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How to update the contents of a ResultSet using a JDBC program?

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2023-08-30 14:57:02723browse

如何使用 JDBC 程序更新 ResultSet 的内容?

To update the contents of the ResultSet you need to create a statement by passing the ResultSet type updatable, as:

//Creating a Statement object
Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_UPDATABLE);

Just like getXXX() and setXXX() The methods are the same, and the ResultSet interface also provides the updateXXX() method to update the content of the rows in the result set.

These methods accept a string value representing the index or column label of the row to be updated.

Please note that the table should have a primary key if you need to update the contents of the ResultSet.

Example

Suppose we have a table named Employees with 5 records as shown below:

+----+---------+--------+----------------+
| Id | Name    | Salary | Location       |
+----+---------+--------+----------------+
|  1 | Amit    | 3000   | Hyderabad      |
|  2 | Kalyan  | 4000   | Vishakhapatnam |
|  3 | Renuka  | 6000   | Delhi          |
|  4 | Archana | 9000   | Mumbai         |
|  5 | Sumith  | 11000  | Hyderabad      |
+----+---------+--------+----------------+

The following example demonstrates how to update the contents of the result set :

import java.sql.*;
public class ResultSetExample {
   public static void main(String[] args) throws Exception {
      //Registering the Driver
      DriverManager.registerDriver(new com.mysql.jdbc.Driver());
      //Getting the connection
      String mysqlUrl = "jdbc:mysql://localhost/TestDB";
      Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
      System.out.println("Connection established......");
      //Creating a Statement object
      Statement stmt = con.createStatement(
      ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
      //Retrieving the data
      ResultSet rs = stmt.executeQuery("select * from Employees");
      //Printing the contents of the table
      System.out.println("Contents of the table: ");
      printRs(rs);
      //Moving the pointer to the starting point in the ResultSet
      rs.beforeFirst();
      //Updating the salary of each employee by 5000
      while(rs.next()){
         //Retrieve by column name
         int newSal = rs.getInt("Salary") + 5000;
         rs.updateInt( "Salary", newSal );
         rs.updateRow();
      }
      System.out.println("Contents of the ResultSet after increasing salaries");
      printRs(rs);
      // Set position to second record first
      rs.beforeFirst();
      rs.absolute(2);
      System.out.println("Record we need to delete: ");
      System.out.print("ID: " + rs.getInt("id"));
      System.out.print(", Salary: " + rs.getInt("Salary"));
      System.out.print(", Name: " + rs.getString("Name"));
      System.out.println(", Location: " + rs.getString("Location"));
      System.out.println(" ");
      //Deleting the row
      rs.deleteRow();
      System.out.println("Contents of the ResultSet after deleting one records...");
      printRs(rs);
      System.out.println("Goodbye!");
   }
   public static void printRs(ResultSet rs) throws SQLException{
      //Ensure we start with first row
      rs.beforeFirst();
      while(rs.next()){
         System.out.print("ID: " + rs.getInt("id"));
         System.out.print(", Salary: " + rs.getInt("Salary"));
         System.out.print(", Name: " + rs.getString("Name"));
         System.out.println(", Location: " + rs.getString("Location"));
      }
      System.out.println();
   }
}

Output

Connection established......
Contents of the table:
ID: 1, Salary: 3000, Name: Amit, Location: Hyderabad
ID: 2, Salary: 4000, Name: Kalyan, Location: Vishakhapatnam
ID: 3, Salary: 6000, Name: Renuka, Location: Delhi
ID: 4, Salary: 9000, Name: Archana, Location: Mumbai
ID: 5, Salary: 11000, Name: Sumith, Location: Hyderabad
Conetnets of the resultset after increaing salaries
ID: 1, Salary: 8000, Name: Amit, Location: Hyderabad
ID: 2, Salary: 9000, Name: Kalyan, Location: Vishakhapatnam
ID: 3, Salary: 11000, Name: Renuka, Location: Delhi
ID: 4, Salary: 14000, Name: Archana, Location: Mumbai
ID: 5, Salary: 16000, Name: Sumith, Location: Hyderabad
Record we need to delete:
ID: 2, Salary: 9000, Name: Kalyan, Location: Vishakhapatnam
Contents of the resultset after deleting one records...
ID: 1, Salary: 8000, Name: Amit, Location: Hyderabad
ID: 3, Salary: 11000, Name: Renuka, Location: Delhi
ID: 4, Salary: 14000, Name: Archana, Location: Mumbai
ID: 5, Salary: 16000, Name: Sumith, Location: Hyderabad
Goodbye!

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