表a
aid   name       mc1       mc1sl   mc2      mc2sl    mc3       mc3sl
1    '张三'    '铅笔'     '20'    '毛笔'   '40'   '卷尺'      '50'
2    '李四'    '毛笔'     '20'    '钢笔'   '40'   '直尺'      '50'


表b
bid    name       pname
1    '钢笔'     '笔'
2    '毛笔'     '笔'
3    '铅笔'     '笔'
4    '卷尺'     '尺'
5    '直尺'     '尺'


输出结果
                             笔                 尺
aid   a.name      铅笔      毛笔   钢笔    直尺   卷尺
1      '张三'     20         40     0       50     0
1      '李四'     0          20    40        0     50

select aid,name,
case when mc1='铅笔' then mc1sl
when mc2='铅笔' then mc2sl 
when mc3='铅笔' then mc3sl
else 0 end "铅笔" ,
case when mc1='毛笔' then mc1sl
when mc2='毛笔' then mc2sl 
when mc3='毛笔' then mc3sl
else 0 end "毛笔" ,
case when mc1='钢笔' then mc1sl
when mc2='钢笔' then mc2sl 
when mc3='钢笔' then mc3sl
else 0 end "钢笔" ,
case when mc1='卷尺' then mc1sl
when mc2='卷尺' then mc2sl 
when mc3='卷尺' then mc3sl
else 0 end "卷尺" ,
case when mc1='直尺' then mc1sl
when mc2='直尺' then mc2sl 
when mc3='直尺' then mc3sl
else 0 end "直尺" 
from a

/*
aid    name    铅笔    毛笔    钢笔    卷尺    直尺
1    张三    20    40    0    50    0
2    李四    0    20    40    0    50