如何在单个 SQL 查询中使用多个计数和按条件分组

Posted 2023-03-24

【中文标题】如何在单个 SQL 查询中使用多个计数和按条件分组

【英文标题】：How to use multiple count and group by condition in single SQL query

【发布时间】：2015-04-10 04:56:29

【问题描述】：

下面是我的 SQL 表。

    Id   FileName       Code1    Code2
    1   002-03_001.tif  Y179     Y179
    2   002-03_002.tif  Y178     Y178
    3   002-03_003.tif  Y177     Y177
    4   002-03_004.tif  Y178     Y179
    5   002-03_005.tif  Y177     Y179
    6   002-03_006.tif  Y179     Y178
    7   002-03_007.tif  Y178     Y178
    8   002-03_008.tif  Y178     Y177
    9   002-03_009.tif  Y177     Y179
    10  002-03_010.tif  Y178     Y177

从上表中我想计算 Code1 和 code2 之类的，

  Code1 Count1 Code2 Count2
  Y177   3      Y177    3
  Y178   2      Y178    3
  Y179   5      Y179    4

【参考方案1】：

你想做这样的事情 SQL Fiddle

样本数据

create table table1
(
Id int,FileName VARCHAR(100),Code1 VARCHAR(10),Code2 VARCHAR(10)
)

insert into table1 values(    1,   '002-03_001.tif',  'Y179',     'Y179'),
    (2   ,'002-03_002.tif',  'Y178',     'Y178')
    ,(3   ,'002-03_003.tif',  'Y177',     'Y177')
    ,(4   ,'002-03_004.tif',  'Y178',     'Y179')
    ,(5   ,'002-03_005.tif',  'Y177',     'Y179')
    ,(6   ,'002-03_006.tif',  'Y179',     'Y178')
    ,(7   ,'002-03_007.tif',  'Y178',     'Y178')
    ,(8   ,'002-03_008.tif',  'Y178',     'Y177')
    ,(9   ,'002-03_009.tif',  'Y177',     'Y179')
    ,(10  ,'002-03_010.tif',  'Y178',     'Y177')

查询

SELECT * FROM
(
    SELECT Code1,COUNT(*) Count1
    FROM table1
    GROUP BY Code1
)   Code1
INNER JOIN 
(
    SELECT Code2,COUNT(*) Count2
    FROM table1
    GROUP BY Code2
) Code2
ON Code1.Code1 = Code2.Code2