merging content of two tables without duplicating content - sql

Question

I have two identical SQL Server tables (SOURCE and DESTINATION) with lots a columns in each. I want to insert into table DESTINATION rows from table SOURCE that do not already exist in table DESTINATION. I define equality between the two rows if all columns match except for the timestamp, a count column, and the integer primary key. So I want to insert into DESTINATION all rows in SOURCE that dont already exist in DESTINATIONignoring count, timestamp, and the primary key columns.
How do I do this?
Thanks for all the contributions! I chose to use the Merge command since it is structured to allow for updates and inserts in one statement and I needed to do the update separately.
this is the code that worked:
Merge
into DESTINATION as D
using SOURCE as S
on (
D.Col1 = S.Col1
and D.Col2 = S.Col2
and D.Col3 = S.Col3
)
WHEN MATCHED
THEN UPDATE SET D.Count = S.Count
WHEN NOT MATCHED THEN
INSERT (Col1, Col2, Col3, Count, timestamp)
VALUES (S.Col1, S.Col2, S.Col3, S.Count, S.timestamp);
note: when I wrote this question first I called the tables AAA and BBB. I edited and changed the names of AAA to SOURCE AND BBB to DESTINATION for clarity

Answer 1

using Select statement for this purpose since Sql Server 2008 is obsolete instead of Select You can use Merge statement :
ref:
http://technet.microsoft.com/en-us/library/bb510625.aspx
http://weblogs.sqlteam.com/peterl/archive/2007/09/20/Example-of-MERGE-in-SQL-Server-2008.aspx

Answer 2

Something like this:
INSERT INTO BBB(id, timestamp, mycount, col1, col2, col3, etc.)
SELECT id, timestamp, mycount, col1, col2, col3, etc.
FROM AAA
WHERE
NOT EXISTS(SELECT NULL FROM BBB oldb WHERE
oldb.col1 = AAA.col1
AND oldb.col2 = AAA.col2
AND oldb.col3 = AAA.col3
)
Add columns as needed to the NOT EXISTS clause.

Answer 3

A solution using good ol'-fashioned LEFT JOIN -- note in the example below, only the first row of BBB is inserted into AAA, because only it has no matching row in AAA. You'd replace col1 and col2 with the actual columns of the tables.
> select * from AAA;
+---------------------+------+------+
| timestamp | col1 | col2 |
+---------------------+------+------+
| 2012-03-17 08:17:22 | 1 | 1 |
| 2012-03-17 08:17:27 | 1 | 2 |
| 2012-03-17 08:17:30 | 1 | 3 |
| 2012-03-17 08:17:32 | 1 | 4 |
| 2012-03-17 08:17:49 | 2 | 2 |
| 2012-03-17 08:17:52 | 2 | 3 |
| 2012-03-17 08:17:54 | 2 | 4 |
+---------------------+------+------+
7 rows in set (0.00 sec)
> select * from BBB;
+---------------------+------+------+
| timestamp | col1 | col2 |
+---------------------+------+------+
| 2012-03-17 08:18:16 | 2 | 1 |
| 2012-03-17 08:18:18 | 2 | 2 |
| 2012-03-17 08:18:20 | 2 | 3 |
+---------------------+------+------+
3 rows in set (0.00 sec)
> INSERT INTO AAA
SELECT BBB.* FROM BBB
LEFT JOIN AAA
USING(col1,col2)
WHERE AAA.timestamp IS NULL;
> select * from AAA;
+---------------------+------+------+
| timestamp | col1 | col2 |
+---------------------+------+------+
| 2012-03-17 08:17:22 | 1 | 1 |
| 2012-03-17 08:17:27 | 1 | 2 |
| 2012-03-17 08:17:30 | 1 | 3 |
| 2012-03-17 08:17:32 | 1 | 4 |
| 2012-03-17 08:17:49 | 2 | 2 |
| 2012-03-17 08:17:52 | 2 | 3 |
| 2012-03-17 08:17:54 | 2 | 4 |
| 2012-03-17 08:18:16 | 2 | 1 |
+---------------------+------+------+
8 rows in set (0.00 sec)