union all 合并三张表

蓝风贝6329

select 合约号,品号,领料纱号,领料标重,null as 缴库纱号,null as 车间改纱号,null as 倒纱,null as 缴库标重,null as 辅纱,null as 辅纱标重 from [领$] union all select 合约号,品号,领料纱号,null as 领料标重,缴库纱号,车间改纱号,倒纱,缴库标重,null as 辅纱,null as 辅纱标重 from [缴$] union all select 合约号,品号,领料纱号,null as 领料标重,缴库纱号,null as 车间改纱号,null as 倒纱,null as 缴库标重,辅纱,辅纱标重 from [辅$]

我用union all 合并领、缴、辅三张表，SQL语句在第一张表上，不知道语句哪里有问题，合并不了

ly

1\谨慎使用Null
2\ 0 as 缴库标重 替代 null as 缴库标重
3\剩下的null,建议用""替代 null

蓝风贝6329

ly 发表于 2016-9-10 07:34
1\谨慎使用Null
2\ 0 as 缴库标重 替代 null as 缴库标重
3\剩下的null,建议用""替代 null

意思是值的地方用0代替null ,其余用""代替null吗