Question

当我在Bluemix上的DashDB（DB2）中创建一个表时，如下所示：

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。

Answer 1

当您查看documentation for dashDB（而不是DB2）时，您会注意到可以创建外键。但是，默认情况下会创建一个按列组织的表。仅支持非强制参照约束。在您的示例中，您需要在语句中添加NOT ENFORCED：

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

Answer 2

默认情况下，在CREATE上，Bluemix上的DashDB表按列排列＆＃39; ... https://www-01.ibm.com/support/knowledgecenter/SSEPGG_10.5.0/com.ibm.db2.luw.admin.dbobj.doc/doc/c0060592.html

这也将禁止为此表类型添加外键约束。

要添加FK，请在ORGANIZE BY ROW语句中添加CREATE TABLE：

CREATE TABLE DEPARTMENT (
    depname CHAR (10) UNIQUE NOT NULL ,
    phone   INTEGER
  ) ORGANIZE BY ROW;

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)
  ) ORGANIZE BY ROW;

ALTER TABLE EMPLOYEE 
 ADD CONSTRAINT EMPLOYEE_PK PRIMARY KEY ( "EmpNr" ) ;

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

无法在Bluemix上的DashDB / DB2中的表上添加外键

2 个答案: