例1：

思路：

1.建表并插入数据

CREATE table score(name varchar(11),Math int,English int);insert into score (name,Math,English) values (\'甲\',89,78)insert into score values (\'乙\',77,81)insert into score values (\'丙\',87,98)

2.中间转换，即二维转一维得到一维表

3.利用IF判断并分组即可得到转换的表

selectc2 as \'课程\',sum(if(c1=\'甲\',c3,0)) as \'甲\',sum(if(c1=\'乙\',c3,0)) as \'乙\',sum(if(c1=\'丙\',c3,0)) as \'丙\'from((select name as c1,\'Math\' as c2,Math as c3 from score )union(select name,\'English\' as c2,English from score) )as txgroup by c2

例2：

创建表并添加数据

create table usera(userid int,Type int,Duration_sum int)alter table usera modify Duration_sum varchar(30)insert into usera values (51855025,1,1225)insert into usera values (51855025,2,2705)insert into usera values (53711033,1,\'......\')insert into usera values (53711033,2,\'......\')

（省略号代表的是数据。。。。）

selectuserid,sum(if(Type=1,Duration_sum,0)) as Duration_sum_type1,sum(if(Type=2,Duration_sum,0)) as Duration_sum_type2fromuseragroup by userid