Deleting row and column of a table

Deleting row and column of a table


Posted in : Core Java Posted on : October 18, 2010 at 3:39 PM Comments : [ 0 ]

This section contains the detail about the Deleting row and column of a database table in java.

Deleting row and column of a table

In this program ,we delete row and column of a table. First we create connection to a database using connection interface and java driver. After it we can delete row using "delete " keyword and also can delete column using "Alter" table commands SQL.

For this example, we are using a database named as "cellular" of mysql--

Table : cellular(Before deletion)

In this table, we will delete id having minimum value and we will also delete column "name".

import√?¬†java.sql.*;√?¬†

class√?¬†colerase√?¬†{
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†public√?¬†static√?¬†void√?¬†main(String[]√?¬†args)√?¬†throws√?¬†SQLException√?¬†{

√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†//√?¬†declare√?¬†a√?¬†connection√?¬†by√?¬†using√?¬†Connection√?¬†interface√?¬†
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†Connection√?¬†connection√?¬†=√?¬†null;

√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†

√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†String√?¬†connectionURL√?¬†=√?¬†"jdbc:mysql://192.168.10.13:3306/ankdb";

√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†//declare√?¬†a√?¬†resultSet√?¬†
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†ResultSet√?¬†rs√?¬†=√?¬†null;

√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†//√?¬†Declare√?¬†statement.
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†Statement√?¬†statement√?¬†=√?¬†null;

√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†try√?¬†{

√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†//√?¬†Load√?¬†JDBC√?¬†driver√?¬†"com.mysql.jdbc.Driver".√?¬†
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†Class.forName("com.mysql.jdbc.Driver").newInstance();

√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†connection√?¬†=√?¬†DriverManager.getConnection(connectionURL,
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†"root",√?¬†"root");

√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†statement√?¬†=√?¬†connection.createStatement();

√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†

√?¬†√?¬†√?¬†√?¬†/*√?¬†sql√?¬†query√?¬†find√?¬†the√?¬†element√?¬†from√?¬†the√?¬†table√?¬†havinf√?¬†minimum√?¬†ID√?¬†*/
√?¬†√?¬†√?¬†√?¬†rs√?¬†=√?¬†statement.executeQuery("select√?¬†min(id)√?¬†from√?¬†cellular");
√?¬†√?¬†√?¬†√?¬†rs.next();
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†

√?¬†√?¬†√?¬†√?¬†//√?¬†This√?¬†sql√?¬†query√?¬†delete√?¬†the√?¬†row√?¬†having√?¬†minimum√?¬†ID.
√?¬†statement.executeUpdate("delete√?¬†from√?¬†cellular√?¬†where√?¬†id='"+rs.getInt(1)+"'");√?¬†√?¬†
√?¬†System.out.println("Row√?¬†is√?¬†deleted√?¬†successfully.");

√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†

√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†//√?¬†This√?¬†sql√?¬†query√?¬†delete√?¬†the√?¬†column√?¬†name√?¬†of√?¬†specified√?¬†name.
√?¬†statement.executeUpdate("ALTER√?¬†TABLE√?¬†cellular√?¬†DROP√?¬†name");
√?¬†System.out.println("column√?¬†'Address'√?¬†is√?¬†deleted√?¬†successfully.");

√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†
√?¬†√?¬†√?¬†√?¬†√?¬†}
√?¬†√?¬†√?¬†√?¬†√?¬†//√?¬†catch√?¬†exceptions√?¬†if√?¬†found√?¬†any√?¬†exception√?¬†at√?¬†run√?¬†time.
√?¬†√?¬†√?¬†√?¬†√?¬†catch(Exception√?¬†ex){
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†System.out.println("Sorry√?¬†!√?¬†found√?¬†some√?¬†problems√?¬†with√?¬†database.");
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†System.out.println("Error√?¬†is√?¬†:√?¬†"+√?¬†ex);
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†}

√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†finally√?¬†{
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†//√?¬†close√?¬†all√?¬†the√?¬†connections.
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†rs.close();
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†statement.close();
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†connection.close();
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†}
√?¬†√?¬†√?¬†√?¬†√?¬†√?¬†}
}

Table : cellular(after deletion of minimum "id" value and column "name")

Download Source Code

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