A、SELECT s.AgentName,SUM(ISNULL(o.OrderTotal,0.00))AS SumOrderTotalFROM SalesAgents JOIN OrderHeader o ON s.AgentID=o.AgentIDWHERE o.OrderDate BETWEEN @FromDate AND @ToDateGROUP BY s.AgentName B、SELECT s.AgentName, SUM(ISNULL (o.OrderTotal,0.00))AS SumOrderTotalFROM SalesAgent s JOIN OrderHeader o ON s.AgentID = o.AgentIDWHERE o.OrderDate BETWEEN @FromDate AND @ToDate AND o.OrderTotal >= 2000GROUP BY s.AgentName C、SELECT s.AgentName, SUM(ISNULL (o.OrderTotal,0.00)) AS SumOrderTotalFROM SalesAgent s JOIN OrderHeader o ON s.AgentID=o.AgentID WHERE o.OrderDate BETWEEN @FromDate AND@ToDateGROUP BY s.AgentNameHAVING SUM(o.OrderTotal)>=2000 D、SELECT s.AgentName, SUM(ISNULL(o.OrderTotal,0.00)) AS SumOrderTotalFROM SalesAgent s JOIN OrderHeader o ON s.AgentID=o.AgentIDWHERE o.ordertotal=2000 AND o.OrderDate BETWEEN @FromDate AND @ToDateGROUP BY s.AgentNameHAVING SUM(o.OrderTotal) >= 2000