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Alternatively, CHECK constraints may be may be described separately as a table level constraints, after all, attributes
are described, for example:
CREATE TABLE EMPLOYEE (
ID INT PRIMARY KEY,
FName VARCHAR(20) NOT NULL,
LName VARCHAR(20) NOT NULL,
Gender CHAR(1) NOT NULL,
Address VARCHAR(30),
City VARCHAR(20),
Pin_Code CHAR(6),
DOB DATE,
Salary INT NOT NULL,
Dept_No SMALLINT,
CHECK(Gender = 'M' OR Gender = 'F' OR Gender='O'),
CHECK(Salary BETWEEN 8000 AND 100000)
);#EMPLOYEE
9.5.3 Describe Table
The SQL statement DESCRIBE (or DESC in short) is used to show the structure of a database table. The syntax of the
DESCRIBE statement is as follows:
DESCRIBE table_name;
or
DESC table_name;
On executing the statement:
DESCRIBE EMPLOYEE;
SQL will respond as follows:
Table 9.2: Result of DESCRIBE statement
+----------+-------------+----------+--------+------------+---------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+----------+--------+------------+---------+
| ID | int(11) | NO | PRI | NULL | |
| FName | varchar(20) | NO | | NULL | |
| LName | varchar(20) | NO | | NULL | |
| Gender | char(1) | NO | | NULL | |
| Address | varchar(30) | YES | | NULL | |
| City | varchar(20) | YES | | NULL | |
| Pin_Code | char(6) | YES | | NULL | |
| DOB | date | YES | | NULL | |
| Salary | int(11) | NO | | NULL | |
| Dept_No | smallint(6) | YES | | NULL | |
+----------+-------------+----------+--------+------------+---------+
9.5.4 SHOW TABLES statement
Having created all the tables, we can use the following SQL statement to show the list of tables created in the database
COMPANY as follows:
SHOW TABLES;
Database Concepts and the Structured Query Language 249

