SQL Trick to Join Multiple Select Statements

Don’t overlook the UNION keyword in SQL as a way to simplify selections from multiple tables. For instance, to select the customer with the highest sales from three tables with basically the same layout, use the UNION keyword to allow your VB code to open only one resultset with the answer:

 Private Function MaxCustSales() As Long	Dim sSql as string	sSql =		"select max(cust_sales) max_sales from " & _				"sales.dbo.sales_east " & "UNION " & _				"select max(cust_sales) max_sales from " & _				"sales.dbo.sales_west " & _"UNION " & _				"select max(cust_sales) max_sales from " & _				"sales.dbo.sales_intl " & _				"ORDER BY max_sales DESC"

Do this to open the resultset:

 	If NOT IsNull(!max_sales) Then			MaxCustSales = !max_sales	End IfEnd Function
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