oracle11g开始内置了数据透视表pivot table这一功能，可以用来实现行列转换的功能，但是在数据量较大的时候使用性能就会较差。
pivot语法为：
SELECT ...
FROM ...
PIVOT [XML]
(pivot_clause
pivot_for_clause
pivot_in_clause )
WHERE ...
oracle pivot使用例子：
–创建测试表并插入数据
create table usr
(name varchar2(20),
score int,
class varchar2(20)
);
insert into usr values('a',20,'math');
insert into usr values('a',22,'phy');
insert into usr values('b',23,'phy');
insert into usr values('b',21,'math');
insert into usr values('c',22,'phy');
insert into usr values('c',24,'math');
insert into usr values('d',25,'math');
insert into usr values('d',23,'phy');
–使用pivot进行行列转换
SQL> select * from usr
2 pivot(
sum(score)
for class in ('math','phy')
3 4 5 );
NAME 'math' 'phy'
-------------------- ---------- ----------
d 25 23
a 20 22
b 21 23
c 24 22
我们还可以使用unpivot来实现列转行。
unpivot语法为：
SELECT ...
FROM ...
UNPIVOT [INCLUDE|EXCLUDE NULLS]
(unpivot_clause
unpivot_for_clause
unpivot_in_clause )
WHERE ...
oracle unpivot使用例子：
–创建测试表并插入数据
CREATE TABLE t1
(
VendorID int,
Emp1 int,
Emp2 int,
Emp3 int,
Emp4 int,
Emp5 int
);
INSERT INTO t1 VALUES (1,4,3,5,4,4);
INSERT INTO t1 VALUES (2,4,1,5,5,5);
INSERT INTO t1 VALUES (3,4,3,5,4,4);
INSERT INTO t1 VALUES (4,4,2,5,5,4);
INSERT INTO t1 VALUES (5,5,1,5,5,5);
–使用unpivot进行列转行
SQL> select * from t1
2 UNPIVOT(
orders for Employee in(emp1,emp2,emp3,emp4,emp5)
); 3 4
VENDORID EMPL ORDERS
---------- ---- ----------
1 EMP1 4
1 EMP2 3
1 EMP3 5
1 EMP4 4
1 EMP5 4
2 EMP1 4
2 EMP2 1
2 EMP3 5
2 EMP4 5
2 EMP5 5
3 EMP1 4
VENDORID EMPL ORDERS
---------- ---- ----------
3 EMP2 3
3 EMP3 5
3 EMP4 4
3 EMP5 4
4 EMP1 4
4 EMP2 2
4 EMP3 5
4 EMP4 5
4 EMP5 4
5 EMP1 5
5 EMP2 1
VENDORID EMPL ORDERS
---------- ---- ----------
5 EMP3 5
5 EMP4 5
5 EMP5 5
25 rows selected.
那么在pg中该如何实现oracle的pivot/unpivot的行列转行功能呢？pg中自带的tablefunc插件可以实现，我们可以使用该插件中的crosstab函数接口进行行列转换。
pg行转列例子：
–建表插入测试数据
create table tbl (seller text,se_year int,se_month int,se_amount int);
insert into tbl values ('test1',2020,01,123456);
insert into tbl values ('test1',2020,02,234567);
insert into tbl values ('test1',2020,03,345678);
insert into tbl values ('test1',2020,04,345678);
insert into tbl values ('test1',2020,05,567890);
insert into tbl values ('test2',2020,01,12);
insert into tbl values ('test2',2020,02,23);
insert into tbl values ('test2',2020,03,34);
insert into tbl values ('test2',2020,04,45);
insert into tbl values ('test2',2020,05,56);
insert into tbl values ('test3',2020,03,12);
insert into tbl values ('test3',2020,04,45);
insert into tbl values ('test3',2020,05,56);
insert into tbl values ('test4',2020,02,20);
insert into tbl values ('test4',2020,03,30);
insert into tbl values ('test4',2020,04,40);
insert into tbl values ('test4',2020,05,50);
insert into tbl values ('test1',2019,01,123456);
insert into tbl values ('test1',2019,02,234567);
insert into tbl values ('test1',2019,03,345678);
