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法律学如何使用JDBC在PreparedStatement的IN子句中设置参数列表的值？
MySQL数据库中的IN子句用于在查询中指定参数列表。
例如，如果您需要使用特定的ID检索表的内容，您可以使用SELECT语句以及IN子句，如下所示：
mysql> SELECT * from sales where ID IN (1001, 1003, 1005); +------+-------------+--------------+--------------+--------------+-------+------------+ | ID | ProductName | CustomerName | DispatchDate | DeliveryTime | Price | Location | +------+-------------+--------------+--------------+--------------+-------+------------+ | 1001 | Key-Board | Raja | 2019-09-01 | 11:00:00 | 8500 | Hyderabad | | 1003 | Mouse | Puja | 2019-03-01 | 10:59:59 | 4500 | Vijayawada | | 1005 | Headset | Jalaja | 2019-04-06 | 11:08:59 | 7500 | Goa | +------+-------------+--------------+--------------+--------------+-------+------------+ 3 rows in set (0.03 sec)
当在预处理语句中使用IN子句时，您可以为参数列表使用绑定变量（每个参数一个），并使用PreparedStatement接口的setter方法稍后设置这些变量的值，并且在为语句中的所有绑定变量设置值后，您可以使用execute()方法执行该语句。
String query = "UPDATE sales SET price = price+1500 WHERE ProductName IN (?, ?, ? )"; PreparedStatement pstmt = con.prepareStatement(query); pstmt.setString(1, "Key-Board"); pstmt.setString(2, "Mouse"); pstmt.setString(3, "Headset"); pstmt.execute();
示例
让我们在MySQL数据库中创建一个名为sales的表，其中一列是自动递增的，使用CREATE语句如下所示：
CREATE TABLE Sales( ID INT PRIMARY KEY AUTO_INCREMENT, ProductName VARCHAR (20), CustomerName VARCHAR (20), DispatchDate date, DeliveryTime time, Price INT, Location VARCHAR(20) );
现在，我们将使用INSERT语句在sales表中插入5条记录：
insert into sales (ProductName, CustomerName, DispatchDate, DeliveryTime, Price, Location) values('Key-Board', 'Raja', DATE('2019-09-01'), TIME('11:00:00'), 7000, 'India');
insert into sales (ProductName, CustomerName, DispatchDate, DeliveryTime, Price, Location) values('Earphones', 'Roja', DATE('2019-05-01'), TIME('11:00:00'), 2000, 'Vishakhapatnam');
insert into sales (ProductName, CustomerName, DispatchDate, DeliveryTime, Price, Location) values('Mouse', 'Puja', DATE('2019-03-01'), TIME('10:59:59'), 3000, 'Vijayawada');
insert into sales (ProductName, CustomerName, DispatchDate, DeliveryTime, Price, Location) values('Mobile', 'Vanaja', DATE('2019-03-01'), TIME('10:10:52'), 9000, 'Chennai');
insert into sales (ProductName, CustomerName, DispatchDate, DeliveryTime, Price, Location) values('Headset', 'Jalaja', DATE('2019-04-06'), TIME('11:08:59'), 6000, 'Goa');下面的JDBC程序建立与数据库的连接，并使用IN子句将产品键盘、鼠标和耳机的价格分别增加1500。
示例
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class PreparedStatement_IN_clause {
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:///sample_database";
Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
System.out.println("Connection established......");
//Inserting values to a table
String query = "UPDATE sales SET price = price+1500 WHERE ProductName IN (?, ?, ? )";
PreparedStatement pstmt = con.prepareStatement(query);
pstmt.setString(1, "Key-Board");
pstmt.setString(2, "Mouse");
pstmt.setString(3, "Headset");
pstmt.execute();
System.out.println("Price values updated ......");
System.out.println("Contents of the Sales table after the update: ");
//Retrieving data
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("select * from sales");
while(rs.next()) {
System.out.print("Name: "+rs.getString("ProductName")+", ");
System.out.print("Customer Name: "+rs.getString("CustomerName")+", ");
System.out.print("Dispatch Date: "+rs.getDate("DispatchDate")+", ");
System.out.print("Delivery Time: "+rs.getTime("DeliveryTime")+", ");
System.out.print("Price: "+rs.getInt("Price")+", ");
System.out.print("Location: "+rs.getString("Location"));
System.out.println();
}
}
}输出
Connection established...... Price values updated ...... Contents of the Sales table after the update: Name: Key-Board, Customer Name: Raja, Dispatch Date: 2019-09-01, Delivery Time: 11:00:00, Price: 8500, Location: Hyderabad Name: Earphones, Customer Name: Roja, Dispatch Date: 2019-05-01, Delivery Time: 11:00:00, Price: 2000, Location: Vishakhapatnam Name: Mouse, Customer Name: Puja, Dispatch Date: 2019-03-01, Delivery Time: 10:59:59, Price: 4500, Location: Vijayawada Name: Mobile, Customer Name: Vanaja, Dispatch Date: 2019-03-01, Delivery Time: 10:10:52, Price: 9000, Location: Chennai Name: Headset, Customer Name: Jalaja, Dispatch Date: 2019-04-06, Delivery Time: 11:08:59, Price: 7500, Location: Goa
更新于：2019年7月30日
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