SQL行轉列、列轉行java
這個主題仍是比較常見的,行轉列主要適用於對數據做聚合統計,如統計某類目的商品在某個時間區間的銷售狀況。列轉行問題一樣也很常見。mysql
1、整理測試數據sql
create table wyc_test( id int(32) not null auto_increment, name varchar(80) default null, date date default null, scount int(32), primary key (id) ); INSERT INTO `wyc_test` (`id`,`name`,`date`,`scount`) VALUES (1,'小說','2013-09-01',10000); INSERT INTO `wyc_test` (`id`,`name`,`date`,`scount`) VALUES (2,'微信','2013-09-01',20000); INSERT INTO `wyc_test` (`id`,`name`,`date`,`scount`) VALUES (3,'小說','2013-09-02',30000); INSERT INTO `wyc_test` (`id`,`name`,`date`,`scount`) VALUES (4,'微信','2013-09-02',35000); INSERT INTO `wyc_test` (`id`,`name`,`date`,`scount`) VALUES (5,'小說','2013-09-03',31000); INSERT INTO `wyc_test` (`id`,`name`,`date`,`scount`) VALUES (6,'微信','2013-09-03',36000); INSERT INTO `wyc_test` (`id`,`name`,`date`,`scount`) VALUES (7,'小說','2013-09-04',35000); INSERT INTO `wyc_test` (`id`,`name`,`date`,`scount`) VALUES (8,'微信','2013-09-04',38000); INSERT INTO `wyc_test` (`id`,`name`,`date`,`scount`) VALUES (9,'小說','2013-09-01',80000); INSERT INTO `wyc_test` (`id`,`name`,`date`,`scount`) VALUES (10,'微信','2013-09-01',70000);
2、行轉列微信
主要思路是分組後使用case進行條件判斷處理函數
#行轉列 select a.date, sum(case a.name when '小說' then a.scount else 0 end) 'sum_小說', max(case a.name when '小說' then a.scount else 0 end) 'max_小說', sum(case a.name when '微信' then a.scount else 0 end) '微信', max(case a.name when '小說' then a.scount else 0 end) 'max_微信' from wyc_test a group by date;
結果:測試
3、列轉行code
主要思路也是分組後使用caseblog
#列轉行 select a.date, concat('小說:', cast(sum(case a.name when '小說' then a.scount else 0 end) as char), '微信', cast(sum(case a.name when '微信' then a.scount else 0 end) as char)) as 'str' from wyc_test a group by a.date; #列轉行 #1.使用mysql提供的函數分組 select a.date,group_concat(a.name,'總量:', a.scount) from wyc_test a group by a.date,a.name; #2.使用mysql提供的函數分組 select a.date,a.name, group_concat(a.name, '總量:', a.scount) from wyc_test a group by a.date,a.name; #3.普通group結合字符串拼接 SELECT a.date, concat('小說總量:', cast(sum(case a.name when '小說' then a.scount else 0 end) as char)) as '小說', concat('微信總量:', cast(sum(case a.name when '微信' then a.scount else 0 end) as char)) as '微信' from wyc_test a group by a.date;
結果:
rem
4、列轉行詳解
1.一、初始測試數據
表結構:TEST_TB_GRADE2
Sql代碼
create table TEST_TB_GRADE2
(
ID NUMBER(10) not null,
USER_NAME VARCHAR2(20 CHAR),
CN_SCORE FLOAT,
MATH_SCORE FLOAT,
EN_SCORE FLOAT
)
初始數據以下圖:字符串
1.二、 若是須要實現以下的查詢效果圖:
這就是最多見的列轉行,主要原理是利用SQL裏面的union,具體的sql語句以下:
Sql代碼
select user_name, '語文' COURSE , CN_SCORE as SCORE from test_tb_grade2
union select user_name, '數學' COURSE, MATH_SCORE as SCORE from test_tb_grade2
union select user_name, '英語' COURSE, EN_SCORE as SCORE from test_tb_grade2
order by user_name,COURSE
也能夠利用【 insert all into ... select 】來實現,首先須要先建一個表TEST_TB_GRADE3:
Sql代碼
create table TEST_TB_GRADE3
(
USER_NAME VARCHAR2(20 CHAR),
COURSE VARCHAR2(20 CHAR),
SCORE FLOAT
)
再執行下面的sql:
Sql代碼
insert all
into test_tb_grade3(USER_NAME,COURSE,SCORE) values(user_name, '語文', CN_SCORE)
into test_tb_grade3(USER_NAME,COURSE,SCORE) values(user_name, '數學', MATH_SCORE)
into test_tb_grade3(USER_NAME,COURSE,SCORE) values(user_name, '英語', EN_SCORE)
select user_name, CN_SCORE, MATH_SCORE, EN_SCORE from test_tb_grade2;
commit;
別忘記commit操做,而後再查詢TEST_TB_GRADE3,發現表中的數據就是列轉成行了。