insert into tbl values ('test1',2019,04,345678);
insert into tbl values ('test1',2019,05,567890);
insert into tbl values ('test1',2019,06,123456);
insert into tbl values ('test1',2019,07,234567);
insert into tbl values ('test1',2019,08,345678);
insert into tbl values ('test1',2019,09,345678);
insert into tbl values ('test1',2019,10,567890);
insert into tbl values ('test1',2019,11,123456);
insert into tbl values ('test1',2019,12,234567);
insert into tbl values ('test2',2019,11,12);
insert into tbl values ('test2',2019,12,23);
insert into tbl select * from tbl;
–行转列
bill=# select
bill-# js->>'seller' as seller,
bill-# js->>'se_year' as se_year,
bill-# jan ,
bill-# feb ,
bill-# mar ,
bill-# apr ,
bill-# may ,
bill-# jun ,
bill-# jul ,
bill-# aug ,
bill-# sep ,
bill-# oct ,
bill-# nov ,
bill-# dec
bill-# from crosstab(
bill(# -- 这个是需要进行行列变换的源SQL ， 数据源。
bill(# -- 排序字段为group by字段 ，最后一个字段为转换后的内容字段，导数第二个字段为行列变换的字段（内容为枚举，比如月份）
bill(# -- （必须在下一个参数中提取出对应的所有枚举值）
bill(# $$select jsonb_build_object('seller', seller, 'se_year', se_year) as js, se_month, sum(se_amount) from tbl group by 1,2 order by 1$$,
bill(# -- 行列转换的行，有哪些值被提取出来作为列。 这个在这里代表的是月份，也就是se_month的值
bill(# -- 或(select * from (values('jan'),...('dec')) t(se_month))
bill(# 'select distinct se_month from tbl order by 1'
bill(# )
bill-# as -- crosstab 输出格式
bill-# ( js jsonb, -- 第一个参数SQL内对应的order by对应的字段（1个或多个）
bill(# Jan numeric, -- 第一个参数SQL内对应导数第二个字段的枚举值，（行转列）
bill(# feb numeric, -- ...同上
bill(# mar numeric,
bill(# apr numeric,
bill(# may numeric,
bill(# jun numeric,
bill(# jul numeric,
bill(# aug numeric,
bill(# sep numeric,
bill(# oct numeric,
bill(# nov numeric,
bill(# dec numeric
bill(# )
bill-# order by 1,2;
seller | se_year | jan | feb | mar | apr | may | jun | jul | aug | sep | oct | nov | dec
--------+---------+--------+--------+--------+--------+---------+--------+--------+--------+--------+---------+--------+--------
test1 | 2019 | 246912 | 469134 | 691356 | 691356 | 1135780 | 246912 | 469134 | 691356 | 691356 | 1135780 | 246912 | 469134
test1 | 2020 | 246912 | 469134 | 691356 | 691356 | 1135780 | | | | | | |
test2 | 2019 | | | | | | | | | | | 24 | 46
test2 | 2020 | 24 | 46 | 68 | 90 | 112 | | | | | | |
test3 | 2020 | | | 24 | 90 | 112 | | | | | | |
test4 | 2020 | | 40 | 60 | 80 | 100 | | | | | | |
(6 rows)
–列转行
bill=# with a as ( -- A对应原始数据（即需要列转行的数据）
bill(# select
bill(# js->>'seller' as seller,
bill(# js->>'se_year' as se_year,
bill(# jan ,
bill(# feb ,
bill(# mar ,
bill(# apr ,
bill(# may ,
bill(# jun ,
bill(# jul ,
bill(# aug ,
bill(# sep ,
bill(# oct ,
bill(# nov ,
bill(# dec
bill(# from crosstab(
bill(# -- 这个是需要进行行列变换的源SQL ， 数据源。
bill(# -- 排序字段为group by字段 ，最后一个字段为转换后的内容字段，导数第二个字段为行列变换的字段（内容为枚举，比如月份）
bill(# -- （必须在下一个参数中提取出对应的所有枚举值）
bill(# $$select jsonb_build_object('seller', seller, 'se_year', se_year) as js, se_month, sum(se_amount) from tbl group by 1,2 order by 1$$,
