order by嵌套子查询问题

yinaoxiao7661 2017-04-07 09:24:15
两张表,一张supply表,一张tree表,我要查询所有的supply中的信息,但是要根据tree表中的treename排序;



单独查没有问题,嵌套在一起就出现子查询超过一行的问题,请问怎么解决??
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二月十六 版主 2017-04-08
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引用 19 楼 yinaoxiao7661 的回复:
看着对劲啊。。。
gw6328 2017-04-07
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order by treename 就是最正常的一种方式。 但是看楼主不是想要这个,你是想要treename的数量来排序? 那你试一下这个 ;with cte as ( select * from xxx ,xxx from xxxxxx --你上面个查询 ) ,c1 as ( select count(*) as ct ,treename from xxxxx --你下面个查询 ) select * from cte a join c1 b on a.treename=b.treename order by b.ct desc;
yinaoxiao7661 2017-04-07
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引用 18 楼 sinat_28984567 的回复:
[quote=引用 17 楼 yinaoxiao7661 的回复:]
[quote=引用 16 楼 sinat_28984567 的回复:]
[quote=引用 15 楼 yinaoxiao7661 的回复:]
你这个是用什么写的?看不懂啊,我只会用MySQL


就是为了测试方便用mssql写的,语句是一样的,改一下表名字就行了。试试这个
SELECT  *
FROM supply a
JOIN tree b ON a.treeId = b.treeId
JOIN ( SELECT supply.treeId ,
COUNT(1) AS num
FROM supply
JOIN tree ON supply.treeId = tree.treeId
GROUP BY supply.treeId
) t ON b.treeId = t.treeId
ORDER BY t.num DESC
[/quote]
不行,排序是乱的
[/quote]

把得到的num列出来看一下[/quote]
yinaoxiao7661 2017-04-07
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引用 5 楼 sinat_28984567 的回复:
写漏了一个group by 试试这个
SELECT  a.* ,
b.*
FROM supply a
JOIN tree b ON a.treeid = b.treeid
JOIN ( SELECT treename ,
COUNT(treename) AS num
FROM supply
JOIN tree ON supply.treeid = tree.treeid
GROUP BY treename
) t ON b.treename = t.treename
ORDER BY t.num

还是不行,加上group by 排序是乱的
二月十六 版主 2017-04-07
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写漏了一个group by 试试这个
SELECT  a.* ,
        b.*
FROM    supply a
        JOIN tree b ON a.treeid = b.treeid
        JOIN ( SELECT   treename ,
                        COUNT(treename) AS num
               FROM     supply
                        JOIN tree ON supply.treeid = tree.treeid
               GROUP BY treename
             ) t ON b.treename = t.treename
ORDER BY t.num
yinaoxiao7661 2017-04-07
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引用 3 楼 sinat_28984567 的回复:
试试这个
SELECT  a.* ,
b.*
FROM supply a
JOIN tree b ON a.treeid = b.treeid
JOIN ( SELECT treename ,
COUNT(treename) AS num
FROM supply
JOIN tree ON supply.treeid = tree.treeid
) t ON b.treename = t.treename
ORDER BY t.num

不行啊,结果只有一棵树的数据,其他的怎么没有
二月十六 版主 2017-04-07
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试试这个
SELECT  a.* ,
        b.*
FROM    supply a
        JOIN tree b ON a.treeid = b.treeid
        JOIN ( SELECT   treename ,
                        COUNT(treename) AS num
               FROM     supply
                        JOIN tree ON supply.treeid = tree.treeid
             ) t ON b.treename = t.treename
ORDER BY t.num
yinaoxiao7661 2017-04-07
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引用 楼主 yinaoxiao7661 的回复:
两张表,一张supply表,一张tree表,我要查询所有的supply中的信息,但是要根据tree表中的treename排序; 单独查没有问题,嵌套在一起就出现子查询超过一行的问题,请问怎么解决??
