MySQL查询错误。检查行是否存在，更新或插入

以下查询应检查该行是否存在，如果存在，更新（如果不存在），插入。MySQL查询错误。检查行是否存在，更新或插入

String sql = "IF EXISTS (SELECT * FROM 'mocha' WHERE uuid = " + uuid + ")" + 
     "BEGIN" + 
      "UPDATE 'mocha'" + 
      "SET join_message = " + message + 
      "WHERE uuid =" + uuid + 
     "END" + 
     "ELSE" + 
     "BEGIN" + 
      "INSERT INTO 'mocha' (uuid, join_message, quit_message)" + 
      "VALUES ('" + uuid + ", " + message + " + "" + "')" + 
     "END";

我希望自己是能够做到这一点的一个查询，而不是两个，这里就是整个方法：

public void setMessage(UUID uuid, String message) { 
    String sql = "IF EXISTS (SELECT * FROM 'mocha' WHERE uuid = " + uuid + ")" + 
      "BEGIN" + 
       "UPDATE 'mocha'" + 
       "SET join_message = " + message + 
       "WHERE uuid =" + uuid + 
      "END" + 
      "ELSE" + 
      "BEGIN" + 
       "INSERT INTO 'mocha' (uuid, join_message, quit_message)" + 
       "VALUES ('" + uuid + ", " + message + ", ''" + "')" + 
      "END"; 
    BukkitRunnable r = new BukkitRunnable() { 
     @Override 
     public void run() { 
      System.out.println("Join message was set."); 
      try { 
       Statement statement = connection.createStatement(); 
       statement.executeUpdate(sql); 
      } catch(SQLException e) { 
       e.printStackTrace(); 
      } 
     } 
    }; 

    r.runTaskAsynchronously(instance); 
}

不过，我发现了以下错误：

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ''mocha' WHERE uuid = 0f9f822c-d7e6-4000-ac05-6ebc17b82f1d)BEGINUPDATE 'mocha'SET' at line 1 
[10:18:52 WARN]:  at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) 
[10:18:52 WARN]:  at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) 
[10:18:52 WARN]:  at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) 
[10:18:52 WARN]:  at java.lang.reflect.Constructor.newInstance(Unknown Source) 
[10:18:52 WARN]:  at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) 
[10:18:52 WARN]:  at com.mysql.jdbc.Util.getInstance(Util.java:408) 
[10:18:52 WARN]:  at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:943) 
[10:18:52 WARN]:  at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3970) 
[10:18:52 WARN]:  at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3906) 
[10:18:52 WARN]:  at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2524) 
[10:18:52 WARN]:  at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2677) 
[10:18:52 WARN]:  at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2545) 
[10:18:52 WARN]:  at com.mysql.jdbc.StatementImpl.executeUpdateInternal(StatementImpl.java:1540) 
[10:18:52 WARN]:  at com.mysql.jdbc.StatementImpl.executeLargeUpdate(StatementImpl.java:2595) 
[10:18:52 WARN]:  at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1468) 
[10:18:52 WARN]:  at me.Latte.Models.MochaModel$2.run(MochaModel.java:68) 
[10:18:52 WARN]:  at org.bukkit.craftbukkit.v1_11_R1.scheduler.CraftTask.run(CraftTask.java:71) 
[10:18:52 WARN]:  at org.bukkit.craftbukkit.v1_11_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:52) 
[10:18:52 WARN]:  at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) 
[10:18:52 WARN]:  at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) 
[10:18:52 WARN]:  at java.lang.Thread.run(Unknown Source)

我在做什么错？

来源

2017-06-04 kinx

抛开其他问题，你的SQL有一堆话一起运行无空格。打印出来并阅读。 – khelwood

@ khelwood是的，我意识到现在，我无法弄清楚我做错了什么。任何帮助将是值得赞赏的：http://sqlfiddle.com/#!9/4af8f4/4 – kinx

@kinx你可能想看看'REPLACE INTO ...'或'INSERT INTO ... ON DUPLICATE KEY' – Progman

是的，你使用单引号而不是背景名称mocha。所以，你的查询

INSERT INTO 'mocha'

应该

INSERT INTO `mocha`

来源

2017-06-04 14:33:53 Rahul

谢谢，看起来像我的整个队列是错误的。我在这里做错了什么？ http://sqlfiddle.com/#!9/4af8f4/4 – kinx

MySQL查询错误。检查行是否存在，更新或插入

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