JAva面接学習ノートの基礎部分

/*クエリーデータのjdbcコード*/

public class TestJDBC {   
  
    public static void main(String[] args) {   
        ResultSet rs = null;   
        Statement stmt = null;   
        Connection conn = null;   
        try {   
            Class.forName("oracle.jdbc.driver.OracleDriver"); //           
            conn = DriverManager.getConnection(   
                    "jdbc:oracle:thin:@localhost:1521:sxt", "scott", "tiger");   
            //         ，sxt          
            stmt = conn.createStatement();   
            rs = stmt.executeQuery("select * from dept");   
            while (rs.next()) {   
                int deptno = rs.getInt("deptno"); //      int     
                String dname = rs.getString("dname"); //      String     
            }   
  
        } catch (ClassNotFoundException e) {   
            e.printStackTrace();   
  
        } catch (SQLException e) {   
            e.printStackTrace();   
        } finally {   
            try {   
                if (rs != null) {   
                    rs.close();   
                    rs = null; //   GC   ，          
                }   
                if (stmt != null) {   
                    stmt.close();   
                    stmt = null; //   GC   ，          
                }   
                if (conn != null) {   
                    conn.close();   
                    conn = null; //   GC   ，          
                }   
            } catch (SQLException e) {   
                e.printStackTrace();   
            }   
        }   
    }   
}  

 
 
/*追加削除を実行するjdbcコード*/

public static void main(String[] args) {   
    Statement stmt = null;   
    Connection conn = null;   
    try {   
        Class.forName("oracle.jdbc.driver.OracleDriver"); //           
        conn = DriverManager.getConnection(   
                "jdbc:oracle:thin:@localhost:1521:sxt", "scott", "tiger");   
        //         ，sxt          
        stmt = conn.createStatement();   
        String sql = "insert into dept2 values (98,'game','fuzhou')";   
        stmt.executeUpdate(sql);   
  
    } catch (ClassNotFoundException e) {   
        e.printStackTrace();   
  
    } catch (SQLException e) {   
        e.printStackTrace();   
    } finally {   
        try {   
  
            if (stmt != null) {   
                stmt.close();   
                stmt = null; //   GC   ，          
            }   
            if (conn != null) {   
                conn.close();   
                conn = null; //   GC   ，          
            }   
  
        } catch (SQLException e) {   
            e.printStackTrace();   
        }   
    }   
}  

 
/*PreparedStatementの使い方*/
 
 
 

public static void main(String[] args) {   
    PreparedStatement pstmt = null;   
    Connection conn = null;   
    try {   
        Class.forName("oracle.jdbc.driver.OracleDriver"); //           
        conn = DriverManager.getConnection(   
                "jdbc:oracle:thin:@localhost:1521:sxt", "scott", "tiger");   
        //         ，sxt          
        String sql = "insert into dept2 values (?,?,?)";   
        pstmt = conn.prepareStatement(sql);   
        pstmt.setInt(1, 98); // id   
        pstmt.setString(2, "game"); //        
        pstmt.setString(3, "fuzhou"); //      
        pstmt.executeUpdate(sql);   
    } catch (ClassNotFoundException e) {   
        e.printStackTrace();   
    } catch (SQLException e) {   
        e.printStackTrace();   
    } finally {   
        try {   
            if (pstmt != null) {   
                pstmt.close();   
                pstmt = null; //   GC   ，          
            }   
            if (conn != null) {   
                conn.close();   
                conn = null; //   GC   ，          
            }   
        } catch (SQLException e) {   
            e.printStackTrace();   
        }   
    }   
}