Question

表格规则：

RuleID    RuleName
1         Rule1
2         Rule2
3         Rule3
4         Rule4

台式设备：

EquipmentID     EquipmentName     EquipmentCode
1               Equip1            E1
2               Equip2            E2
3               Equip3            E3

表RuleEquipment：

EquipmentRuleID   RuleID    EquipmentID
1                 1         1
2                 1         2
3                 2         1
4                 2         3
5                 3         2

用户将使用一个且仅使用一个EquipmentCode进行查询。我想退回没有相关设备或配套设备的规则。

因此，如果用户查询E1，则结果集应为

RuleID    RuleName
1         Rule1
2         Rule2
4         Rule4

我不能把手指放在WHERE子句上。有什么建议吗？

Answer 1

SELECT * FROM Rule 
WHERE Rule.ID NOT IN (SELECT RuleID FROM RuleEquipment)
OR Rule.ID IN 
(
   SELECT RuleID 
   FROM RuleEquipment 
      INNER JOIN Equipment ON RuleEquipment.EquipmentID = Equipment.EquipmentID
   WHERE Equipment.EquipmentCode = @inputEquipmentCode
)

Answer 2

select *
from [Rule] as R
where R.RuleID in (select RE.RuleID
                   from RuleEquipment as RE
                     inner join Equipment as E
                       on RE.EquipmentID = E.EquipmentID
                   where E.EquipmentCode = 'E1') or
      R.RuleID not in (select RE.RuleID
                       from RuleEquipment as RE)

Answer 3

SELECT Rule.*
FROM Rule
LEFT OUTER JOIN RuleEquipment ON RuleEquipment.RuleID = Rule.RuleID
Where Rule.RuleID = 1 or RuleID IS NULL

SQL - 获取匹配为NULL的匹配项或具有一对多的参数

3 个答案: