table2中是否存在相应的ID，那么您需要使用LEFT JOIN。< / p>

所以，这里是基于这种情况的修改过的查询：

SELECT 
Table1.sr,
COUNT(Table2.id) total
FROM Table1 
LEFT JOIN Table2
ON Table1.id = Table2.id
GROUP BY Table1.sr
ORDER BY total;

Answer 2

这样的事情：

SELECT t1.sr, t1.id
FROM table1 AS t1
JOIN (
   SELECT id, COUNT(*) AS cnt
   FROM table2
   GROUP BY id
) AS t2 ON t1.id = t2.id
ORDER BY t2.cnt DESC

Answer 3

select t1.sr,count(*)
from take1 t1
inner join take2 t2 on t1.id =t2.id
group by t1.sr