supply表和tree表连接查询,查询结果根据查询出来的treename分组统计数量,按数量倒序排序;意思就是查询结果按树木的供应数量倒序排序
卖水果的net 版主 2017-04-07
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你这是要按什么排序啊? 说一下需求吧;
二月十六 版主 2017-04-07
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引用 17 楼 yinaoxiao7661 的回复:
[quote=引用 16 楼 sinat_28984567 的回复:] [quote=引用 15 楼 yinaoxiao7661 的回复:] 你这个是用什么写的?看不懂啊,我只会用MySQL
就是为了测试方便用mssql写的,语句是一样的,改一下表名字就行了。试试这个
SELECT  *
FROM    supply a
        JOIN tree b ON a.treeId = b.treeId
        JOIN ( SELECT   supply.treeId ,
                        COUNT(1) AS num
               FROM     supply
                        JOIN  tree ON supply.treeId = tree.treeId
               GROUP BY supply.treeId
             ) t ON b.treeId = t.treeId
ORDER BY t.num DESC
[/quote] 不行,排序是乱的 [/quote] 把得到的num列出来看一下
yinaoxiao7661 2017-04-07
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引用 16 楼 sinat_28984567 的回复:
[quote=引用 15 楼 yinaoxiao7661 的回复:]
你这个是用什么写的?看不懂啊,我只会用MySQL


就是为了测试方便用mssql写的,语句是一样的,改一下表名字就行了。试试这个
SELECT  *
FROM supply a
JOIN tree b ON a.treeId = b.treeId
JOIN ( SELECT supply.treeId ,
COUNT(1) AS num
FROM supply
JOIN tree ON supply.treeId = tree.treeId
GROUP BY supply.treeId
) t ON b.treeId = t.treeId
ORDER BY t.num DESC
[/quote]
不行,排序是乱的
二月十六 版主 2017-04-07
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引用 15 楼 yinaoxiao7661 的回复:
你这个是用什么写的?看不懂啊,我只会用MySQL
就是为了测试方便用mssql写的,语句是一样的,改一下表名字就行了。试试这个
SELECT  *
FROM    supply a
        JOIN tree b ON a.treeId = b.treeId
        JOIN ( SELECT   supply.treeId ,
                        COUNT(1) AS num
               FROM     supply
                        JOIN  tree ON supply.treeId = tree.treeId
               GROUP BY supply.treeId
             ) t ON b.treeId = t.treeId
ORDER BY t.num DESC
yinaoxiao7661 2017-04-07
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引用 14 楼 sinat_28984567 的回复:
用mssql写的测试数据好弄。语句应该差不多。楼主参考一下。
--测试数据
if not object_id(N'Tempdb..#supply') is null
	drop table #supply
Go
Create table #supply([supplyid] int,[treeTypeID] int,[treeId] int,[userId] int,[releaseTIme] Date,[validityPeriod] Date,[supplyDescribe] nvarchar(27),[supplyPlace] nvarchar(22),[supplySum] int)
Insert #supply
select 1,1,1,1,'2017-3-14','2017-8-14',N'桂花、香樟',N'江苏',2000 union all
select 10,2,1,5,'2017-3-30','2017-8-22',N'光叶白兰、连翘',N'山东',2200 union all
select 11,3,2,1,'2017-3-31','2017-8-23',N'青桐、光叶白兰',N'天津',2300 union all
select 12,3,3,2,'2017-3-22','2017-8-24',N'枫杨、青桐',N'江西',2400 union all
select 13,3,3,3,'2017-3-24','2017-8-25',N'意杨、枫杨',N'福建',2500 union all
select 14,3,3,4,'2017-3-25','2017-8-26',N'丰花月季、意杨',N'四川',2600 union all
select 15,3,3,5,'2017-3-23','2017-8-27',N'红枫、丰花月季',N'重庆',2700 union all
select 16,4,4,1,'2017-3-19','2017-8-28',N'侧柏、红枫',N'北京',2800 union all
select 17,4,4,2,'2017-3-13','2017-8-29',N'竹柏、侧柏',N'江苏',2900 union all
select 18,4,4,3,'2017-3-26','2017-8-30',N'柳杉、竹柏',N'浙江',3000 union all
