Question

好的，我又遇到了麻烦。

我的ERD中有查询问题的部分是我的超类，超类如下：

电源（超）非外科学（分）手术（子）药物（分）

主键是'OrderNumber'

在病房工作的工作人员提出项目申请，我想查看所有要求的项目，以及收到并订购所有非药物项目的日期（来自子类别）外科和外科手术）

到目前为止，我有这个：

SELECT requisition.ReqNumber, staff.staffnumber, ward.wardname, itemname
FROM requisition, staff, supply, ward, ward_staff, req_supply, nonsurgical, surgical
WHERE requisition.staffnumber = staff.staffnumber
AND requisition.reqnumber = req_supply.reqnumber
AND supply.ordernumber = req_supply.ordernumber
AND staff.staffnumber = ward_staff.staffnumber
AND ward_staff.wardnumber = ward.wardnumber
AND supply.ordernumber = nonsurgical.ordernumber
OR supply.ordernumber = surgical.ordernumber;

所以基本上如果supercalss的主键与手术中的主键相同......或者与非手术中的相同，请告诉我那个请求！问题在于子课程，但我迷失了

感谢您提供任何帮助

Answer 1

在OR条件周围加上括号以获得正确的顺序。

...
AND (supply.ordernumber = nonsurgical.ordernumber
  OR supply.ordernumber = surgical.ordernumber);

Answer 2

OR运算符的优先级低于AND运算符，因此您需要对最后两个子句使用括号，否则仅满足最后一个OR子句就足够了。

所以：

SELECT requisition.ReqNumber, staff.staffnumber, ward.wardname, itemname
FROM requisition, staff, supply, ward, ward_staff, req_supply, nonsurgical, surgical
WHERE requisition.staffnumber = staff.staffnumber
AND requisition.reqnumber = req_supply.reqnumber
AND supply.ordernumber = req_supply.ordernumber
AND staff.staffnumber = ward_staff.staffnumber
AND ward_staff.wardnumber = ward.wardnumber
AND (supply.ordernumber = nonsurgical.ordernumber
OR supply.ordernumber = surgical.ordernumber);

Answer 3

我遇到了几个AND子句和最终OR子句的类似问题，请尝试围绕括号中的两个ORed子句。

SELECT requisition.ReqNumber, staff.staffnumber, ward.wardname, itemname
FROM requisition, staff, supply, ward, ward_staff, req_supply, nonsurgical, surgical
WHERE requisition.staffnumber = staff.staffnumber
AND requisition.reqnumber = req_supply.reqnumber
AND supply.ordernumber = req_supply.ordernumber
AND staff.staffnumber = ward_staff.staffnumber
AND ward_staff.wardnumber = ward.wardnumber
AND 
(supply.ordernumber = nonsurgical.ordernumber
    OR supply.ordernumber = surgical.ordernumber);

Answer 4

您的主要问题是您使用难以保持直接连接语法。因此，您实际上正在使用左连接。

 SELECT r.ReqNumber,
     St.staffnumber,
     w.wardname, itemname
 FROM requisition r
      Inner join   staff st
        On r.staffnumber = st.staffnumber
      Inner join req_supply rs
        On r.reqnumber = rs.reqnumber
      Inner join supply su
        On su.ordernumber = rs.ordernumber
      Inner join ward_staff wst
        On wst.staffnumber = st.staffnumber
      Inner join ward w
        On w.wardnumber = wst.wardnumber
      Inner join nonsurgical  nsr
        On su.ordernumber = nsr.ordernumber
      Left join surgical sr
        On su.ordernumber = sr.ordernumber ;

mySQL-使用OR语句

4 个答案: