Question

public static boolean saveUserInfo(Client c){ 
try { 
    Statement statement = conn.createStatement(); 
    ResultSet group = statement.executeQuery("SELECT * FROM users WHERE username = '"+ c.playerName + "'"); 


    if (!group.next()) 
     statement.execute("INSERT INTO `users` (`username`, `password`, `rights`, `address`, `hasbankpin`, `bankpin1`, `bankpin2`, `bankpin3`, `bankpin4`, `height`, `posx`, `posy`, `cbowcount`, `vls`, `skulltime`, `ep`, `dpoints`, `vlsleft`) VALUES ('"+c.playerName+"', '"+c.playerPass+"', '"+c.playerRights+"', '"+c.getIP()+"', '"+c.hasBankPin+"', '"+c.bankPin1+"', '"+c.bankPin2+"', '"+c.bankPin3+"', '"+c.bankPin4+"', '"+c.heightLevel+"', '"+c.absX+"', '"+c.absY+"', '"+c.crystalBowArrowCount+"', '"+c.degradeTime+"', '"+c.skullTimer+"', '"+c.earningPotential+"', '"+c.dungeonPoints+"', '"+c.vlsLeft+"')"); 

對不起，我想要做的是檢查用戶是否存在於表中。如果是這樣，我希望它更新它，如果不是，我希望它添加用戶。我一直在嘗試這一兩天，我沒有任何運氣。

任何幫助非常感謝！

Answer 1

您的密碼容易受到SQL Injection的影響。爲了避免這種情況，請使用JAVA PreparedStatement。除此之外，它將允許您在單引號的數據庫中插入記錄。預處理語句的一個例子是這樣的：

PreparedStatement updateSales = con.prepareStatement(
     "INSERT INTO tableName(colA, colB) VALUES (?, ?)"); 
updateSales.setInt(1, 75); 
updateSales.setString(2, "Colombian"); 
updateSales.executeUpdate(); 

記住，總是淨化你的投入。

回到你的問題，你可以使用INSERT...ON DUPLICATE KEY UPDATE

例子，（您的用戶名必須是UNIQUE）

INSERT INTO `users` (`username`, `password`, `rights`, 
        `address`, `hasbankpin`, `bankpin1`, 
        `bankpin2`, `bankpin3`, `bankpin4`, `height`, 
        `posx`, `posy`, `cbowcount`, `vls`, `skulltime`, 
        `ep`, `dpoints`, `vlsleft`) 
VALUES ('','', .....other values...., '') 
ON DUPLICATE KEY 
UPDATE `password` = '', 
     `rights` = '', 
     ... other values here 

Answer 2

您可以使用ON DUPLICATE KEY UPDATE條款做一個的單層查詢：

INSERT INTO table_name(...) 
VALUES(...) 
ON DUPLICATE KEY UPDATE col = value, ...; 

你需要把一個PRIMARY或UNIQUE鍵上username列：

ALTER TABLE users ADD UNIQUE KEY ix1 (username); 

Answer 3

如果你有一個唯一的密鑰，說在username，那麼你可以做這樣的事情：

String query=" 
    INSERT INTO users SET 
     username = ?, 
     password = ?, 
     rights = ?, 
     address = ?, 
     hasbankpin = ?, 
     bankpin1 = ?, 
     bankpin2 = ?, 
     bankpin3 = ?, 
     bankpin4 = ?, 
     height = ?, 
     posx = ?, 
     posy = ?, 
     cbowcount = ?, 
     vls = ?, 
     skulltime = ?, 
     ep = ?, 
     dpoints = ?, 
     vlsleft = ? 
    ON DUPLICATE KEY UPDATE 
     password = VALUES(password), 
     rights = VALUES(rights), 
     address = VALUES(address), 
     hasbankpin = VALUES(hasbankpin), 
     bankpin1 = VALUES(bankpin1), 
     bankpin2 = VALUES(bankpin2), 
     bankpin3 = VALUES(bankpin3), 
     bankpin4 = VALUES(bankpin4), 
     height = VALUES(height), 
     posx = VALUES(posx), 
     posy = VALUES(posy), 
     cbowcount = VALUES(cbowcount), 
     vls = VALUES(vls), 
     skulltime = VALUES(skulltime), 
     ep = VALUES(ep), 
     dpoints = VALUES(dpoints), 
     vlsleft = VALUES(vlsleft) 
"; 

Statement stmt = conn.prepareStatement(query);      

stmt.setString(1, c.playerName); 
stmt.setString(2, c.playerPass); 
stmt.setString(3, c.playerRights); 
stmt.setString(4, c.getIP()); 
stmt.setString(5, c.hasBankPin); 
stmt.setString(6, c.bankPin1); 
stmt.setString(7, c.bankPin2); 
stmt.setString(8, c.bankPin3); 
stmt.setString(9, c.bankPin4); 
stmt.setString(10, c.heightLevel); 
stmt.setString(11, c.absX); 
stmt.setString(12, c.absY); 
stmt.setString(13, c.crystalBowArrowCount); 
stmt.setString(14, c.degradeTime); 
stmt.setString(15, c.skullTimer); 
stmt.setString(16, c.earningPotential); 
stmt.setString(17, c.dungeonPoints); 
stmt.setString(19, c.vlsLeft); 

stmt.executeUpdate();