錯誤在連接器/ J 8.0驅動程序

Question

package abc; 

import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.ResultSet; 
import java.sql.SQLException; 
import com.mysql.cj.jdbc.PreparedStatement; 

public class Test { 

    public static void main(String[] args) throws ClassNotFoundException, SQLException, InstantiationException, IllegalAccessException { 
     Class.forName("com.mysql.cj.jdbc.Driver").newInstance(); 
     Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/tts?autoReconnect=true&useSSL=false", "root", "root"); 

     String sql = "select * from exceldata limit 0,20"; 

     PreparedStatement ps = (PreparedStatement) conn.prepareStatement(sql); 
     ResultSet rs = ps.executeQuery(); 

     while (rs.next()) { 
      System.out.println(rs.getString("fname")); 
     } 
    } 
} 

我在這裏創建了一個簡單的程序，請大家幫忙，並檢查它爲什麼不限制0,10運行。 請不要在這裏我使用MySQL的新驅動程序（Connector/J 8.0）。

Answer 1

我不能重現該問題：

MySQL的：

mysql> SELECT VERSION(); 
+-----------+ 
| VERSION() | 
+-----------+ 
| 5.7.19 | 
+-----------+ 
1 row in set (0.00 sec) 

mysql> USE `tts`; 
Database changed 

mysql> DROP TABLE IF EXISTS `exceldata`; 
Query OK, 0 rows affected (0.00 sec) 

mysql> CREATE TABLE IF NOT EXISTS `exceldata` (
    -> `id` BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY, 
    -> `fname` VARCHAR(100), 
    -> `mobile` CHAR(10), 
    -> `email` VARCHAR(100) 
    ->); 
Query OK, 0 rows affected (0.00 sec) 

mysql> DESC `exceldata`; 
+--------+--------------+------+-----+---------+----------------+ 
| Field | Type   | Null | Key | Default | Extra   | 
+--------+--------------+------+-----+---------+----------------+ 
| id  | bigint(20) | NO | PRI | NULL | auto_increment | 
| fname | varchar(100) | YES |  | NULL |    | 
| mobile | char(10)  | YES |  | NULL |    | 
| email | varchar(100) | YES |  | NULL |    | 
+--------+--------------+------+-----+---------+----------------+ 
4 rows in set (0.00 sec) 

mysql> INSERT INTO `exceldata` 
    -> (`fname`, `mobile`, `email`) 
    -> VALUES 
    -> ('fname 1', 'mobile 1', 'email 1'), 
    -> ('fname 2', 'mobile 2', 'email 2'), 
    -> ('fname 3', 'mobile 3', 'email 3'), 
    -> ('fname 4', 'mobile 4', 'email 4'), 
    -> ('fname 5', 'mobile 5', 'email 5'), 
    -> ('fname 6', 'mobile 6', 'email 6'), 
    -> ('fname 7', 'mobile 7', 'email 7'), 
    -> ('fname 8', 'mobile 8', 'email 8'), 
    -> ('fname 9', 'mobile 9', 'email 9'), 
    -> ('fname 10', 'mobile 10', 'email 10'), 
    -> ('fname 11', 'mobile 11', 'email 11'), 
    -> ('fname 12', 'mobile 12', 'email 12'); 
Query OK, 12 rows affected (0.00 sec) 
Records: 12 Duplicates: 0 Warnings: 0 

mysql> SELECT 
    -> `id`, 
    -> `fname`, 
    -> `mobile`, 
    -> `email` 
    -> FROM 
    -> `exceldata`; 
+----+----------+-----------+----------+ 
| id | fname | mobile | email | 
+----+----------+-----------+----------+ 
| 1 | fname 1 | mobile 1 | email 1 | 
| 2 | fname 2 | mobile 2 | email 2 | 
| 3 | fname 3 | mobile 3 | email 3 | 
| 4 | fname 4 | mobile 4 | email 4 | 
| 5 | fname 5 | mobile 5 | email 5 | 
| 6 | fname 6 | mobile 6 | email 6 | 
| 7 | fname 7 | mobile 7 | email 7 | 
| 8 | fname 8 | mobile 8 | email 8 | 
| 9 | fname 9 | mobile 9 | email 9 | 
| 10 | fname 10 | mobile 10 | email 10 | 
| 11 | fname 11 | mobile 11 | email 11 | 
| 12 | fname 12 | mobile 12 | email 12 | 
+----+----------+-----------+----------+ 
12 rows in set (0.00 sec) 

的Java（文件：Test.java）：

package abc; 

import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.ResultSet; 
import java.sql.SQLException; 
import com.mysql.cj.jdbc.Driver; 
import com.mysql.cj.jdbc.PreparedStatement; 

public class Test { 
    public static void main(String[] args) throws ClassNotFoundException, 
               SQLException, 
               InstantiationException, 
               IllegalAccessException { 
    Driver driver = (Driver) Class.forName("com.mysql.cj.jdbc.Driver").newInstance(); 
    Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/tts?autoReconnect=true&useSSL=false", 
         System.getProperty("mysql.user"), System.getProperty("mysql.password")); 

    System.out.println("Java version: " + System.getProperty("java.version")); 
    System.out.println("Connection: " + conn.getClass().getName()); 
    System.out.println("JDBC driver: " + driver.getMajorVersion() + "." + driver.getMinorVersion()); 

    String sql = "select * from exceldata limit 0,10"; 

    PreparedStatement ps = (PreparedStatement) conn.prepareStatement(sql); 
    ResultSet rs = ps.executeQuery(); 

    while (rs.next()) { 
     System.out.println(rs.getString("fname")); 
    } 
    } 
} 

命令行：

$ javac -d . -cp ./mysql-connector-java-8.0.7-dmr-bin.jar Test.java 
$ java -cp .:./mysql-connector-java-8.0.7-dmr-bin.jar abc.Test 
Java version: 1.8.0_131 
Connection: com.mysql.cj.jdbc.ConnectionImpl 
JDBC driver: 8.0 
fname 1 
fname 2 
fname 3 
fname 4 
fname 5 
fname 6 
fname 7 
fname 8 
fname 9 
fname 10