SQL Server : update and insert in one query - sql

Question

I have some trouble trying to create an update/insert query.
From a .CSV, I create a temporary table (heading and one datarow as a example):
sku
product_id
description_en
description_ru
description_lv
EE1010
4633
Description in Eng
Description in Rus
Description in Lat
I intend to iterate over each row and update/insert rows into another table with this query:
UPDATE ProductLocalized
SET FullDescription = (CASE
WHEN LanguageID = 7 THEN description_en
WHEN LanguageID = 12 THEN description_ru
WHEN LanguageID = 14 THEN description_lv
END)
WHERE LanguageID IN (7, 12, 14)
AND ProductID = product_id;
My problem is how to add the INSERT part if some of the languages missing?

Answer 1

You can use Upsert in SQL to achieve this. Please find below quick example for the same.
create table dbo.test_source
(
id int identity(1,1),
language varchar(50),
description varchar(100)
)
create table dbo.test_dest
(
id int identity(1,1),
language varchar(50),
description varchar(100)
)
Insert into dbo.test_source values ('English', 'British language')
Insert into dbo.test_source values ('Hindi', 'Indian language')
Insert into dbo.test_source values ('Chinese', 'China')
Insert into dbo.test_dest values ('English', 'British language')
Insert into dbo.test_dest values ('Hindi', 'NA')
SELECT * FROM dbo.test_Source
SELECT * FROM dbo.test_Dest
Result
id language description
----------- -------------------------------------------------- ----------------------------------------------------------------------------------------------------
1 English British language
2 Hindi Indian language
3 Chinese China
id language description
----------- ------------------ -------------
1 English British language
2 Hindi NA
MERGE dbo.test_dest as MyTarget
USING
(
SELECT
ID,
Language,
Description
FROM dbo.test_source
) as MySource
ON MyTarget.Language = MySource.Language
WHEN MATCHED AND NOT
(
MySource.Description = ISNULL(MyTarget.Description, '')
)
THEN
UPDATE
Set MyTarget.Description = MySource.Description
WHEN NOT MATCHED BY TARGET
THEN
INSERT (Language, description)
VALUES (MySource.Language
,MySource.Description);
SELECT * FROM dbo.test_Dest
Result
id language description
----------- -------------------------------------------------- ----------------------------------------------------------------------------------------------------
1 English British language
2 Hindi Indian language
3 Chinese China
We can see record with 2 got updated with source table description and record with id 3 got inserted as it was not exist into destination table.

Answer 2

You can use IF EXIST or IF NOT EXIST statements to filter the records and then apply the INSERT or UPDATE Commands.
Example:
IF NOT EXIST ( Condition ) { INSERT }
IF EXIST ( Condition ) { UPDATE }
An alternate way is:
IF EXIST( Condition )
update
ELSE
insert