Multiple constraints on single column

oracle10g, sql

Solution

You have wrong syntax when create `null_cons` constraint:

Use this (table level check constraint):

CREATE TABLE x(
    x VARCHAR2(20), 
    y NUMBER(2) NOT NULL,
    CONSTRAINT fk_cons FOREIGN KEY(x) REFERENCES user_info(user_id),
    CONSTRAINT null_cons CHECK(x IS NOT NULL)
)

Or (use `NOT NULL` constraint on column):

CREATE TABLE x(
    x VARCHAR2(20) NOT NULL, 
    y NUMBER(2) NOT NULL,
    CONSTRAINT fk_cons FOREIGN KEY(x) REFERENCES user_info(user_id)
)

Or (Use column level check constraint):

CREATE TABLE x(
    x VARCHAR2(20) CHECK (X IS NOT NULL), 
    y NUMBER(2) NOT NULL,
   CONSTRAINT fk_cons FOREIGN KEY(x) REFERENCES user_info(user_id)
)

Problem

Can we add multiple constraints on a single column? like- ``` create table x(x varchar2(20), y number(2) not null, constraint fk_cons foreign key(x) references user_info(user_id), constraint null_cons not null(x) ) ``` this query is returning error ora-00904: invalid identifier....

Original source