什麼是儲存過程?如何使用 JDBC 程式呼叫儲存過程?
儲存過程是子例程,是儲存在 SQL 目錄中的 SQL 語句片段。所有可以訪問關係型資料庫(例如,Java、Python、PHP 等)的應用程式都可以訪問這些過程。
儲存過程包含輸入和輸出引數,或者同時包含這兩個引數。它們可以返回結果集(如果您使用的是 SELECT 語句),也可以返回多個結果集。
示例
假設我們有一個名為Dispatches的 MySQL 資料庫表,其中包含以下資料
+--------------+------------------+------------------+------------------+ | Product_Name | Date_Of_Dispatch | Time_Of_Dispatch | Location | +--------------+------------------+------------------+------------------+ | KeyBoard | 1970-01-19 | 08:51:36 | Hyderabad | | Earphones | 1970-01-19 | 05:54:28 | Vishakhapatnam | | Mouse | 1970-01-19 | 04:26:38 | Vijayawada | +--------------+------------------+------------------+------------------+
如果我們建立了一個名為 myProcedure 的過程,用於從該表中檢索值,如下所示
Create procedure myProcedure () -> BEGIN -> SELECT * from Dispatches; -> END //
示例
以下是一個 JDBC 示例,它使用 JDBC 程式呼叫了上述儲存過程。
import java.sql.CallableStatement; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; public class CallingProcedure { public static void main(String args[]) throws SQLException { //Registering the Driver DriverManager.registerDriver(new com.mysql.jdbc.Driver()); //Getting the connection String mysqlUrl = "jdbc:mysql:///sampleDB"; Connection con = DriverManager.getConnection(mysqlUrl, "root", "password"); System.out.println("Connection established......"); //Preparing a CallableStateement CallableStatement cstmt = con.prepareCall("{call myProcedure()}"); //Retrieving the result ResultSet rs = cstmt.executeQuery(); while(rs.next()) { System.out.println("Product Name: "+rs.getString("Product_Name")); System.out.println("Date Of Dispatch: "+rs.getDate("Date_Of_Dispatch")); System.out.println("Date Of Dispatch: "+rs.getTime("Time_Of_Dispatch")); System.out.println("Location: "+rs.getString("Location")); System.out.println(); } } }
輸出
Connection established...... Product Name: KeyBoard Date of Dispatch: 1970-01-19 Time of Dispatch: 08:51:36 Location: Hyderabad Product Name: Earphones Date of Dispatch: 1970-01-19 Time of Dispatch: 05:54:28 Location: Vishakhapatnam Product Name: Mouse Date of Dispatch: 1970-01-19 Time of Dispatch: 04:26:38 Location: Vijayawada
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