Day1_HTML_框架集标签

多集分组

select a,b,count(*) from tab1,tab2
group by
 grouping sets(a,(a,b))
 having grouping(a)=1
 
Tip:
grouping(a)值为1时,代表统计的是a列,以除a以外的列分组
 
例1:
select a,b,count(*) as sum from tab1 group by a grouping sets(a,b);
=
select a,count(*) as sum from tab1 group by a ;
+
select b,count(*) as sum from tab1 group by b ;
 
例2:
 
--()增加总计
select a, b,count(*) from tbname group by grouping sets(a,(a,b),());
=
 select count(*) from tbname;
+
 select a,count(*) from tbname group by a;
+
 select a,b,count(*) from tbname group by a,b
 
 

增加总计

select value(char(a),'all'),
         value(char(b),'all b '),
count(*)
from tab1,tab2
where tab1.n=tab2.n
group by (char(a),(char(a),b),()); 
 
Tip:
value(a,b) 当a为空值时,返回b的值.用法与COALESCE相当,注意a与b的类型必须相同

rollup

group by rollup(a,b,c) order by a,b,c 
 
 
rollup(a,b,c)=group by(a,b,c)+group by(a,b)+group by (a)+group by(全部)
 

cube

group by cube(a,b,c) order by a,b,c
group by a,b,c with cube
 
cube(a,b,c)=group by(a,b,c)+group by(a,b)+group by(a,c)+group by(a)+group by(b,c)+group by(b)+group by(c)+group by(全部)
 

美化合计结果

select Decode(Grouping(a),1,'a统计',a) ,Decode(Grouping(b),1,'b统计',b) ,count(*) from tbname group by grouping sets(a,b)
 
Tip:
decode(条件,值1,翻译值1,值2,翻译值2,...值n,翻译值n,缺省值)
该函数的含义如下：
IF 条件=值1 THEN
　　　　RETURN(翻译值1)
ELSIF 条件=值2 THEN
　　　　RETURN(翻译值2)
　　　　......
ELSIF 条件=值n THEN
　　　　RETURN(翻译值n)
ELSE
　　　　RETURN(缺省值)
END IF