Compare 2 Sql Tables And Show Data That Are In Table 1 But Not In Table2?

how to compare 2 sql tables and show data that are in table 1 but not in table2?

Dim strSQLL As String = "Select t1.run from ML533 t1 left join portal t2 on t1.[run] = t2.[runNo] where t1.[run] <> t2.[runNo]"
Dim comm As New System.Data.SqlClient.SqlCommand(strSQLL, conn)
Dim ds1 As DataSet = New DataSet()

[code]....

i have tried google and other sites.. but still cannot find solution. maybe i post the wrong question. but i manage to do this code. but its only shows only 1 record missing, but its supposed to show 5 records that r missing.