select 19,4,4,4,'2017-3-10','2017-8-13',N'国槐、柳杉',N'安徽',3100 union all
select 2,1,1,2,'2017-3-15','2017-8-29',N'梅花、香樟',N'浙江',1000 union all
select 20,4,4,5,'2017-3-11','2017-8-12',N'白蜡树、国槐',N'湖南',3200 union all
select 21,5,5,1,'2017-3-12','2017-8-11',N'落羽松、雪松',N'湖北',3300 union all
select 22,5,5,2,'2017-3-13','2017-8-10',N'雪松、国槐',N'上海',3400 union all
select 23,5,5,3,'2017-3-9','2017-8-9',N'罗汉松、白蜡树',N'河北',3500 union all
select 24,5,5,4,'2017-3-8','2017-8-8',N'木荷、罗汉松',N'河南',3500 union all
select 25,5,5,5,'2017-3-7','2017-8-7',N'樱花、木荷',N'海南',3000 union all
select 26,2,2,6,'2017-4-8','2017-9-8',N'连翘、法桐',N'江苏',10000 union all
select 3,1,1,3,'2017-3-21','2017-8-15',N'桂花、棕榈',N'安徽',1500 union all
select 4,1,1,4,'2017-3-20','2017-8-16',N'红花槐、棕榈',N'湖南',1600 union all
select 5,1,1,5,'2017-3-18','2017-8-17',N'桢楠、红花槐',N'湖北',1700 union all
select 6,2,2,1,'2017-3-17','2017-8-18',N'池杉、桢楠',N'上海',1800 union all
select 7,2,2,2,'2017-3-28','2017-8-19',N'木槿、海滨木槿',N'河北',1900 union all
select 8,2,2,3,'2017-3-27','2017-8-20',N'法桐、桢楠',N'河南',2000 union all
select 9,2,2,4,'2017-3-29','2017-8-21',N'连翘、法桐',N'山西',2100
GO
if not object_id(N'Tempdb..#tree') is null
	drop table #tree
Go
Create table #tree([treeId] int,[treeTypeId] int,[treeName] nvarchar(23))
Insert #tree
select 1,1,N'落羽松' union all
select 2,1,N'金钱松' union all
select 3,1,N'水杉' union all
select 4,1,N'池杉' union all
select 5,1,N'法桐'
Go
--测试数据结束
SELECT  *
FROM    #supply a
        JOIN #tree b ON a.treeId = b.treeId
        JOIN ( SELECT   #supply.treeId ,
                        COUNT(1) AS num
               FROM     #supply
                        JOIN #tree ON #supply.treeId = #tree.treeId
               GROUP BY #supply.treeId
             ) t ON b.treeId = t.treeId
ORDER BY t.num DESC
你这个是用什么写的?看不懂啊,我只会用MySQL
二月十六 版主 2017-04-07
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用mssql写的测试数据好弄。语句应该差不多。楼主参考一下。
--测试数据
if not object_id(N'Tempdb..#supply') is null
drop table #supply
Go
Create table #supply([supplyid] int,[treeTypeID] int,[treeId] int,[userId] int,[releaseTIme] Date,[validityPeriod] Date,[supplyDescribe] nvarchar(27),[supplyPlace] nvarchar(22),[supplySum] int)
Insert #supply
select 1,1,1,1,'2017-3-14','2017-8-14',N'桂花、香樟',N'江苏',2000 union all
select 10,2,1,5,'2017-3-30','2017-8-22',N'光叶白兰、连翘',N'山东',2200 union all
select 11,3,2,1,'2017-3-31','2017-8-23',N'青桐、光叶白兰',N'天津',2300 union all
select 12,3,3,2,'2017-3-22','2017-8-24',N'枫杨、青桐',N'江西',2400 union all
select 13,3,3,3,'2017-3-24','2017-8-25',N'意杨、枫杨',N'福建',2500 union all
select 14,3,3,4,'2017-3-25','2017-8-26',N'丰花月季、意杨',N'四川',2600 union all
select 15,3,3,5,'2017-3-23','2017-8-27',N'红枫、丰花月季',N'重庆',2700 union all
select 16,4,4,1,'2017-3-19','2017-8-28',N'侧柏、红枫',N'北京',2800 union all
select 17,4,4,2,'2017-3-13','2017-8-29',N'竹柏、侧柏',N'江苏',2900 union all
select 18,4,4,3,'2017-3-26','2017-8-30',N'柳杉、竹柏',N'浙江',3000 union all
select 19,4,4,4,'2017-3-10','2017-8-13',N'国槐、柳杉',N'安徽',3100 union all
