A simple database transaction uses only one of the three execution methods in the
Statement interface:
- public ResultSet executeQuery( String sql ) throws SQLException
It executes an SQL statement that returns a singleResultSetobject. It is for any SQL calls that expect to return data from the database; e.g.,ResultSet rset = stmt.executeQuery( "SELECT ename FROM emp WHERE eid='7772413'" ); - public int executeUpdate( String sql ) throws SQLException
It executes an SQLINSERT,UPDATE, orDELETEstatement. In addition, SQL statements that return nothing, such as SQL DDL statements, can be executed. This method returns the number of affected rows; e.g.,stmt.executeUpdate( "INSERT INTO customers VALUES( 'Pokemon', '123456789', 0 )" ); - public boolean execute( String sql ) throws SQLException
It is for situations in which you do not know whether the SQL being executed is a query or update. For example,try { stmt.execute( "DROP TABLE people" ); stmt.execute( "DROP TYPE person FORCE" ); stmt.execute( "DROP TYPE address FORCE" ); } catch( SQLException e ) { System.out.println( e ); }†This usually happens when the application is executing dynamically created SQL statements.
SQLException provides information on a database access error or other errors.
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