JDBC 模糊查询

[苏乐池]

package com.student.www;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Scanner;

public class Test {
public static void main(String[] args) throws Exception {
Class.forName("com.mysql.jdbc.Driver");

Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/Test_Stu?charactEncoding=utf8",
"root", "root");

Statement stat = conn.createStatement();

String input = new Scanner(System.in).nextLine();

String sql = "select * from Student where name like ?";
PreparedStatement pst = conn.prepareStatement(sql);
pst.setString(1, "%"+input+"%");
ResultSet rs = pst.executeQuery();

//ResultSet rs = stat.executeQuery("select * from Student");

while(rs.next()) {

System.out.println("序号:" + rs.getInt("id") + " 名字:" + rs.getString("name") + " 学号:" + rs.getInt("stuID")
+ " 性别:" + rs.getString("gender") + " 地址:" + rs.getString("address"));

}
rs.close();
conn.close();
stat.close();

}
}


//数据库什么都是对的，可以只要是like的模糊查询都不会输出，求大佬解释一下

[usecf]

like ?" 你需要like 什么呢？ 具体要带上参数 你直接?问号 那你还不如select * from Student就行 你要这样用的： SELECT * FROM Persons WHERE City LIKE '%lon%' SELECT * FROM Persons WHERE City LIKE 'N%'

[苏乐池]

String input = new Scanner(System.in).nextLine();

String sql = "select * from Student where name like '%"+input+"%'";
ResultSet rs = stat.executeQuery(sql);


是这样的，我是希望用户自己输入名字中的部分（input）来模糊查询，只是这样我输入了以后不会跳出模糊查询的结果。

[牛肉滚蛋花]

首先看看你的sql在数据库里能不能模糊查询，在跟后台的sql作比较，有可能是参数的问题

[苏乐池]

mysql> select * from Student where name like '%琪%';
+----+-----------+-------+--------+--------------------------------+
| id | name | stuID | gender | address |
+----+-----------+-------+--------+--------------------------------+
| 1 | 琪琪 | 22 | 女 | 上海市浦东新区张江镇 |
| 5 | 琪花 | 11 | 女 | 上海市浦东新区花木镇 |
| 6 | 周琪琪 | 12 | 女 | 上海市金山区 |
+----+-----------+-------+--------+--------------------------------+
3 rows in set (0.00 sec)




package com.student.www;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Scanner;

public class Test {
public static void main(String[] args) throws Exception {
Class.forName("com.mysql.jdbc.Driver");

Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/Test_Stu?charactEncoding=utf8",
"root", "root");

Statement stat = conn.createStatement();

String input = new Scanner(System.in).nextLine();

String sql = "select * from Student where name like concat('%" + input + "%')";
System.out.println(input);
System.out.println(sql);
ResultSet rs = stat.executeQuery(sql);
// PreparedStatement pst = conn.prepareStatement(sql);
// pst.setString(1, "%"+input+"%");
// ResultSet rs = pst.executeQuery();

// ResultSet rs = stat.executeQuery("select * from Student");
while (rs.next()) {
System.err.println(2);
System.out.println("序号:" + rs.getInt("id") + " 名字:" + rs.getString("name") + " 学号:" + rs.getInt("stuID")
+ " 性别:" + rs.getString("gender") + " 地址:" + rs.getString("address"));

}
rs.close();
stat.close();
conn.close();
}
}


//琪
琪
select * from Student where name like concat('%琪%')
//同样的输入