无法在 Bluemix 上的 DashDB/DB2 中的表上添加外键

问题描述

当我像这样在 Bluemix 上的 DashDB (DB2) 中创建表时:

When I create a table in DashDB (DB2) on Bluemix like this:

CREATE TABLE DEPARTMENT (
    depname CHAR (10) UNIQUE NOT NULL ,
    phone   INTEGER
  ) ;
ALTER TABLE DEPARTMENT ADD CONSTRAINT DEPARTMENT_PK PRIMARY KEY ( depname ) ;

CREATE TABLE EMPLOYEE (
    "EmpNr"          NUMERIC (3) UNIQUE NOT NULL ,
    empname         CHAR (20) ,
    depname         CHAR (10) ,
    EMPLOYEE2_title CHAR (20)
  );
ALTER TABLE EMPLOYEE ADD CONSTRAINT EMPLOYEE_PK PRIMARY KEY ( "EmpNr" ) ;

ALTER TABLE EMPLOYEE ADD CONSTRAINT EMPLOYEE_DEPARTMENT_FK FOREIGN KEY (depname ) REFERENCES DEPARTMENT ( depname ) ;

Bluemix 不允许为此表类型添加外键约束.

Bluemix disallows adding a Foreign Key constraint for this table type.

推荐答案

当你查看dashDB 文档(不是 DB2)您会注意到可以创建外键.但是，默认情况下创建的表是按列组织的.仅支持非强制引用约束.在您的示例中，您需要在语句中添加 NOT ENFORCED:

When you look at the documentation for dashDB (not DB2) you will notice that foreign keys can be created. However, a table by default is created column-organized. Only non-enforced referential constraints are supported. In your example you would need to add NOT ENFORCED to your statement:

ALTER TABLE EMPLOYEE
 ADD CONSTRAINT EMPLOYEE_DEPARTMENT_FK FOREIGN KEY (depname )
 REFERENCES DEPARTMENT ( depname ) NOT ENFORCED;

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