JAVA學習筆記(五十五)- 中繼資料 MetaData和可滾動的結果集

標籤：中繼資料   可滾動的結果集   pstmt   conn   

中繼資料 Meta Data

/* * 中繼資料 Meta Data */public class Test03 {    Connection conn = null;    PreparedStatement pstmt=null;    ResultSet rs = null;    public void test(){        conn=DBUtil.getConnection();        try {            DatabaseMetaData dbmd=conn.getMetaData();             //擷取資料庫中繼資料            System.out.println(dbmd.getDatabaseProductName());            System.out.println(dbmd.getDatabaseProductVersion());            System.out.println(dbmd.getDriverName());            System.out.println(dbmd.getDriverVersion());            pstmt=conn.prepareStatement("select username,password from user");            rs=pstmt.executeQuery();            //擷取結果集中繼資料            ResultSetMetaData rsmd=rs.getMetaData();            System.out.println(rsmd.getColumnCount());            System.out.println(rsmd.getColumnName(1));            System.out.println(rsmd.getColumnName(2));        } catch (SQLException e) {            e.printStackTrace();        }    }    public static void main(String[] args) {        new Test03().test();    }}

可滾動的結果集

/* * 可滾動的結果集 */public class Test04 {    Connection conn = null;    PreparedStatement pstmt = null;    ResultSet rs = null;    // 讀取到指定使用者時插入一條記錄    public void test01() {        String sql = "select * from user";        try {            conn = DBUtil.getConnection();            pstmt = conn.prepareStatement(sql,                    ResultSet.TYPE_SCROLL_INSENSITIVE,                    ResultSet.CONCUR_UPDATABLE);            rs = pstmt.executeQuery(); // 可滾動結果集，可以更新表            while (rs.next()) {                String name = rs.getString("username");                if (name.equals("tom")) {// 判斷當前讀取的使用者                    // 將游標移動到插入行，插入行實際上就是一個緩衝區，用來準備資料                    rs.moveToInsertRow();                    rs.updateString("username", "alex");                    rs.updateString("password", "999");                    // 提交緩衝區中的資料                    rs.insertRow();                    System.out.println("插入使用者成功！");                    // 將游標移動到當前行，即插入記錄前的那條記錄                    rs.moveToCurrentRow();                }                System.out.println(rs.getInt(1) + "," + rs.getString(2) + ","                        + rs.getString(3));            }        } catch (SQLException e) {            e.printStackTrace();        } finally {            DBUtil.closeAll(rs, pstmt, conn);        }    }    // 刪除指定使用者    public void test02() {        String sql = "select * from user";        try {            conn = DBUtil.getConnection();            pstmt = conn.prepareStatement(sql,                    ResultSet.TYPE_SCROLL_INSENSITIVE,                    ResultSet.CONCUR_UPDATABLE);            rs = pstmt.executeQuery();            while (rs.next()) {                String name = rs.getString("username");                if (name.equals("bbb")) {                    rs.deleteRow();// 刪除當前行                    //rs.next();// 刪除後將游標下移                    System.out.println("刪除使用者成功");                }                System.out.println(rs.getInt(1) + "," + rs.getString(2) + ","                        + rs.getString(3));            }        } catch (SQLException e) {            e.printStackTrace();        } finally {            DBUtil.closeAll(rs, pstmt, conn);        }    }    //移動遊標    public void test03() {        String sql = "select * from user";        try {            conn = DBUtil.getConnection();            pstmt = conn.prepareStatement(sql,                    ResultSet.TYPE_SCROLL_INSENSITIVE,                    ResultSet.CONCUR_UPDATABLE);            rs = pstmt.executeQuery();            while (rs.next()) {                String name = rs.getString("username");                if (name.equals("s001")) {                    rs.relative(3);                }                System.out.println(rs.getInt(1) + "," + rs.getString(2) + ","                        + rs.getString(3));            }        } catch (SQLException e) {            e.printStackTrace();        } finally {            DBUtil.closeAll(rs, pstmt, conn);        }    }    public static void main(String[] args) {        new Test04().test03();    }}

JAVA學習筆記(五十五)- 中繼資料 MetaData和可滾動的結果集