加入两个内连接查询

Question

我有两个查询，我不知道如何将它们连接在一起。 他们在这里：

command.CommandText = "
    SELECT sl.Reg_No,sr.ID_Number,sr.Name,sr.Course,sl.Date,sl.Time_IN,sl.Time_Out,sl.ScheduleId 
    FROM student_logs sl 
         INNER JOIN student_records sr ON sl.Student_Reg_No=sr.Reg_No 
    WHERE sl.date between '" & fromDateTimePicker.Value.ToShortDateString & "' and '" & toDateTimePicker.Value.ToShortDateString & "' 
    ORDER BY Reg_No DESC";

command.CommandText = "
    SELECT sls.StudentLogStatusDescription 
    FROM studentlogstatus sls 
         INNER JOIN student_logs sl ON sls.StudentLogStatusId=sl.StudentLogStatusId  
    ORDER BY Reg_No DESC";

非常感谢你的帮助。

Answer 1

您可以在一个语句中拥有多个联接，因此您可以将这两个语句组合起来：

command.CommandText = 
    "SELECT sl.Reg_No,sr.ID_Number,sr.Name,sr.Course,sl.Date,
        sl.Time_IN,sl.Time_Out,sl.ScheduleId,sls.StudentLogStatusDescription 
    FROM student_logs sl 
        INNER JOIN student_records sr ON sl.Student_Reg_No=sr.Reg_No 
        INNER JOIN studentlogstatus sls 
              ON sls.StudentLogStatusId=sl.StudentLogStatusId  
    WHERE sl.date between '" & fromDateTimePicker.Value.ToShortDateString & 
                  "' and '" & toDateTimePicker.Value.ToShortDateString & "' 
    ORDER BY Reg_No DESC";