写了一个MYSQL的行转列的存储过程。-白红宇

网上的都是一些静态的，用CASE WHEN结构实现。所以我写了一个动态的。

SP 代码：

DELIMITER $$
DROP PROCEDURE IF EXISTS `test`.`sp_row_column_wrap`$$
CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_row_column_wrap`(IN $schema_name varchar(64),
IN $table_name varchar(64))
 BEGIN
   declare cnt int(11);
   declare $table_rows int(11);
   declare i int(11);
   declare j int(11);
   declare s int(11);
   declare str varchar(255);
  -- Get the column number of the table
   select count(1) from information_schema.columns where table_schema=$schema_name and table_name=$table_name into cnt;
   -- Get the row number of the table
   select table_rows from information_schema.tables where table_schema = $schema_name and table_name=$table_name into $table_rows;
   -- Check whether the table exists or not
   drop table if exists test.temp;
   create table if not exists test.temp (`1` varchar(255) not null);
  -- loop1 start
   set i = 0;
   loop1:loop
     if i = $table_rows-1 then
       leave loop1;
     end if;
     set @stmt1 = concat('alter table test.temp add `',i+2,'` varchar(255) not null');
     prepare s1 from @stmt1;
     execute s1;
     deallocate prepare s1;
     set @stmt1 = '';    set i = i + 1;
   end loop loop1;
  -- loop1 end;
   set s = 0;
   -- loop2 start
   loop2:loop
  -- leave loop2
     if s=cnt then
       leave loop2;
     end if;
     set @stmt2 = concat('select column_name from information_schema.columns where table_schema="',$schema_name,
                         '" and table_name="',$table_name,'" limit ',s,',1 into @temp;');
     prepare s2 from @stmt2;
     execute s2;
     deallocate prepare s2;

set @stmt2 = '';

    set j=0;
     set str = ' select ';
     -- Loop3 start
     loop3:loop 
       if j = $table_rows then
         leave loop3;
       end if;
       set @stmt3 = concat('select ',@temp,' from ',$schema_name,'.',$table_name,' limit ',j,',1 into @temp2;');
       prepare s3 from @stmt3;
       execute s3;
       set str = concat(str,'"',@temp2,'"',',');
       deallocate prepare s3;
       set @stmt3 = '';      set j = j+1;
     end loop loop3;
     set str = left(str,length(str)-1);
     -- insert new data into table
     set @stmt4 = concat('insert into test.temp',str,';');
     prepare s4 from @stmt4;
     execute s4;
     deallocate prepare s4;
     set @stmt4 = '';    set s=s+1;
   end loop loop2;
END$$
 DELIMITER ;

以下是测试结果：

======

select * from a;

select * from b;

select * from salary;

call sp_row_column_wrap('test','a');

select * from test.temp;

call sp_row_column_wrap('test','b');

select * from test.temp;

call sp_row_column_wrap('test','salary');

select * from test.temp;

query result(2 records)

aid	title
1	111
2	222

query result(3 records)

bid	aid	image	time
1	2	1.gif	2007-08-08
2	2	2.gif	2007-08-09
3	2	3.gif	2007-08-08

query result(7 records)

id	cost	des	Autoid
1	10	aaaa	1
1	15	bbbb	2
1	20	cccc	3
2	80	aaaa	4
2	100	bbbb	5
2	60	dddd	6
3	500	dddd	7

query result(2 records)

1	2
1	2
111	222

query result(4 records)

1	2	3
1	2	3
2	2	2
1.gif	2.gif	3.gif
2007-08-08	2007-08-09	2007-08-08

query result(4 records)

1	2	3	4	5	6	7
1	1	1	2	2	2	3
10	15	20	80	100	60	500
aaaa	bbbb	cccc	aaaa	bbbb	dddd	dddd
1	2	3	4	5	6	7

本文转自 david_yeung 51CTO博客，原文链接：http://blog.51cto.com/yueliangdao0608/81259，如需转载请自行联系原作者