select 2,1,1,2,'2017-3-15','2017-8-29',N'梅花、香樟',N'浙江',1000 union all
select 20,4,4,5,'2017-3-11','2017-8-12',N'白蜡树、国槐',N'湖南',3200 union all
select 21,5,5,1,'2017-3-12','2017-8-11',N'落羽松、雪松',N'湖北',3300 union all
select 22,5,5,2,'2017-3-13','2017-8-10',N'雪松、国槐',N'上海',3400 union all
select 23,5,5,3,'2017-3-9','2017-8-9',N'罗汉松、白蜡树',N'河北',3500 union all
select 24,5,5,4,'2017-3-8','2017-8-8',N'木荷、罗汉松',N'河南',3500 union all
select 25,5,5,5,'2017-3-7','2017-8-7',N'樱花、木荷',N'海南',3000 union all
select 26,2,2,6,'2017-4-8','2017-9-8',N'连翘、法桐',N'江苏',10000 union all
select 3,1,1,3,'2017-3-21','2017-8-15',N'桂花、棕榈',N'安徽',1500 union all
select 4,1,1,4,'2017-3-20','2017-8-16',N'红花槐、棕榈',N'湖南',1600 union all
select 5,1,1,5,'2017-3-18','2017-8-17',N'桢楠、红花槐',N'湖北',1700 union all
select 6,2,2,1,'2017-3-17','2017-8-18',N'池杉、桢楠',N'上海',1800 union all
select 7,2,2,2,'2017-3-28','2017-8-19',N'木槿、海滨木槿',N'河北',1900 union all
select 8,2,2,3,'2017-3-27','2017-8-20',N'法桐、桢楠',N'河南',2000 union all
select 9,2,2,4,'2017-3-29','2017-8-21',N'连翘、法桐',N'山西',2100
GO
if not object_id(N'Tempdb..#tree') is null
drop table #tree
Go
Create table #tree([treeId] int,[treeTypeId] int,[treeName] nvarchar(23))
Insert #tree
select 1,1,N'落羽松' union all
select 2,1,N'金钱松' union all
select 3,1,N'水杉' union all
select 4,1,N'池杉' union all
select 5,1,N'法桐'
Go
--测试数据结束
SELECT *
FROM #supply a
JOIN #tree b ON a.treeId = b.treeId
JOIN ( SELECT #supply.treeId ,
COUNT(1) AS num
FROM #supply
JOIN #tree ON #supply.treeId = #tree.treeId
GROUP BY #supply.treeId
) t ON b.treeId = t.treeId
ORDER BY t.num DESC





gw6328 2017-04-07
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引用 11 楼 yinaoxiao7661 的回复:
[quote=引用 7 楼 jinfengyiye 的回复:] order by treename 就是最正常的一种方式。 但是看楼主不是想要这个,你是想要treename的数量来排序? 那你试一下这个 ;with cte as ( select * from xxx ,xxx from xxxxxx --你上面个查询 ) ,c1 as ( select count(*) as ct ,treename from xxxxx --你下面个查询 ) select * from cte a join c1 b on a.treename=b.treename order by b.ct desc;
对,我是想通过统计查询结果中treename的数量来排序,我看了下你这种查询方式我不太懂,复制粘贴后查询报错 [/quote] 我这个是mssql 没注意看到你说的是mysql ,mysql应该可以用扩展表吧。你把 cte 和 c1 直接用两个()包起来 select * from (第一个查询) a join (第二个查询) b on a.treename=b.treename order by b.ct desc;
yinaoxiao7661 2017-04-07
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引用 8 楼 sinat_28984567 的回复:
贴点测试数据,我自己建表试试

supply表:

1 1 1 1 2017-3-14 2017-8-14 桂花、香樟 江苏 2000
10 2 1 5 2017-3-30 2017-8-22 光叶白兰、连翘 山东 2200
11 3 2 1 2017-3-31 2017-8-23 青桐、光叶白兰 天津 2300
12 3 3 2 2017-3-22 2017-8-24 枫杨、青桐 江西 2400
13 3 3 3 2017-3-24 2017-8-25 意杨、枫杨 福建 2500
14 3 3 4 2017-3-25 2017-8-26 丰花月季、意杨 四川 2600
15 3 3 5 2017-3-23 2017-8-27 红枫、丰花月季 重庆 2700
16 4 4 1 2017-3-19 2017-8-28 侧柏、红枫 北京 2800
17 4 4 2 2017-3-13 2017-8-29 竹柏、侧柏 江苏 2900
18 4 4 3 2017-3-26 2017-8-30 柳杉、竹柏 浙江 3000
19 4 4 4 2017-3-10 2017-8-13 国槐、柳杉 安徽 3100
2 1 1 2 2017-3-15 2017-8-29 梅花、香樟 浙江 1000
20 4 4 5 2017-3-11 2017-8-12 白蜡树、国槐 湖南 3200
21 5 5 1 2017-3-12 2017-8-11 落羽松、雪松 湖北 3300
