超过锁定等待超时; 尝试使用JDBC重新启动事务

Question

我有一个名为MySQL表Student有两列Student_id和name.

我使用两个连接对象触发两个查询,它给了我一个例外:

Exception in thread "main" java.sql.SQLException: Lock wait timeout 
exceeded; try restarting transaction
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1074)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4074)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4006)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2468)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2629)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2713)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2663)
    at com.mysql.jdbc.StatementImpl.execute(StatementImpl.java:888)
    at com.mysql.jdbc.StatementImpl.execute(StatementImpl.java:730)
    at jdbc.ConnectUsingJdbc.main(ConnectUsingJdbc.java:19)

以下是产生错误的代码:

package jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

public class ConnectUsingJdbc {

    public static void main(String[] args) 
        throws ClassNotFoundException, SQLException{

        Class.forName("com.mysql.jdbc.Driver");
        Connection connection = DriverManager.getConnection(
            "jdbc:mysql://localhost:3306/test","root","root");
        Connection connection1 = DriverManager.getConnection(
            "jdbc:mysql://localhost:3306/test","root","root");
        connection.setAutoCommit(false);
        connection1.setAutoCommit(false);
        Statement statement = connection.createStatement();
        statement.execute("insert into student values (3,'kamal')");
        Statement statement1 = connection1.createStatement();
        statement1.execute("delete from student where student_id = 3");
        connection.commit();
        connection1.commit();
    }
}

我试图使用connection1我使用另一个connection对象插入的对象删除行.

为什么我收到此错误？

Answer 1

修改您的代码并按如下方式重新排序执行.它应该工作正常:

Statement statement = connection.createStatement();
statement.execute("insert into student values (3,'kamal')");
connection.commit();

Statement statement1 = connection1.createStatement();
statement1.execute("delete from student where student_id = 3");
connection1.commit();

问题是,当您尝试执行新的删除语句在DB中创建死锁情况时,先前执行的insert语句尚未提交并在表上保持锁定.