从多行插入MS SQL

Question

I´m trying to insert values into a database from several tables:

insert dbo.Table1
(ID, IDTable2, IDCounter)
select
s.ID
o.IDTable2
o.IDCounter
from dbo.table3 as o, dbo.table2 as s

But the above code leads to the situation that i get duplicate values for the values from table 3, where i just want one value from table3 per value from table 2. (The tables don´t have any relationship info)

Thanks in advance.

Edit:

Thanks everyone. I managed to solve it by adding a reference id to table2 and then using an inner join.

Answer 1

You should not use full join as this will lead to table3 rows x table2 rows. Use inner join instead.

Answer 2

You forgot the clause for joining the tables table2 and table3, thus building a cartesian product. There must be something linking the tables; otherwise it makes no sense to combine them as you do.

My advice: Stay away from that old join syntax where you list the tables comma-separated. Use up-to-date join syntax (INNER JOIN ON etc.) instead.

Having said this, I don't see how your select will make sense anyhow. ID is to become the ID of table2 and IDTable2 is to become the ID of table2, too?