从按子查询分组的多个列中插入

Question

INSERT INTO TABLE (COLUMN_A, COLUMN_B, COLUMN_C)              -- Line 1
SELECT 'Label A',                                             -- Line 2
(SELECT CATEGORY, COUNT(1) FROM SUB_TABLE GROUP BY CATEGORY); -- Line 3, need help

第 3 行的结果

我想达到的目标

'Label A' 被插入到 COLUMN_A
从第 3 行按 CATEGORY 分组以插入到 COLUMN_B
从第 3 行按 COUNT(1) 分组以插入到 COLUMN_C

预期结果

我遇到错误：“子查询必须 return 只有一列”。怎样才能达到预期的效果？

Answer 1

如果想使用 subsqery，请尝试如下所示

INSERT INTO TABLE (COLUMN_A, COLUMN_B, COLUMN_C)              -
SELECT 'Label A', CATEGORY,  cnt from                                          
(SELECT CATEGORY, COUNT(1) as cnt FROM SUB_TABLE GROUP BY CATEGORY) a

其实不需要sub-query

 INSERT INTO TABLE (COLUMN_A, COLUMN_B, COLUMN_C)              -
SELECT 'Label A', CATEGORY,  COUNT(1) as cnt from                                          
  FROM SUB_TABLE GROUP BY CATEGORY

demo link

从按子查询分组的多个列中插入

Insert into Multiple Columns from a Grouped by Subquery

sql

subquery