If Record Exists, Update Else Insert

Question

I'm trying to move some data between two SQL Server 2008 tables. If the record exists in Table2 with the email from Table1 then update that record with the data from Table1, else insert a new record.

In Table1 I have a number of columns; first name, surname, email and so on.

I'm not quite sure how to structure the query to update Table2 if the email from Table1 exists or insert a new row if email from Table1 does not exist in Table2.

I tried doing a few searches on Google but most solutions seem to work by creating some stored procedure. So I wondered if anyone might know how to build a suitable query that might do the trick?

Answer 1

I think MERGE is what you want.

Answer 2

MERGE
INTO    table2 t2
USING   table1 t1
ON      t2.email = t1.email
WHEN MATCHED THEN
UPDATE
SET     t2.col1 = t1.col1,
        t2.col2 = t1.col2
WHEN NOT MATCHED THEN
INSERT  (col1, col2)
VALUES  (t1.col1, t1.col2)

Answer 3

Microsoft released a tool to compare data between SQL tables, this might a good option in certain situations.

Edit: Forgot to mention, it also generates a script to insert/update missing or different rows.

For completeness, I hacked up this query which does what you want, it updates existing table2 records, and adds those that are missing, based off the email address.

The 'updating' and 'insert missing' queries below are the ones you want.

BEGIN TRAN

create table #table1 (id int, fname varchar(20), email varchar(20))
insert into #table1 values (1, 'name_1_updated', 'email_1')
insert into #table1 values (3, 'name_3_updated', 'email_3')
insert into #table1 values (100, 'name_100', 'email_100')


create table #table2 (id int, fname varchar(20), email varchar(20))
insert into #table2 values (1, 'name_1', 'email_1')
insert into #table2 values (2, 'name_2', 'email_2')
insert into #table2 values (3, 'name_3', 'email_3')
insert into #table2 values (4, 'name_4', 'email_4')

print 'before update'
select * from #table2

print 'updating'
update #table2
set #table2.fname = t1.fname
from #table1 t1
where t1.email = #table2.email

print 'insert missing'
insert into #table2
select * from #table1
where #table1.email not in (select email from #table2 where email = #table1.email)

print 'after update'
select * from #table2

drop table #table1
drop table #table2

ROLLBACK