22 5 5 2 2017-3-13 2017-8-10 雪松、国槐 上海 3400
23 5 5 3 2017-3-9 2017-8-9 罗汉松、白蜡树 河北 3500
24 5 5 4 2017-3-8 2017-8-8 木荷、罗汉松 河南 3500
25 5 5 5 2017-3-7 2017-8-7 樱花、木荷 海南 3000
26 2 2 6 2017-4-8 2017-9-8 连翘、法桐 江苏 10000
3 1 1 3 2017-3-21 2017-8-15 桂花、棕榈 安徽 1500
4 1 1 4 2017-3-20 2017-8-16 红花槐、棕榈 湖南 1600
5 1 1 5 2017-3-18 2017-8-17 桢楠、红花槐 湖北 1700
6 2 2 1 2017-3-17 2017-8-18 池杉、桢楠 上海 1800
7 2 2 2 2017-3-28 2017-8-19 木槿、海滨木槿 河北 1900
8 2 2 3 2017-3-27 2017-8-20 法桐、桢楠 河南 2000
9 2 2 4 2017-3-29 2017-8-21 连翘、法桐 山西 2100
tree表:

1 1 落羽松
2 1 金钱松
3 1 水杉
4 1 池杉
5 1 法桐
yinaoxiao7661 2017-04-07
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引用 7 楼 jinfengyiye 的回复:
order by treename 就是最正常的一种方式。

但是看楼主不是想要这个,你是想要treename的数量来排序?
那你试一下这个
;with cte as (
select * from xxx ,xxx from xxxxxx --你上面个查询
) ,c1 as (
select count(*) as ct ,treename from xxxxx --你下面个查询
)
select * from cte a join c1 b on a.treename=b.treename order by b.ct desc;

对,我是想通过统计查询结果中treename的数量来排序,我看了下你这种查询方式我不太懂,复制粘贴后查询报错
yinaoxiao7661 2017-04-07
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引用 9 楼 baidu_35289351 的回复:
在楼主的基础上;另外,楼主的2个表有相同的字段名称,为了查询结果不出现2个相同字段,建议 tree表的treeId用别名 T_treeId select * from ( select s.supplyId,s.treeType,s.treeId,s.userId,s.releaseTime,s.validPeriod,s.supplyDescribe,s.supplyPlace,s.supplySum, t.treeId as T_treeId,t.treeTypeId as T_treeTypeId,t.treeName from supply s,tree t where s.treeId=t.treeId)a order by T_treeId
查询结果不是通过treeId来排序的,是通过查询结果的treename的数量来排序
baidu_35289351 2017-04-07
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在楼主的基础上;另外,楼主的2个表有相同的字段名称,为了查询结果不出现2个相同字段,建议 tree表的treeId用别名 T_treeId select * from ( select s.supplyId,s.treeType,s.treeId,s.userId,s.releaseTime,s.validPeriod,s.supplyDescribe,s.supplyPlace,s.supplySum, t.treeId as T_treeId,t.treeTypeId as T_treeTypeId,t.treeName from supply s,tree t where s.treeId=t.treeId)a order by T_treeId
二月十六 版主 2017-04-07
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贴点测试数据,我自己建表试试
--高级查询在数据库中用得是最频繁的,也是应用最广泛的。 Ø 基本常用查询 --select select * from student; --all 查询所有 select all sex from student; --distinct 过滤重复 select distinct sex from student; --count 统计 select count(*) from student; select count(sex) from student; select count(distinct sex) from student; --top 取前N条记录 select top 3 * from student; --alias column name 列重命名 select id as 编号, name '名称', sex 性别 from student; --alias table name 表重命名 select id, name, s.id, s.name from student s; --column 列运算 select (age + id) col from student; select s.name + '-' + c.name from classes c, student s where s.cid = c.id; --where 条件 select * from student where id = 2; select * from student where id > 7; select * from student where id < 3; select * from student where id <> 3; select * from student where id >= 3; select * from student where id <= 5; select * from student where id !> 3; select * from student where id !