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How to set auto-increment to an existing column in a table using JDBC API?
You can add/set an auto increment constraint to a column in a table using the ALTER TABLE command.
Syntax
ALTER TABLE table_name ADD id INT PRIMARY KEY AUTO_INCREMENT
Assume we have a table named Dispatches in the database with 7 columns namely id, CustomerName, DispatchDate, DeliveryTime, Price and, Location with description as shown below:
+--------------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------------+--------------+------+-----+---------+-------+ | ProductName | varchar(255) | YES | UNI | NULL | | | CustomerName | varchar(255) | YES | | NULL | | | DispatchDate | date | YES | | NULL | | | DeliveryTime | time | YES | | NULL | | | Price | int(11) | YES | | NULL | | | Location | text | YES | | NULL | | | ID | int(11) | NO | PRI | NULL | | +--------------+--------------+------+-----+---------+-------+
Following JDBC program establishes connection with MySQL database ,adds a column named Id and sets the values to the id column as auto-increment.
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
public class SettingAutoIncrement {
public static void main(String args[]) throws SQLException {
//Registering the Driver
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
//Getting the connection
String mysqlUrl = "jdbc:mysql://localhost/mydatabase";
Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
System.out.println("Connection established......");
//Creating the Statement
Statement stmt = con.createStatement();
//Setting the column id auto-increment
String query = "ALTER TABLE Sales ADD id INT PRIMARY KEY AUTO_INCREMENT";
stmt.execute(query);
stmt.executeBatch();
System.out.println("Table altered......");
}
}Output
Connection established...... Table altered......
If you retrieve the contents of the Sales table using the Select command you can observe that a column named id added to the table with auto-incremented integer values.
mysql> select * from Sales; +-------------+--------------+--------------+--------------+-------+----------------+----+ | ProductName | CustomerName | DispatchDate | DeliveryTime | Price | Location | id | +-------------+--------------+--------------+--------------+-------+----------------+----+ | Key-Board | Raja | 2019-09-01 | 08:51:36 | 7000 | Hyderabad | 1 | | Earphones | Roja | 2019-05-01 | 05:54:28 | 2000 | Vishakhapatnam | 2 | | Mouse | Puja | 2019-03-01 | 04:26:38 | 3000 | Vijayawada | 3 | | Mobile | Vanaja | 2019-03-01 | 04:26:35 | 9000 | Vijayawada | 4 | | Headset | Jalaja | 2019-03-01 | 05:19:16 | 6000 | Vijayawada | 5 | +-------------+--------------+--------------+--------------+-------+----------------+----+ 5 rows in set (0.00 sec)
Updated on: 30-Jul-2019
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