Connection and Statement Interfaces

Connection interface :

  • A Connection is a session between a Java application and a database.
  • Connection interface methods as follows
public Statement createStatement()creates a statement object that can be used to execute SQL queries.
public void setAutoCommit(boolean status)is used to set the commit status. By default, it is true.
public void commit()saves the changes made since the previous commit/rollback is permanent.
public void rollback()Drops all changes made since the previous commit/rollback.
public void close()closes the connection and Releases a JDBC resources immediately.

Statement interface:

  • The Statement interface provides methods to execute queries with the database.
  • Commonly used methods of Statement interface:

The important methods of Statement interface are as follows:

public ResultSet executeQuery(String sql) is used to execute SELECT query. It returns the object of ResultSet.
public int executeUpdate(String sql) is used to execute specified query, it may be create, drop, insert, update, delete etc.
public boolean execute(String sql)is used to execute queries that may return multiple results.
public int[] executeBatch() is used to execute batch of commands.
This statement is used to execute SQL statements which update or modify databaseThis method is use to execute the SQL statements which retrieve some data from database.This method can be used for any kind of SQL statements.
This method returns an int value which represents number of rows affected by the query.This method returns a ResultSet object which contains the result returned by query.This method returns a Boolean value.
This method is use to execute non select query.This method is use to execute select query.This method is use to execute select and non-select queries.
DML->INSERT, UPDATE and DELETEExample: SELECTAny Type of SQL statements.

Create Statement object:

  • getStatement() method of Connection returns Statement object.
  • Statement interface has functionality to execute different kinds of SQL statements.
    • Statement stmt = con.createStatement();

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