< 5; --and 并且 select * from student where id > 2 and sex = 1; --or 或者 select * from student where id = 2 or sex = 1; --between ... and ... 相当于并且 select * from student where id between 2 and 5; select * from student where id not between 2 and 5; --like 模糊查询 select * from student where name like '%a%'; select * from student where name like '%[a][o]%'; select * from student where name not like '%a%'; select * from student where name like 'ja%'; select * from student where name not like '%[j,n]%'; select * from student where name like '%[j,n,a]%'; select * from student where name like '%[^ja,as,on]%'; select * from student where name like '%[ja_on]%'; --in 子查询 select * from student where id in (1, 2); --not in 不在其中 select * from student where id not in (1, 2); --is null 是空 select * from student where age is null; --is not null 不为空 select * from student where age is not null; --order by 排序 select * from student order by name; select * from student order by name desc; select * from student order by name asc; --group by 分组 按照年龄进行分组统计 select count(age), age from student group by age; 按照性别进行分组统计 select count(*), sex from student group by sex; 按照年龄和性别组合分组统计,并排序 select count(*), sex from student group by sex, age order by age; 按照性别分组,并且是id大于2的记录最后按照性别排序 select count(*), sex from student where id > 2 group by sex order by sex; 查询id大于2的数据,并完成运算后的结果进行分组和排序 select count(*), (sex * id) new from student where id > 2 group by sex * id order by sex * id; --group by all 所有分组 按照年龄分组,是所有的年龄 select count(*), age from student group by all age; --having 分组过滤条件 按照年龄分组,过滤年龄为空的数据,并且统计分组的条数和现实年龄信息 select count(*), age from student group by age having age is not null; 按照年龄和cid组合分组,过滤条件是cid大于1的记录 select count(*), cid, sex from student group by cid, sex having cid > 1; 按照年龄分组,过滤条件是分组后的记录条数大于等于2 select count(*), age from student group by age having count(age) >= 2; 按照cid和性别组合分组,过滤条件是cid大于1,cid的最大值大于2 select count(*), cid, sex from student group by cid, sex having cid > 1 and max(cid) > 2; Ø 嵌套子查询 子查询是一个嵌套在select、insert、update或delete语句或其他子查询中的查询。任何允许使用表达式的地方都可以使用子查询子查询也称为内部查询或内部选择,而包含子查询的语句也成为外部查询或外部选择。 # from (select … table)示例 将一个table的查询结果当做一个新表进行查询 select * from ( select id, name from student where sex = 1 ) t where t.id > 2; 上面括号中的语句,就是子查询语句(内部查询)。在外面的是外部查询,其中外部查询可以包含以下语句: 1、 包含常规选择列表组件的常规select查询 2、 包含一个或多个表或视图名称的常规from语句 3、 可选的where子句 4、 可选的group by子句 5、 可选的having子句 # 示例 查询班级信息,统计班级学生人生 select *, (select count(*) from student where cid = classes.id) as num from classes order by num; # in, not in子句查询示例 查询班级id大于小于的这些班级的学生信息 select * from student where cid in ( select id from classes where id > 2 and id < 4 ); 查询不是班的学生信息 select * from student where cid not in ( select id from classes where name = '2班' ) in、not in 后面的子句返回的结果必须是一列,这一列的结果将会作为查询条件对应前面的条件。如cid对应子句的id; # exists和not exists子句查询示例 查询存在班级id为的学生信息 select * from student where exists ( select * from classes where id = student.cid and id = 3 ); 查询没有分配班级的学生信息 select * from student where not exists ( select * from classes where id = student.cid ); exists和not exists查询需要内部查询和外部查询进行一个关联的条件,如果没有这个条件将是查询到的所有信息。