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Help with T SQL statement
I have very limited Microsoft SQL experience but need an efficient way to do this.
Table1
field1 field2 field3
Table2
field1 field2 field4
I want to work through table1 - first to last
check table2 for match on table1.field1 = table2.field1 and table2.field4 = 'Y'
if no match
create new record in table2
if match and table1.field2 <> table2.field2
update table2.field4
create new record in table2
Any help appreciated
Table1
field1 field2 field3
Table2
field1 field2 field4
I want to work through table1 - first to last
check table2 for match on table1.field1 = table2.field1 and table2.field4 = 'Y'
if no match
create new record in table2
if match and table1.field2 <> table2.field2
update table2.field4
create new record in table2
Any help appreciated
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hmm, not sure about your exact logic, but take a look at MERGE, e.g.
MERGE Table2 Dst
USING ( SELECT T.Column1 ,
T.Column2 ,
T.Column3
FROM Table1 T ) Src
ON ( Dst.Column1 = Src.Column1
AND Dst.Column2 != SrcColumn2
AND Dst.Column4 = 'Y' )
WHEN MATCHED THEN UPDATE SET Dst.Column4 = '?'
WHEN NOT MATCHED THEN INSERT ( Column1 ,
Column2 ,
Column4 )
VALUES ( Src.Column1, Column2, '?' )
OUTPUT DELETED.* ,
$ACTION ,
INSERTED.*;
update table2.field4
create new record in table2
-- Create a temporary table variable to hold the output actions.
DECLARE @changes TABLE(Change VARCHAR(20), T2RecordID, T2Field1, T2Field2, T2Field4, T2OldField4 );
MERGE Table2 as target
USING Table1 as source
ON ( target.field1 = source.field1 AND target.Column4 = 'Y' )
WHEN NOT MATCHED THEN INSERT ( fiel1, field2, field4 )
VALUES ( source.field1, source.field2, 'Y' )
WHEN MATCHED AND target.field2 <> source.field2 THEN UPDATE SET target.Column4 = '?'
OUTPUT $action, inserted.id /*assuming an autonumber field here*/, inserted.field1, inserted.field2, inserted.field4, deleted.field4 INTO @changes;
--@changes will now contain a record of all the changes that have been made. Use this data to do the "create new record in table2" as necessary.
Sorry if I haven't explained the logic very well.
If I get a match on "check table2 for match on table1.field1 = table2.field1 and table2.field4 = 'Y'"
and also table1.field2 <> table2.field2
I need to update table2.field2 in the matched record and then create a new record in table 2
If I get a match on "check table2 for match on table1.field1 = table2.field1 and table2.field4 = 'Y'"
and also table1.field2 = table2.field2 I do nothing
If I get a match on "check table2 for match on table1.field1 = table2.field1 and table2.field4 = 'Y'"
and also table1.field2 <> table2.field2
I need to update table2.field2 in the matched record and then create a new record in table 2
If I get a match on "check table2 for match on table1.field1 = table2.field1 and table2.field4 = 'Y'"
and also table1.field2 = table2.field2 I do nothing
I don't know what you want to put in "field4" in the new row, so you'll have to fill that in below. I'm also assuming field2 can't be NULL -- if it can be, we'll have to adjust the comparison on field2.
INSERT INTO Table2 ( field1, field2, field4 )
SELECT t1.field1, t1.field2, ?.?
FROM Table1 t1
INNER JOIN Table2 t2 ON t2.field1 = t1.field1 AND t2.field4 = 'Y' AND t2.field2 <> t1.field2
UPDATE t2
SET field2 = t1.field2
FROM Table2 t2
INNER JOIN Table2 t2 ON t2.field1 = t1.field1 AND t2.field4 = 'Y' AND t2.field2 <> t1.field2
INSERT INTO Table2 ( field1, field2, field4 )
SELECT t1.field1, t1.field2, ?.?
FROM Table1 t1
INNER JOIN Table2 t2 ON t2.field1 = t1.field1 AND t2.field4 = 'Y' AND t2.field2 <> t1.field2
UPDATE t2
SET field2 = t1.field2
FROM Table2 t2
INNER JOIN Table2 t2 ON t2.field1 = t1.field1 AND t2.field4 = 'Y' AND t2.field2 <> t1.field2
Thanks Scott. I think the only bit missing is create a new record in table2 if there is no match with table1?
Thanks
Thanks
So you also want to INSERT if there's no match at all on table2??
--first:
INSERT INTO Table2 ( field1, field2, field4 )
SELECT t1.field1, t1.field2, ?.?
FROM Table1 t1
LEFT OUTER JOIN Table2 t2 ON t2.field1 = t1.field1 AND t2.field4 = 'Y' AND t2.field2 <> t1.field2
WHERE t2.field1 IS NULL
--then:
UPDATE t2
SET field2 = t1.field2
FROM Table2 t2
INNER JOIN Table2 t2 ON t2.field1 = t1.field1 AND t2.field4 = 'Y' AND t2.field2 <> t1.field2
--first:
INSERT INTO Table2 ( field1, field2, field4 )
SELECT t1.field1, t1.field2, ?.?
FROM Table1 t1
LEFT OUTER JOIN Table2 t2 ON t2.field1 = t1.field1 AND t2.field4 = 'Y' AND t2.field2 <> t1.field2
WHERE t2.field1 IS NULL
--then:
UPDATE t2
SET field2 = t1.field2
FROM Table2 t2
INNER JOIN Table2 t2 ON t2.field1 = t1.field1 AND t2.field4 = 'Y' AND t2.field2 <> t1.field2
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