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JPA许多参考问题

openjpa jpa orm sql java

2

dharga · 技术社区 · 16 年前

我有三张桌子。AvailableOptions和PlantTypeRef,具有名为AvailoptionPlantTypeAssoc的多个关联表。精简的模式如下所示

CREATE TABLE [dbo].[AvailableOptions](
  [SourceApplication] [char](8) NOT NULL,
  [OptionId] [int] IDENTITY(1,1) NOT NULL,
  ...
)

CREATE TABLE [dbo].[AvailOptionPlanTypeAssoc](
  [SourceApplication] [char](8) NOT NULL,
  [OptionId] [int] NOT NULL,
  [PlanTypeCd] [char](2) NOT NULL,
)

CREATE TABLE [dbo].[PlanTypeRef](
  [PlanTypeCd] [char](2) NOT NULL,
  [PlanTypeDesc] [varchar](32) NOT NULL,
)

Java代码如下所示。

//AvailableOption.java
@ManyToMany(cascade={CascadeType.ALL}, fetch=FetchType.EAGER)
@JoinTable(
  name = "AvailOptionPlanTypeAssoc",
  joinColumns = { @JoinColumn(name = "OptionId"),
                  @JoinColumn(name="SourceApplication")},
  inverseJoinColumns=@JoinColumn(name="PlanTypeCd"))
List<PlanType> planTypes = new ArrayList<PlanType>();

//PlanType.java
@ManyToMany
@JoinTable(
  name = "AvailOptionPlanTypeAssoc",
  joinColumns = { @JoinColumn(name = "PlanTypeCd")},
  inverseJoinColumns={@JoinColumn(name="OptionId"),
                      @JoinColumn(name="SourceApplication")})
List<AvailableOption> options = new ArrayList<AvailableOption>();

SELECT t0.OptionId, 
  t0.SourceApplication, 
  t2.PlanTypeCd, 
  t2.EffectiveDate, 
  t2.PlanTypeDesc, 
  t2.SysLstTrxDtm, 
  t2.SysLstUpdtUserId, 
  t2.TermDate 
FROM dbo.AvailableOptions t0 
  INNER JOIN dbo.AvailOptionPlanTypeAssoc t1 
    ON t0.OptionId = t1.OptionId AND t0.SourceApplication = t1.SourceApplication 
  INNER JOIN dbo.AvailableOptions t2 
    ON t1.PlanTypeCd = t2.PlanTypeCd 
WHERE (t0.SourceApplication = ? AND t0.OptionType = ?) 
ORDER BY t0.OptionId ASC, t0.SourceApplication ASC 
[params=(String) testApp, (String) junit0]}

1 回复 | 直到 16 年前

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3

David 16 年前

您正在映射双向关联。这意味着你必须选择一方作为协会的所有者。这一方将负责更新数据库中的关系。

//AvailableOption.java
@ManyToMany(cascade={CascadeType.ALL}, fetch=FetchType.EAGER)
@JoinTable(
  name = "AvailOptionPlanTypeAssoc",
  joinColumns = { @JoinColumn(name = "OptionId"),
                  @JoinColumn(name="SourceApplication")},
  inverseJoinColumns=@JoinColumn(name="PlanTypeCd"))
List<PlanType> planTypes = new ArrayList<PlanType>();

//PlanType.java
@ManyToMany(
    mappedBy = "planTypes"
)
List<AvailableOption> options = new ArrayList<AvailableOption>();

你也可以参考 hibernate annotation documentation chapter 2.2.5

大卫