sql错误

declare @adnum int 

      

        Declare @sql_adnum2 nvarchar(500)

      set @sql_adnum2 = 'SELECT @adnum = COUNT(AdminInfo.AdminID)

	  FROM AdminInfo INNER JOIN

      AdminGrade ON AdminInfo.AdminGradeID = AdminGrade.AdminGradeID INNER JOIN

      Sub_department ON 

      AdminInfo.Sub_departmentID = Sub_department.Sub_departmentID

      where AdminInfo.Active = ''true'' and Sub_department.Sub_departmentID = '''+cast(@Sub_departmentID as nvarchar(4))+'''

      '

      	  exec (@sql_adnum2)

	  select @adnum