SQL查询从表A中获取表B中每个ID的所有ID，然后插入表C中？

Question

I'm trying to come up with a SQL query that I could easily do in code but is really foreign to me in SQL.

Since I want to be as generic as possible, I wrote out the psuedocode:

foreach (record in TableA)
     foreach (record in TableB)
        var newRecord = new record(TableA.id, TableB.id)
        TableC.Add(newRecord) // TableC.id is autoincremented  
     end foreach
end foreach

Would I use a WHILE loop or is there a better way to accomplish this? I am using SQL Server 2008. Thanks.

Answer 1

You want to think in terms of sets. The operation you are looking for is a cross join . This produces every combination from the two tables (a cartesian product):

select a.id, b.id
from A cross join B

To insert this into a table, you can then use an insert :

insert into c(aid, bid)
    select a.id, b.id
    from A cross join B

Answer 2

Maybe this:

INSERT INTO TableC (ColumnA, ColumnB, ...)
SELECT A.something, B.somethingElse
FROM TableA A
INNER JOIN TableB B ON A.someKey = B.anotherKey
WHERE something = aValue