db2设置联合主键
create table table_a  (
   ID_A              VARCHAR(255)                   not null ,
   ID_B              VARCHAR(32)                    not null,
   FOREIGN KEY (ID_A) REFERENCES Table_B (ID_A)
);

alter table table_a add constraint  PK_FA PRIMARY KEY (ID_A , ID_B );

创建表a，外键为表b的主键，增加联合主键