Comparing and Merging two tables in SQL Server 2005 - sql

Question

I have two scripts which produce the following two tables(t1 and t2).
Is there a way of merging t1 and t2 to make t3?
The first 5 rows of each table have the same value in the first column (Number).
However in t1 the columns PreOpOrg and PreOpModality are populated but in t2 they are NULL, and vice versa for columns PostOpOrg and PostOpModality.
So the merge would populate the columns with the non-NULL values from each table (t1 and t2). For the rows in t1 and t2 that only appear in one table then they should appear in t3 as if a normal UNION were being attempted.
Unfortunately while I am working in SQL2005 the script needs to be compatible with SQL2000.
Many thanks.
--t1
Number DateOfBirth PreOpOrg PreOpModality PostOpOrg PostOpModality DiagDate
8643576344 01/04/1935 00:00:00 RBA11 2 NULL NULL 04/09/2012 00:00
2345680016 01/01/1960 00:00:00 RBA11 4 NULL NULL 11/11/2011 00:00
6955934252 20/01/1980 00:00:00 RBA11 4 NULL NULL 22/08/2012 00:00
2234582369 28/12/1940 00:00:00 RBA11 5 NULL NULL 02/11/2011 00:00
9477684368 01/02/1959 00:00:00 RBA11 5 NULL NULL 02/01/2014 00:00
--t2
Number DateOfBirth PreOpOrg PreOpModality PostOpOrg PostOpModality DiagDate
8643576344 01/04/1935 00:00:00 NULL NULL RBA11 2 04/09/2012 00:00
2345680016 01/01/1960 00:00:00 NULL NULL RBA11 2 11/11/2011 00:00
6955934252 20/01/1980 00:00:00 NULL NULL RN325 5 22/08/2012 00:00
2234582369 28/12/1940 00:00:00 NULL NULL RBA11 5 02/11/2011 00:00
9477684368 01/02/1959 00:00:00 NULL NULL RBA11 5 02/01/2014 00:00
0000001564 01/01/1970 00:00:00 NULL NULL RBA11 2 08/08/2012 00:00
4225127842 11/07/1948 00:00:00 NULL NULL RBA11 2 10/09/2011 00:00
0909093842 01/07/1957 00:00:00 NULL NULL RN325 5 26/08/2009 00:00
8528528855 05/12/1969 00:00:00 NULL NULL RBA11 5 25/10/2010 00:00
1000001367 05/05/1950 00:00:00 NULL NULL RBA11 5 08/04/2011 00:00
2234573513 30/11/1946 00:00:00 NULL NULL RN325 5 20/04/2011 00:00
1000001566 18/03/1951 00:00:00 NULL NULL RBA11 5 20/03/2012 00:00
0000001600 01/01/1970 00:00:00 NULL NULL RBA11 5 28/03/2013 00:00
1000001621 12/12/1950 00:00:00 NULL NULL RBA11 5 06/12/2013 00:00
--t3
Number DateOfBirth PreOpOrg PreOpModality PostOpOrg PostOpModality DiagDate
8643576344 01/04/1935 00:00:00 RBA11 2 RBA11 2 04/09/2012 00:00
2345680016 01/01/1960 00:00:00 RBA11 4 RBA11 2 11/11/2011 00:00
6955934252 20/01/1980 00:00:00 RBA11 4 RN325 5 22/08/2012 00:00
2234582369 28/12/1940 00:00:00 RBA11 5 RBA11 5 02/11/2011 00:00
9477684368 01/02/1959 00:00:00 RBA11 5 RBA11 5 02/01/2014 00:00
0000001564 01/01/1970 00:00:00 NULL NULL RBA11 2 08/08/2012 00:00
4225127842 11/07/1948 00:00:00 NULL NULL RBA11 2 10/09/2011 00:00
0909093842 01/07/1957 00:00:00 NULL NULL RN325 5 26/08/2009 00:00
8528528855 05/12/1969 00:00:00 NULL NULL RBA11 5 25/10/2010 00:00
1000001367 05/05/1950 00:00:00 NULL NULL RBA11 5 08/04/2011 00:00
2234573513 30/11/1946 00:00:00 NULL NULL RN325 5 20/04/2011 00:00
1000001566 18/03/1951 00:00:00 NULL NULL RBA11 5 20/03/2012 00:00
0000001600 01/01/1970 00:00:00 NULL NULL RBA11 5 28/03/2013 00:00
1000001621 12/12/1950 00:00:00 NULL NULL RBA11 5 06/12/2013 00:00

