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How to retrieve auto-incremented value generated by PreparedStatement using JDBC?
While creating a table, in certain scenarios, we need values to column such as ID, to be generated/incremented automatically. Various databases support this feature in different ways.
In MySQL database you can declare a column auto increment using the following syntax.
CREATE TABLE table_name( ID INT PRIMARY KEY AUTO_INCREMENT, column_name1 data_type1, column_name2 data_type2, column_name3 data_type3, column_name4 data_type4, ............ ........... );
While inserting records in a table there is no need to insert value under the auto-incremented column. These will be generated automatically.
For example, in a table if we have a column with name ID and data type INT, which is auto-incremented and, if we already have 6 records in that table. When you insert the next record using the INSERT statement the ID value of the new record will be 7 and the ID value of its next record will be 8.
(You can specify the initial value and interval for these auto-incremented columns).
Retrieving the auto-incremented values
If you insert records into a table which contains auto-incremented column, using a PreparedStatement object.
You can retrieve the values of that particular column, generated by the current PreparedStatement object using the getGeneratedKeys() method.
Example
Let us create a table with name sales in MySQL database, with one of the columns as auto-incremented, using CREATE statement as shown below −
CREATE TABLE Sales( ID INT PRIMARY KEY AUTO_INCREMENT, ProductName VARCHAR (20), CustomerName VARCHAR (20), DispatchDate date, DeliveryTime time, Price INT, Location VARCHAR(20) );
Now, to insert records into this table using PreparedStatement object and, to retrieve the auto-incremented values generated by it −
- Register the Driver class of the desired database using the registerDriver() method of the DriverManager class or, the forName() method of the class named Class.
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
- Create a Connection object by passing the URL of the database, user-name and password of a user in the database (in string format) as parameters to the getConnection() method of the DriverManager class.
Connection mysqlCon = DriverManager.getConnection(mysqlUrl, "root", "password");
- Create a PreparedStatement object using the prepareStatement() method of the connection interface.
To this method pass the INSERT statement with bind variables in string format as one parameter and, Statement.RETURN_GENERATED_KEYS as other parameter as −
//Query to Insert values to the sales table String insertQuery = "INSERT INTO Sales (ProductName, CustomerName, DispatchDate, DeliveryTime, Price, Location) VALUES (?, ?, ?, ?, ?, ?)"; //Creating a PreparedStatement object PreparedStatement pstmt = con.prepareStatement(insertQuery, Statement.RETURN_GENERATED_KEYS);
- Set values of each record to the bind variables using the setXXX() methods and, add it to batch.
pstmt.setString(1, "Key-Board"); pstmt.setString(2, "Raja"); pstmt.setDate(3, new Date(1567315800000L)); pstmt.setTime(4, new Time(1567315800000L)); pstmt.setInt(5, 7000); pstmt.setString(6, "Hyderabad"); pstmt.addBatch(); pstmt.setString(1, "Earphones"); pstmt.setString(2, "Roja"); pstmt.setDate(3, new Date(1556688600000L)); pstmt.setTime(4, new Time(1556688600000L)); pstmt.setInt(5, 2000); pstmt.setString(6, "Vishakhapatnam"); pstmt.addBatch(); ........... ...........
After adding values of all the records to the batch, execute the batch using the executeBatch() method.
pstmt.executeBatch();
- Finally, get the auto-incremented keys generated by this PreparedStatement object using the getGeneratedKeys() method.
ResultSet rs = pstmt.getGeneratedKeys();
while (rs.next()) {
System.out.println(rs.getString(1));
}Following JDBC program inserts 5 records into the Sales table (created above) using PreparedStatement, retrieves and displays the auto-incremented values generated by it.
Example
import java.sql.Connection;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Time;
public class RetrievingData_AutoIncrement_Pstmt {
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/sample_database";
Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
System.out.println("Connection established......");
//Query to Insert values to the sales table
String insertQuery = "INSERT INTO Sales (ProductName, CustomerName, DispatchDate, DeliveryTime, Price, Location) VALUES (?, ?, ?, ?, ?, ?)";
//Creating a PreparedStatement object
PreparedStatement pstmt = con.prepareStatement(insertQuery,Statement.RETURN_GENERATED_KEYS);
pstmt.setString(1, "Key-Board");
pstmt.setString(2, "Raja");
pstmt.setDate(3, new Date(1567315800000L));
pstmt.setTime(4, new Time(1567315800000L));
pstmt.setInt(5, 7000);
pstmt.setString(6, "Hyderabad");
pstmt.addBatch();
pstmt.setString(1, "Earphones");
pstmt.setString(2, "Roja");
pstmt.setDate(3, new Date(1556688600000L));
pstmt.setTime(4, new Time(1556688600000L));
pstmt.setInt(5, 2000);
pstmt.setString(6, "Vishakhapatnam");
pstmt.addBatch();
pstmt.setString(1, "Mouse");
pstmt.setString(2, "Puja");
pstmt.setDate(3, new Date(1551418199000L));
pstmt.setTime(4, new Time(1551418199000L));
pstmt.setInt(5, 3000);
pstmt.setString(6, "Vijayawada");
pstmt.addBatch();
pstmt.setString(1, "Mobile");
pstmt.setString(2, "Vanaja");
pstmt.setDate(3, new Date(1551415252000L));
pstmt.setTime(4, new Time(1551415252000L));
pstmt.setInt(5, 9000);
pstmt.setString(6, "Chennai");
pstmt.addBatch();
pstmt.setString(1, "Headset");
pstmt.setString(2, "Jalaja");
pstmt.setDate(3, new Date(1554529139000L));
pstmt.setTime(4, new Time(1554529139000L));
pstmt.setInt(5, 6000);
pstmt.setString(6, "Goa");
pstmt.addBatch();
System.out.println("Records inserted......");
//Executing the batch
pstmt.executeBatch();
//Auto-incremented values generated by the current PreparedStatement object
ResultSet res = pstmt.getGeneratedKeys();
System.out.println("Auto-incremented values of the column ID generated by the current PreparedStatement object: ");
while (res.next()) {
System.out.println(res.getString(1));
}
}
}Output
Connection established...... Records inserted...... Auto-incremented values of the column ID generated by the current PreparedStatement object: 1 2 3 4 5
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