SQL Reference - DESCRIBE

Example

DESCRIBE Users;

Output

+--------------+--------------+------+-----+---------+----------------+
| Field        | Type         | Null | Key | Default | Extra          |
+--------------+--------------+------+-----+---------+----------------+
| id           | int(11)      | NO   | PRI | NULL    | auto_increment |
| username     | varchar(100) | YES  |     | NULL    |                |
| email        | varchar(100) | YES  |     | NULL    |                |
| password     | varchar(100) | YES  |     | NULL    |                |
+--------------+--------------+------+-----+---------+----------------+

Explanation

The DESCRIBE statement in MySQL provides a summary of the metadata associated with a specified database table. Here, it describes the structure of the ‘Users’ table including details about each field or column such as name, data type, whether the field can accept null values, the key type, the default value, and any extra information.

Example

DESCRIBE employees;

Output

 Name                      Null?    Type
 ------------------------ -------- ----------------
 EMPLOYEE_ID              NOT NULL NUMBER(6)
 FIRST_NAME                        VARCHAR2(20)
 LAST_NAME               NOT NULL VARCHAR2(25)
 EMAIL                   NOT NULL VARCHAR2(25)
 PHONE_NUMBER                     VARCHAR2(20)
 HIRE_DATE               NOT NULL DATE
 JOB_ID                  NOT NULL VARCHAR2(10)
 SALARY                           NUMBER(8,2)
 COMMISSION_PCT                   NUMBER(2,2)
 MANAGER_ID                       NUMBER(6)
 DEPARTMENT_ID                    NUMBER(4)

Explanation

The DESCRIBE command in the Oracle SQL displays the structure of a table including columns’ names, their type, and whether they can be null or not. In this example, the DESCRIBE employees; command provides the details of the employees table structure.