MERGE INTO NetworkElementAttributeTypes AS Target
USING (VALUES
(49, N'Lower Leakage limit', 2),
(48, N'Upper Leakage limit', 2)
)

AS Source ([NetworkElementAttributeTypeId], [NetworkElementAttributeTypeName], [AttributeDataTypeId])
ON Target.[NetworkElementAttributeTypeId] = Source.[NetworkElementAttributeTypeId]
-- update matched rows
WHEN MATCHED THEN
UPDATE SET [NetworkElementAttributeTypeId] = Source.[NetworkElementAttributeTypeId],
[NetworkElementAttributeTypeName] = Source.[NetworkElementAttributeTypeName],
[AttributeDataTypeId] = Source.[AttributeDataTypeId]
-- insert new rows
WHEN NOT MATCHED BY TARGET THEN
INSERT ([NetworkElementAttributeTypeId], [NetworkElementAttributeTypeName], [AttributeDataTypeId])
VALUES ([NetworkElementAttributeTypeId],  [NetworkElementAttributeTypeName],[AttributeDataTypeId]) ;