Answer 1

Considering to your data and requirement to run on SQL 2000 I am providing you below solution.
Please let me know in case you face any issue. For my convenience I have added only few records from your sample. If you are using SQL Server 2008 or higher version you can use of COALESCE function as explained here.
create table t1
(
Number VARCHAR(10),
DateOfBirth DATETIME,
PreOpOrg VARCHAR(10),
PreOpModality INT,
PostOpOrg VARCHAR(10),
PostOpModality INT,
DiagDate DATETIME
)
create table t2
(
Number VARCHAR(10),
DateOfBirth DATETIME,
PreOpOrg VARCHAR(10),
PreOpModality INT,
PostOpOrg VARCHAR(10),
PostOpModality INT,
DiagDate DATETIME
)
INSERT INTO T1 values (8643576344,'01/04/1935 00:00:00','RBA11',2,NULL,NULL,'04/09/2012 00:00'),
(2345680016,'01/01/1960 00:00:00','RBA11',4,NULL,NULL,'11/11/2011 00:00')
INSERT INTO T2 values ('8643576344','01/04/1935 00:00:00',NULL,NULL,'RBA11',2,'04/09/2012 00:00'),
('0000001564','01/01/1970 00:00:00',NULL,NULL,'RBA11',2,'08/08/2012 00:00'),
('2345680016','01/01/1960 00:00:00',NULL,NULL,'RBA11',2,'11/11/2011 00:00' )
SELECT * FROM T1
SELECT * FROM T2
SELECT CASE WHEN T1.Number IS NOT NULL THEN T1.Number ELSE T2.NUMBER END AS Number,
CASE WHEN T1.DateOfBirth IS NOT NULL THEN T1.DateOfBirth ELSE T2.DateOfBirth END AS DateOfBirth,
CASE WHEN T1.PreOpOrg IS NOT NULL THEN T1.PreOpOrg ELSE T2.PreOpOrg END AS PreOpOrg,
CASE WHEN T1.PreOpModality IS NOT NULL THEN T1.PreOpModality ELSE T2.PreOpModality END AS PreOpModality,
CASE WHEN T1.PostOpOrg IS NOT NULL THEN T1.PostOpOrg ELSE T2.PostOpOrg END AS PostOpOrg,
CASE WHEN T1.PostOpModality IS NOT NULL THEN T1.PostOpModality ELSE T2.PostOpModality END AS PostOpModality,
CASE WHEN T1.DiagDate IS NOT NULL THEN T1.DiagDate ELSE T2.DiagDate END AS DiagDate
FROM T1
RIGHT JOIN T2 ON T1.Number = T2.Number

Answer 2

Another solution can be
SELECT
ISNULL(T1.Number, T2.NUMBER) AS Number
,ISNULL(T1.DateOfBirth, T2.DateOfBirth) AS DateOfBirth
,ISNULL(T1.PreOpOrg, T2.PreOpOrg) AS PreOpOrg
,ISNULL(T1.PreOpModality, T2.PreOpModality) AS PreOpModality
,ISNULL(T1.PostOpOrg, T2.PostOpOrg) AS PostOpOrg
,ISNULL(T1.PostOpModality, T2.PostOpModality) AS PostOpModality
,ISNULL(T1.DiagDate, T2.DiagDate) AS DiagDate
FROM T1
RIGHT JOIN T2
ON T1.Number = T2.Number