PostgreSQL 實現列轉行問題
阿新 • • 發佈：2021-01-12
1 測試表資料
SELECT relative_label_content FROM frk_s.label_cor_gene relative_label_content ------ AA BB CC
2 列轉行寫法
寫法1：
string_agg
SELECT frwybs,string_agg (relative_label_content,',') as relative_label_content FROM frk_s.label_cor_gene GROUP BY frwybs relative_label_content ------------ AA,BB,CC
寫法2：
array_to_string(ARRAY_AGG (text),')
SELECT
frwybs,array_to_string(
ARRAY_AGG (DISTINCT relative_label_content),'
) as labels_content
FROM
frk_s.label_cor_gene
GROUP BY
frwybs
labels_content
------------
AA,CC
補充：PostgreSQL行列轉換(相容oracle pivot unpivot)
oracle11g開始內建了資料透視表pivot table這一功能，可以用來實現行列轉換的功能，但是在資料量較大的時候使用效能就會較差。
pivot語法為：
SELECT ... FROM ... PIVOT [XML] (pivot_clause pivot_for_clause pivot_in_clause ) WHERE ...
oracle pivot使用例子：
–建立測試表並插入資料
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',23,21,'math');
insert into usr values('c','phy');
insert into usr values('c',24,'math');
insert into usr values('d',25,'phy');
–使用pivot進行行列轉換
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
我們還可以使用unpivot來實現列轉行。
unpivot語法為：
SELECT ... FROM ... UNPIVOT [INCLUDE|EXCLUDE NULLS] (unpivot_clause unpivot_for_clause unpivot_in_clause ) WHERE ...
oracle unpivot使用例子：
–建立測試表並插入資料
CREATE TABLE t1 ( VendorID int,Emp1 int,Emp2 int,Emp3 int,Emp4 int,Emp5 int ); INSERT INTO t1 VALUES (1,4,3,5,4); INSERT INTO t1 VALUES (2,1,5); INSERT INTO t1 VALUES (3,4); INSERT INTO t1 VALUES (4,2,4); INSERT INTO t1 VALUES (5,5);
–使用unpivot進行列轉行
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.
那麼在pg中該如何實現oracle的pivot/unpivot的行列轉行功能呢？pg中自帶的tablefunc外掛可以實現，我們可以使用該外掛中的crosstab函式介面進行行列轉換。
pg行轉列例子：
–建表插入測試資料
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',02,234567);
insert into tbl values ('test1',03,345678);
insert into tbl values ('test1',04,05,567890);
insert into tbl values ('test2',12);
insert into tbl values ('test2',23);
insert into tbl values ('test2',34);
insert into tbl values ('test2',45);
insert into tbl values ('test2',56);
insert into tbl values ('test3',12);
insert into tbl values ('test3',45);
insert into tbl values ('test3',56);
insert into tbl values ('test4',20);
insert into tbl values ('test4',30);
insert into tbl values ('test4',40);
insert into tbl values ('test4',50);
insert into tbl values ('test1',2019,567890);
insert into tbl values ('test1',06,07,08,09,10,11,12,234567);
insert into tbl values ('test2',23);
insert into tbl select * from tbl;
–行轉列
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(# -- 這個是需要進行行列變換的源SQL ， 資料來源。
bill(# -- 排序欄位為group by欄位 ，最後一個欄位為轉換後的內容欄位，導數第二個欄位為行列變換的欄位（內容為列舉，比如月份）
bill(# -- （必須在下一個引數中提取出對應的所有列舉值）
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(# -- 行列轉換的行，有哪些值被提取出來作為列。 這個在這裡代表的是月份，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 輸出格式
bill-# ( js jsonb,-- 第一個引數SQL內對應的order by對應的欄位（1個或多個）
bill(# Jan numeric,-- 第一個引數SQL內對應導數第二個欄位的列舉值，（行轉列）
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)
–列轉行
bill=# with a as ( -- A對應原始資料（即需要列轉行的資料）
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(# -- 這個是需要進行行列變換的源SQL ， 資料來源。
bill(# -- 排序欄位為group by欄位 ，最後一個欄位為轉換後的內容欄位，導數第二個欄位為行列變換的欄位（內容為列舉，比如月份）
bill(# -- （必須在下一個引數中提取出對應的所有列舉值）
bill(# $$select jsonb_build_object('seller',...('dec')) t(se_month))
bill(# 'select distinct se_month from tbl order by 1'
bill(# )
bill(# as -- crosstab 輸出格式
bill(# ( js jsonb,bill(# dec numeric
bill(# )
bill(# order by 1,2
bill(# )
bill-#,bill-# -- b ， 用jsonb把多列合併為一列，並使用jsonb_each展開。
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,(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)
以上為個人經驗，希望能給大家一個參考，也希望大家多多支援我們。如有錯誤或未考慮完全的地方，望不吝賜教。