sql 查询结果为null的设置默认数据

例如

tabA

id    name

1     tom

2     jack

3     lily

tabB

name    num

tom    5

jack    3

需求结果

id    name    num

1    tom    5

2    jack    3

3    lily    0

mysql写法:

select ta.*,ifnull(tb.num,0) from tabA ta left join tabB tb on ta.name = tb.name;

oracle写法:

select ta.*,nvl(tb.num,0) from tabA ta left join tabB tb on ta.name = tb.name;

mysql写法:

select ta.*,isnull(tb.num,0) from tabA ta left join tabB tb on ta.name = tb.name;

原文：http://7637446.blog.51cto.com/7627446/1363145