"ALTER TABLE" Statements

This section describes how to alter a table by adding a new column.

When you are adding new features to an existing database application, very often you need to add new columns to some existing tables. This can be done by using the "ALTER TABLE" statement. Here is a sample Java program that adds a new column called "Discount" to the table "Price":

/* AlterTable.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.sql.*;
public class AlterTable {
  public static void main(String [] args) {
    Connection con = null;
    try {

      con = DriverManager.getConnection(
          "jdbc:sqlserver://localhost\\SQLEXPRESS;"
        + "user=herong;password=T0pSecret;"
        + "database=AdventureWorks2019");

// Adding a new column to an existing table
      Statement sta = con.createStatement();
      int count = sta.executeUpdate(
        "ALTER TABLE Herong.Price ADD Discount REAL");
      System.out.println("A new column added.");
      sta.close();

      DatabaseMetaData meta = con.getMetaData();
      ResultSet res = meta.getColumns(null, null, "Price", null);
      System.out.println("List of columns: ");
      while (res.next()) {
         System.out.println(
           "  "+res.getString("TABLE_SCHEM")
           + ", "+res.getString("TABLE_NAME")
           + ", "+res.getString("COLUMN_NAME")
           + ", "+res.getString("TYPE_NAME")
           + ", "+res.getInt("COLUMN_SIZE")
           + ", "+res.getInt("NULLABLE"));
      }
      res.close();

      con.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

When you run this program, you should get this output:

herong> java -cp .;mssql-jdbc-9.4.1.jre16.jar AlterTable.java

A new column added.
List of columns:
  Herong, Price, ProductID, int, 10, 1
  Herong, Price, Price, real, 24, 1
  Herong, Price, Currency, char, 3, 1
  Herong, Price, Discount, real, 24, 1

Table of Contents

 About This Book

 JDBC (Java Database Connectivity) Introduction

 JDK (Java SE) Installation

 Microsoft SQL Server Express Edition

 Microsoft JDBC Driver for SQL Server

 Microsoft JDBC Driver - Query Statements and Result Sets

 Microsoft JDBC Driver - DatabaseMetaData Object

Microsoft JDBC Driver - DDL Statements

 Executing "Update" Statements - executeUpdate()

 "CREATE SCHEMA" Statements

 "CREATE TABLE" Statements

"ALTER TABLE" Statements

 "DROP TABLE" Statements

 Microsoft JDBC Driver - DML Statements

 SQL Server - PreparedStatement

 SQL Server CLOB (Character Large Object) - TEXT

 SQL Server BLOB (Binary Large Object) - BLOB

 JDBC-ODBC Bridge Driver - sun.jdbc.odbc.JdbcOdbcDriver

 JDBC-ODBC Bridge Driver - Flat Text Files

 JDBC-ODBC Bridge Driver - MS Access

 JDBC-ODBC Bridge Driver - MS SQL Server

 Archived Tutorials

 References

 Full Version in PDF/EPUB