如:id等于student.id; # some、any、all子句查询示例 查询班级的学生年龄大于班级的学生的年龄的信息 select * from student where cid = 5 and age > all ( select age from student where cid = 3 ); select * from student where cid = 5 and age > any ( select age from student where cid = 3 ); select * from student where cid = 5 and age > some ( select age from student where cid = 3 ); Ø 聚合查询 1、 distinct去掉重复数据 select distinct sex from student; select count(sex), count(distinct sex) from student; 2、 compute和compute by汇总查询 对年龄大于的进行汇总 select age from student where age > 20 order by age compute sum(age) by age; 对年龄大于的按照性别进行分组汇总年龄信息 select id, sex, age from student where age > 20 order by sex, age compute sum(age) by sex; 按照年龄分组汇总 select age from student where age > 20 order by age, id compute sum(age); 按照年龄分组,年龄汇总,id找最大值 select id, age from student where age > 20 order by age compute sum(age), max(id); compute进行汇总前面是查询的结果,后面一条结果集就是汇总的信息。compute子句中可以添加多个汇总表达式,可以添加的信息如下: a、 可选by关键字。它是每一列计算指定的行聚合 b、 行聚合函数名称。包括sum、avg、min、max、count等 c、 要对其执行聚合函数的列 compute by适合做先分组后汇总的业务。compute by后面的列一定要是order by中出现的列。 3、 cube汇总 cube汇总和compute效果类似,但语法较简洁,而且返回的是一个结果集。 select count(*), sex from student group by sex with cube; select count(*), age, sum(age) from student where age is not null group by age with cube; cube要结合group by语句完成分组汇总 Ø 排序函数 排序在很多地方需要用到,需要对查询结果进行排序并且给出序号。比如: 1、 对某张表进行排序,序号需要递增不重复的 2、 对学生的成绩进行排序,得出名次,名次可以并列,但名次的序号是连续递增的 3、 在某些排序的情况下,需要跳空序号,虽然是并列 基本语法 排序函数 over([分组语句] 排序子句[desc][asc]) 排序子句 order by 列名, 列名 分组子句 partition by 分组列, 分组列 # row_number函数 根据排序子句给出递增连续序号 按照名称排序的顺序递增 select s.id, s.name, cid, c.name, row_number() over(order by c.name) as number from student s, classes c where cid = c.id; # rank函数函数 根据排序子句给出递增的序号,但是存在并列并且跳空 顺序递增 select id, name, rank() over(order by cid) as rank from student; 跳过相同递增 select s.id, s.name, cid, c.name, rank() over(order by c.name) as rank from student s, classes c where cid = c.id; # dense_rank函数 根据排序子句给出递增的序号,但是存在并列不跳空 不跳过,直接递增 select s.id, s.name, cid, c.name, dense_rank() over(order by c.name) as dense from student s, classes c where cid = c.id; # partition by分组子句 可以完成对分组的数据进行增加排序,partition by可以与以上三个函数联合使用。 利用partition by按照班级名称分组,学生id排序 select s.id, s.name, cid, c.name, row_number() over(partition by c.name order by s.id) as rank from student s, classes c where cid = c.id; select s.id, s.name, cid, c.name, rank() over(partition by c.name order by s.id) as rank from student s, classes c where cid = c.id; select s.id, s.name, cid, c.name, dense_rank() over(partition by c.name order by s.id) as rank from student s, classes c where cid = c.id; # ntile平均排序函数 将要排序的数据进行平分,然后按照等分排序。ntile中的参数代表分成多少等分。 