JDBC Tutorial - JDBC Exceptions Handling

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A SQL exception can occur in the driver or from the database.

For example, a syntax error in the SQL statement will result in a SQL exception. Or we do not have permission to update a table.

When such an exception occurs, an object of type SQLException will be passed to the catch clause.

The SQLException object has the following methods :

Example

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
// w w  w  .ja v  a  2  s  . com
public class Main {
  // JDBC driver name and database URL
  static final String JDBC_DRIVER = "org.hsqldb.jdbcDriver";
  static final String DB_URL = "jdbc:hsqldb:mem:db_file";

  // Database credentials
  static final String USER = "sa";
  static final String PASS = "";

  public static void main(String[] args) {
    Connection conn = null;
    Statement stmt = null;
    try {
      // STEP 2: Register JDBC driver
      Class.forName(JDBC_DRIVER);

      // STEP 3: Open a connection
      System.out.println("Connecting to database...");
      conn = DriverManager.getConnection(DB_URL, USER, PASS);

      // STEP 4: Execute a query
      System.out.println("Creating statement...");
      stmt = conn.createStatement();
      String sql;
      sql = "SELECT id, first, last, age FROM Employees";
      stmt.executeUpdate("CREATE TABLE Employees ( id INTEGER IDENTITY, first VARCHAR(256),  last VARCHAR(256),age INTEGER)");
      stmt.executeUpdate("INSERT INTO Employees VALUES(1,'Jack','Smith', 100)");

      ResultSet rs = stmt.executeQuery(sql);

      // STEP 5: Extract data from result set
      while (rs.next()) {
        // Retrieve by column name
        int id = rs.getInt("id");
        int age = rs.getInt("age");
        String first = rs.getString("first");
        String last = rs.getString("last");

        System.out.print("ID: " + id);
        System.out.print(", Age: " + age);
        System.out.print(", First: " + first);
        System.out.println(", Last: " + last);
      }
      // STEP 6: Clean-up environment
      rs.close();
      stmt.close();
      conn.close();
    } catch (SQLException se) {
      se.printStackTrace();
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      // finally block used to close resources
      try {
        if (stmt != null)
          stmt.close();
      } catch (SQLException se2) {
      }
      try {
        if (conn != null)
          conn.close();
      } catch (SQLException se) {
        se.printStackTrace();
      }
    }
    System.out.println("Goodbye!");
  }
}

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