MSSQL -左与null在右表连接。

I have two tables, tblClient and tblBill which are joined on cltID. Some cltID in tblClient don't have records in tblBill. I want to return all records from tblClient and join tblBill records which are within a date range. If they don't have tblBill records I still want to return that tblClient record.I have two tables, tblClient and tblBill which