什么是存储过程?如何使用JDBC程序调用存储过程?
存储过程是子例程,是SQL语句的一部分,存储在SQL目录中。所有可以访问关系数据库的应用程序(Java,Python,PHP等)都可以访问这些过程。
存储过程包含IN和OUT参数,或同时包含这两个参数。如果您使用SELECT语句,它们可能会返回结果集,它们可以返回多个结果集。
示例
假设我们在MySQL数据库中有一个名为Dispatches的表,其中包含以下数据:
+--------------+------------------+------------------+------------------+| 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 |
+--------------+------------------+------------------+------------------+
并且如果我们创建了一个名为myProcedure的过程来从该表中检索值,如下所示:
Create procedure myProcedure ()-> BEGIN
-> SELECT * from Dispatches;
-> END //
示例
以下是一个JDBC示例,该示例使用JDBC程序调用上述存储过程。
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 {
//注册驱动程序
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
//获得连接
String mysqlUrl = "jdbc:mysql://localhost/sampleDB";
Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
System.out.println("Connection established......");
//准备一个CallableStatement-
CallableStatement cstmt = con.prepareCall("{call myProcedure()}");
//检索结果
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();
}
}
}
输出结果
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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