Insert distinct records to table in sqlite3 - sqlite

Question

I want to insert records from first table to second in such a way that only unique records get inserted. That is if table one and two has overlapping (duplicate) records, only the unique records get inserted into table one from table two. For example I have one table named Table_One,
and another table named Table_Two,
now I want to add the records from Table_Two the records that are not already in Table_one which is (XYZ | UVW) so that the output is,
I tried using this technique,
INSERT INTO TableB(Col1, Col2, Col3, ... , Coln)
SELECT DISTINCT A.Col1, A.Col2, A.Col3, ... , A.Coln
FROM TableA A
LEFT JOIN TableB B
ON A.KeyOfTableA = B.KeyOfTableB
WHERE B.KeyOfTableB IS NULL
but the duplicate rows also got inserted, any suggestions as to what could be the solution ??? I am using sqlite3 db.

Answer 1

INSERT INTO TableB (Col1, Col2, Col3, ... , Coln)
SELECT DISTINCT A.Col1,
A.Col2,
A.Col3,
... ,
A.Coln
FROM TableA A
WHERE A.KeyOfTableA NOT IN (SELECT B.KeyOfTableB
FROM TableB B)

Answer 2

Simply use UNION.
Query
sqlite> CREATE TABLE table1(firstName VARCHAR(50),lastName VARCHAR(50));
sqlite> INSERT INTO table1 VALUES('ABC','DEF');
sqlite> INSERT INTO table1 VALUES('GHI','JKL');
sqlite> INSERT INTO table1 VALUES('MNO','PQR');
sqlite>
sqlite> CREATE TABLE table2(first VARCHAR(50),last VARCHAR(50));
sqlite> INSERT INTO table2 VALUES('ABC','DEF');
sqlite> INSERT INTO table2 VALUES('XYZ','UVW');
sqlite> .headers ON
sqlite> SELECT * FROM table1 UNION SELECT * FROm table2;
OUTPUT
firstName|lastName
ABC|DEF
GHI|JKL
MNO|PQR
XYZ|UVW