Apache Derby - Drop Table

The DROP TABLE statement is used to remove an existing table including all its triggers, constraints, permissions.

Syntax

Following is the Syntax of the DROP TABLE statement.

ij> DROP TABLE table_name;

Example

Suppose you have a table named Student in the database. The following SQL statement deletes a table named Student.

ij> DROP TABLE Student;
0 rows inserted/updated/deleted

Since we have removed the table if we try to describe it, we will get an error as follows

ij> DESCRIBE Student;
IJ ERROR: No table exists with the name STUDENT

Drop Table using JDBC program

This section teaches you how to drop a table in Apache Derby database using JDBC apppcation.

If you want to request the Derby network server using network cpent, make sure that the server is up and running. The class name for the Network cpent driver is org.apache.derby.jdbc.CpentDriver and the URL is jdbc:derby://localhost:1527/DATABASE_NAME;create=true;user=USER_NAME;passw ord=PASSWORD"

Follow the steps given below to drop a table in Apache Derby

Step 1: Register the driver

To communicate with the database, first of all, you need to register the driver. The forName() method of the class Class accepts a String value representing a class name loads it in to the memory, which automatically registers it. Register the driver using this method.

Step 2: Get the connection

In general, the first step we do to communicate to the database is to connect with it. The Connection class represents the physical connection with a database server. You can create a connection object by invoking the getConnection() method of the DriverManager class. Create a connection using this method.

Step 3: Create a statement object

You need to create a Statement or PreparedStatement or, CallableStatement objects to send SQL statements to the database. You can create these using the methods createStatement(), prepareStatement() and, prepareCall() respectively. Create either of these objects using the appropriate method.

Step 4: Execute the query

After creating a statement, you need to execute it. The Statement class provides various methods to execute a query pke the execute() method to execute a statement that returns more than one result set. The executeUpdate() method execute queries pke INSERT, UPDATE, DELETE. The executeQuery() method to results that returns data etc. Use either of these methods and execute the statement created previously.

Example

Following JDBC example demonstrates how to drop a table in Apache Derby using JDBC program. Here, we are connecting to a database named sampleDB (will create if it does not exist) using the embedded driver.

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
pubpc class DropTable {
   pubpc static void main(String args[]) throws Exception {
      //Registering the driver
      Class.forName("org.apache.derby.jdbc.EmbeddedDriver");

      //Getting the Connection object
      String URL = "jdbc:derby:sampleDB;create=true";
      Connection conn = DriverManager.getConnection(URL);

      //Creating the Statement object
      Statement stmt = conn.createStatement();

      //Executing the query
      String query = "DROP TABLE Employees";
      stmt.execute(query);
      System.out.println("Table dropped");
   }
}

Output

On executing the above program, you will get the following output −

Table dropped