Question

I have a table like so:

column1 column2
------- -------
key1    value1
key1    value2
key1    value3
key2    value4
key2    value5
key2    value6

I would like to create the following two tables:

id column1
-- -------
1  key1
2  key2

key_id column2
------ -------
1      value1
1      value2
1      value3
2      value4
2      value5
2      value6

That is, I would like to split a table into a many-to-one relation between two new tables.

How would I write an SQL query to do this?

Answer 1

Assuming the id column in your first new table is an identity column:

INSERT INTO NewTable1
    (column1)
    SELECT DISTINCT column1
        FROM OldTable;

INSERT INTO NewTable2
    (key_id, column2)
    SELECT n1.id, o.column2
        FROM OldTable o
            INNER JOIN NewTable1 n1
                ON o.column1 = n1.column1;