Foreign keys to same table / Who columns in User table???

Question

Hi All,
We are designing a database for our client and we are using common columns in all tables like CreatedBy and UpdatedBy which are foreign keys to USER table. My question is can we use these two columns in USER table and have the foreign key constraints to the same tables?
USER table script will look like following..
CREATE TABLE XX_USER
     User_ID                              VARCHAR2(10)
,     CreatedBy                         NUMBER(10)
,     UpdatedBy                         NUMBER(10)
,     User_Name                         VARCHAR2(100)     NOT NULL
,     Designation                         VARCHAR2(100)     NOT NULL
,     CONSTRAINT USER_ISACTIVE_CHECK CHECK (Is_Active in ('Y', 'N'))
,     CONSTRAINT USER_KEY PRIMARY KEY (User_ID),
,     CONSTRAINT USER_CREATED_BY FOREIGN KEY (CREATED_BY)
     REFERENCES XX_USER (USER_ID)
,     CONSTRAINT USER_UPDATED_BY FOREIGN KEY (UPDATED_BY)
     REFERENCES XX_USER (USER_ID)
);I think what I am doing (the above script) is not correct. Could someone please suggest me how can solve this issue?
Thanks in advance,
Oraebs

Answer 1

user8644385 wrote:
We are designing a database for our client and we are using common columns in all tables like CreatedBy and UpdatedBy which are foreign keys to USER table. My question is can we use these two columns in USER table and have the foreign key constraints to the same tables?You can. After fixing synatx errors:
SQL> CREATE TABLE XX_USER
  2  (
  3   User_ID        VARCHAR2(10)
  4  , CreatedBy     NUMBER(10)
  5  , UpdatedBy     NUMBER(10)
  6  , User_Name     VARCHAR2(100) NOT NULL
  7  , Designation   VARCHAR2(100) NOT NULL
  8  , Is_Active     VARCHAR2(1)
  9  , CONSTRAINT USER_ISACTIVE_CHECK CHECK (Is_Active in ('Y', 'N'))
10  , CONSTRAINT USER_KEY PRIMARY KEY (User_ID)
11  , CONSTRAINT USER_CREATED_BY FOREIGN KEY (CreatedBy)
12       REFERENCES XX_USER(USER_ID)
13  , CONSTRAINT USER_UPDATED_BY FOREIGN KEY (UpdatedBy)
14       REFERENCES XX_USER(USER_ID)
15  )
16  /
Table created.
SQL> Now USER_ID is a string while CreatedBy/UpdatedBy is a number. Even though it is allowed, it limits USER_ID to numeric strings and causes implicit conversions while validating. So I would change CreatedBy/UpdatedBy data type to VARCHAR2(10).
SY.