bill(# -- 行列转换的行，有哪些值被提取出来作为列。 这个在这里代表的是月份，也就是se_month的值
bill(# -- 或(select * from (values('jan'),...('dec')) t(se_month))
bill(# 'select distinct se_month from tbl order by 1'
bill(# )
bill(# as -- crosstab 输出格式
bill(# ( js jsonb, -- 第一个参数SQL内对应的order by对应的字段（1个或多个）
bill(# Jan numeric, -- 第一个参数SQL内对应导数第二个字段的枚举值，（行转列）
bill(# feb numeric, -- ...同上
bill(# mar numeric,
bill(# apr numeric,
bill(# may numeric,
bill(# jun numeric,
bill(# jul numeric,
bill(# aug numeric,
bill(# sep numeric,
bill(# oct numeric,
bill(# nov numeric,
bill(# dec numeric
bill(# )
bill(# order by 1,2
bill(# )
bill-# ,
bill-# -- b ， 用jsonb把多列合并为一列，并使用jsonb_each展开。
bill-# b as (select seller, se_year, jsonb_each(row_to_json(a)::jsonb-'seller'::text-'se_year'::text) as rec from a)
bill-# select seller, se_year, (b.rec).key as month, (b.rec).value as sum from b;
seller | se_year | month | sum
--------+---------+-------+---------
test1 | 2019 | apr | 691356
test1 | 2019 | aug | 691356
test1 | 2019 | dec | 469134
test1 | 2019 | feb | 469134
test1 | 2019 | jan | 246912
test1 | 2019 | jul | 469134
test1 | 2019 | jun | 246912
test1 | 2019 | mar | 691356
test1 | 2019 | may | 1135780
test1 | 2019 | nov | 246912
test1 | 2019 | oct | 1135780
test1 | 2019 | sep | 691356
test1 | 2020 | apr | 691356
test1 | 2020 | aug | null
test1 | 2020 | dec | null
test1 | 2020 | feb | 469134
test1 | 2020 | jan | 246912
test1 | 2020 | jul | null
test1 | 2020 | jun | null
test1 | 2020 | mar | 691356
test1 | 2020 | may | 1135780
test1 | 2020 | nov | null
test1 | 2020 | oct | null
test1 | 2020 | sep | null
test2 | 2019 | apr | null
test2 | 2019 | aug | null
test2 | 2019 | dec | 46
test2 | 2019 | feb | null
test2 | 2019 | jan | null
test2 | 2019 | jul | null
test2 | 2019 | jun | null
test2 | 2019 | mar | null
test2 | 2019 | may | null
test2 | 2019 | nov | 24
test2 | 2019 | oct | null
test2 | 2019 | sep | null
test2 | 2020 | apr | 90
test2 | 2020 | aug | null
test2 | 2020 | dec | null
test2 | 2020 | feb | 46
test2 | 2020 | jan | 24
test2 | 2020 | jul | null
test2 | 2020 | jun | null
test2 | 2020 | mar | 68
test2 | 2020 | may | 112
test2 | 2020 | nov | null
test2 | 2020 | oct | null
test2 | 2020 | sep | null
test3 | 2020 | apr | 90
test3 | 2020 | aug | null
test3 | 2020 | dec | null
test3 | 2020 | feb | null
test3 | 2020 | jan | null
test3 | 2020 | jul | null
test3 | 2020 | jun | null
test3 | 2020 | mar | 24
test3 | 2020 | may | 112
test3 | 2020 | nov | null
test3 | 2020 | oct | null
test3 | 2020 | sep | null
test4 | 2020 | apr | 80
test4 | 2020 | aug | null
test4 | 2020 | dec | null
test4 | 2020 | feb | 40
test4 | 2020 | jan | null
test4 | 2020 | jul | null
test4 | 2020 | jun | null
test4 | 2020 | mar | 60
test4 | 2020 | may | 100
test4 | 2020 | nov | null
test4 | 2020 | oct | null
test4 | 2020 | sep | null
(72 rows)
