我创建了一个视图a,然后执行如下语句会报错
select * from a
union all
select * from a
union all
select * from a
union all
select * from a
报未定义列错误.
如果执行
select * from a
union all
select * from a
union all
select * from a
就不会报错.
三个union all就报错
两个就不报错
请问是什么原因?
select * from a
union all
select * from a
union all
select * from a
union all
select * from a
报未定义列错误.
如果执行
select * from a
union all
select * from a
union all
select * from a
就不会报错.
三个union all就报错
两个就不报错
请问是什么原因?
SQL> CREATE VIEW v_test AS
2 select * from a
3 union all
4 select * from a
5 union all
6 select * from a
7 union all
8 select * from a
9 union all
10 select * from a
11 /View createdSQL> select count(*) from v_test; COUNT(*)
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40