336x280(권장), 300x250(권장), 250x250, 200x200 크기의 광고 코드만 넣을 수 있습니다.
1. Either the table level or the column level
** The Oracle server enforces the UNIQUE constaint by implicityly creating a unique index on the unique key column or columns.
CREATE TABLE employees (
employee_id NUMBER(6),
last_name VARCHAR2(25) NOT NULL,
email VARCHAR2(25),
...
...
CONSTRAINT emp_email_uk UNIQUE(email));
employee_id NUMBER(6),
last_name VARCHAR2(25) NOT NULL,
email VARCHAR2(25),
...
...
CONSTRAINT emp_email_uk UNIQUE(email));
** The Oracle server enforces the UNIQUE constaint by implicityly creating a unique index on the unique key column or columns.
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