資料庫查詢的幾種方法
阿新 • • 發佈：2019-01-23
1、Statement介面查詢
這通常是比較常用的。
Statement statement = connection.createStatement();ResultSet rs = getResultSet("SELECT * FROM TB_STUDENTS WHERE AGE=20");...while (rs.next()) 
{ 
...
}
2、PreparedStatement介面查詢
如果需要多次執行SQL語句，那麼PreparedStatement是首選。因為他包含了一個已經被編譯的SQL語句，提高了程式的效率和效能。
下面分別對TB_CUSTOMERS表，進行查詢、插入、修改、刪除的例子。
查詢：
publicvoid preQueryCustomersTB(int ID) { try
{
PreparedStatement pstmt = connection.prepareStatement("SELECT * FROM TB_CUSTOMERS WHERE ID = ?;"); pstmt.setInt(1, ID); pstmt.executeQuery(); connection.commit(); 
}catch (SQLException e) { e.printStackTrace(); } }
插入：
publicboolean preInsertCustomersTB(String company,String name,String address,String email,String phone,String other) try { PreparedStatement pstmt = connection.prepareStatement("INSERT INTO TB_CUSTOMERS (COMPANY,NAME,ADDRESS,EMAIL,PHONE,OTHER) VALUES (?,?,?,?,?,?) ;"); pstmt.setString(1, company); pstmt.setString(2, name); pstmt.setString(3, address); pstmt.setString(4, email); pstmt.setString(5, phone); pstmt.setString(6, other); pstmt.execute(); connection.commit(); }catch (SQLException e) { // TODO 自動生成 catch 塊 e.printStackTrace(); returnfalse; } returntrue; }
修改：
publicboolean preUpdataCustomersTB(int id,String company,String name,String address,String email,String phone,String other) { try { PreparedStatement pstmt = connection.prepareStatement( "update TB_CUSTOMERS SET company = ?, name = ?, address = ?, email = ?, phone = ?, other = ? WHERE ID = ?;"); pstmt.setString(1, company); pstmt.setString(2, name); pstmt.setString(3, address); pstmt.setString(4, email); pstmt.setString(5, phone); pstmt.setString(6, other); pstmt.setInt(7, id); pstmt.execute(); connection.commit(); }catch (SQLException e) { // TODO 自動生成 catch 塊 e.printStackTrace(); returnfalse; } returntrue; }
刪除：
publicvoid preDeletCustomersTB(int RowID) { try { PreparedStatement pstmt = connection.prepareStatement("delete FROM TB_CUSTOMERS where ID = ?;"); pstmt.setInt(1, RowID); pstmt.execute(); connection.commit(); }catch (SQLException e) { // TODO 自動生成 catch 塊 e.printStackTrace(); } }
3、CallableStatement介面查詢
CallableStatement介面提供了通過JDBC API呼叫SQL儲存過程的標準途徑。
使用IN引數的例子：
publicvoid callSetPlayer(String player) { try { CallableStatement cStatement = connection.prepareCall("{CALL setPlayName(?}"); cStatement.setString(1, "John Doe"); cStatement.execute(); }catch (SQLException e) { e.printStackTrace(); } }
使用OUT引數的例子：public String callGetPlayer() { try { CallableStatement cStatement = connection.prepareCall("{CALL getPlayName(?}"); cStatement.registerOutParameter(1, java.sql.Types.VARCHAR); cStatement.execute(); String name = cStatement.getString(1); //...return name; }catch (SQLException e) { e.printStackTrace(); returnnull; } }