无法添加主键约束

Question

I'm trying to create a table and add a constraint with alter table but it's not working:

CREATE TABLE customer
(
cust_id NUMBER(3),
cust_name VARCHAR2(3),
phone_no NUMBER(10)
);

ALTER  TABLE  customer
ADD  CONSTRAINT  pk_customer
PRIMARY  KEY  (cust_id);

This is the error:

near "CONSTRAINT": syntax error

What did I do wrong?

Answer 1

for mysql try with

ALTER TABLE customer
ADD PRIMARY KEY(cust_id);

or directly from CREATE TABLE

Attention! : compatible fields types within mysql

CREATE TABLE customer
(
    cust_id NUMBER(3),
    cust_name VARCHAR2(3),
    phone_no NUMBER(10),
    PRIMARY KEY(cust_id)
);

Answer 2

Your statements work well... in Oracle database (12c1 at least).

In order for your query to work in MySQL , you need to change the data types. (see SQL Fiddle ). For example:

CREATE TABLE customer
(
cust_id DECIMAL(3), -- changed here
cust_name VARCHAR(3), -- changed here
phone_no DECIMAL(10) -- changed here
);

ALTER  TABLE  customer
ADD  CONSTRAINT  pk_customer
PRIMARY  KEY  (cust_id);