SQL Server Union si une table existe

DECLARE @temp TABLE(empName varchar(100),empStoreNum varchar(100),empSales int,location varchar(20))
if object_id('table1') Is not null
insert into @temp
Select empName, empStoreNum, empSales, 'East' As SalesDistrict
FROM store1

if object_id('table2') is not null
insert into @temp
Select empName, empStoreNum, empSales, 'East' As SalesDistrict
FROM store2

if object_id('table3') is not null
insert into @temp
Select empName, empStoreNum, empSales, 'East' As SalesDistrict
FROM store3


select empName, empStoreNum, empSales,location
from @temp
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