select s.id, s.name, cid, c.name, ntile(5) over(order by c.name) as ntile from student s, classes c where cid = c.id; Ø 集合运算 操作两组查询结果,进行交集、并集、减集运算 1、 union和union all进行并集运算 --union 并集、不重复 select id, name from student where name like 'ja%' union select id, name from student where id = 4; --并集、重复 select * from student where name like 'ja%' union all select * from student; 2、 intersect进行交集运算 --交集(相同部分) select * from student where name like 'ja%' intersect select * from student; 3、 except进行减集运算 --减集(除相同部分) select * from student where name like 'ja%' except select * from student where name like 'jas%'; Ø 公式表表达式 查询表的时候,有时候中间表需要重复使用,这些子查询被重复查询调用,不但效率低,而且可读性低,不利于理解。那么公式表表达式可以解决这个问题。 我们可以将公式表表达式(CET)视为临时结果集,在select、insert、update、delete或是create view语句的执行范围内进行定义。 --表达式 with statNum(id, num) as ( select cid, count(*) from student where id > 0 group by cid ) select id, num from statNum order by id; with statNum(id, num) as ( select cid, count(*) from student where id > 0 group by cid ) select max(id), avg(num) from statNum; Ø 连接查询 1、 简化连接查询 --简化联接查询 select s.id, s.name, c.id, c.name from student s, classes c where s.cid = c.id; 2、 left join左连接 --左连接 select s.id, s.name, c.id, c.name from student s left join classes c on s.cid = c.id; 3、 right join右连接 --右连接 select s.id, s.name, c.id, c.name from student s right join classes c on s.cid = c.id; 4、 inner join内连接 --内连接 select s.id, s.name, c.id, c.name from student s inner join classes c on s.cid = c.id; --inner可以省略 select s.id, s.name, c.id, c.name from student s join classes c on s.cid = c.id; 5、 cross join交叉连接 --交叉联接查询,结果是一个笛卡儿乘积 select s.id, s.name, c.id, c.name from student s cross join classes c --where s.cid = c.id; 6、 自连接(同一张表进行连接查询) --自连接 select distinct s.* from student s, student s1 where s.id <> s1.id and s.sex = s1.sex; Ø 函数 1、 聚合函数 max最大值、min最小值、count统计、avg平均值、sum求和、var求方差 select max(age) max_age, min(age) min_age, count(age) count_age, avg(age) avg_age, sum(age) sum_age, var(age) var_age from student; 2、 日期时间函数 select dateAdd(day, 3, getDate());--加天 select dateAdd(year, 3, getDate());--加年 select dateAdd(hour, 3, getDate());--加小时 --返回跨两个指定日期的日期边界数和时间边界数 select dateDiff(day, '2011-06-20', getDate()); --相差秒数 select dateDiff(second, '2011-06-22 11:00:00', getDate()); --相差小时数 select dateDiff(hour, '2011-06-22 10:00:00', getDate()); select dateName(month, getDate());--当前月份 select dateName(minute, getDate());--当前分钟 select dateName(weekday, getDate());--当前星期 select datePart(month, getDate());--当前月份 select datePart(weekday, getDate());--当前星期 select datePart(second, getDate());--当前秒数 select day(getDate());--返回当前日期天数 select day('2011-06-30');--返回当前日期天数 select month(getDate());--返回当前日期月份 select month('2011-11-10'); select year(getDate());--返回当前日期年份 select year('2010-11-10'); select getDate();--当前系统日期 select getUTCDate();--utc日期 3、 数学函数 select pi();--PI函数 select rand(100), rand(50), rand(), rand();--随机数 select round(rand(), 3), round(rand(100), 5);--精确小数位 --精确位数,负数表示小数点前 select round(123.456, 2), round(254.124, -2); select round(123.4567, 1, 2);

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