[我在Java中执行更新查询时遇到Sql语法错误（java.sql.sqlsyntaxerrorexception，您的sql语法有错误）

Question

ERROR =（java.sql.SQL.SyntaxErrorException：您的SQL语法有错误；请查看与您的MySQL服务器版本相对应的手册，以在'？，Last_Name = ?、 Contact =？附近使用正确的语法。第1行的Email_ID =？WHERE用户名= aman036'

我是编程的初学者，所以将不胜感激。这是我的代码：-

   Connection Con=null;
   PreparedStatement pst=null;
   ResultSet rs=null;

    String query="UPDATE cashier SET First_Name=?, Last_Name=?, Contact=?, Email_ID=?  WHERE Username=?";
    try{
        Class.forName("com.mysql.cj.jdbc.Driver");
        Con=DriverManager.getConnection("jdbc:mysql://localhost/billing","Aman","Amanbhattt");
        pst=Con.prepareStatement(query);
        pst.setString(1,NameField.getText());
        pst.setString(2,LastNameField.getText());
        pst.setString(3,ContactField.getText());
        pst.setString(4,EmailField.getText());
        pst.setString(5,UsernameField.getText());
        pst.executeUpdate(query);
        JOptionPane.showMessageDialog(null,"Data Updated Successfully");
        Con.close();

Answer 1

@ Aman

我没有得到您的全部错误，但是从您的代码中我确定您没有在代码中处理sql特殊字符。您需要为SQL查询添加转义字符。

MySQL server version for the right syntax to use near '?, Last_Name=?, Contact=?, Email_ID=? WHERE Username=aman036' 

在您的错误消息中，我可以看到用户名后带有单引号aman036'，因此您需要删除该用户名。

请使用以下代码删除SQL查询字符串中的特殊字符

public String escapeMetaCharacters(String inputString){
    final String[] metaCharacters = {"\\","^","$","{","}","[","]","(",")",".","*","+","?","|","<",">","-","&","%"};

    for (int i = 0 ; i < metaCharacters.length ; i++){
        if(inputString.contains(metaCharacters[i])){
            inputString = inputString.replace(metaCharacters[i],"\\"+metaCharacters[i]);
        }
    }
    return inputString;
}

String query="UPDATE cashier SET First_Name=?, Last_Name=?, Contact=?, Email_ID=?  WHERE Username=?";
try{
    Class.forName("com.mysql.cj.jdbc.Driver");
    Con=DriverManager.getConnection("jdbc:mysql://localhost/billing","Aman","Amanbhattt");
    pst=Con.prepareStatement(query);
    pst.setString(1,escapeMetaCharacters(NameField.getText()));
    pst.setString(2,escapeMetaCharacters(LastNameField.getText()));
    pst.setString(3,escapeMetaCharacters(ContactField.getText()));
    pst.setString(4,escapeMetaCharacters(EmailField.getText()));
    pst.setString(5,escapeMetaCharacters(UsernameField.getText()));
    pst.executeUpdate(query);
    JOptionPane.showMessageDialog(null,"Data Updated Successfully");
    Con.close();

我知道准备好的语句不需要特殊字符处理。但是有时它也发生在准备好的语句中。因此，请尝试此操作，并让我知道问题是否已解决

我希望它能帮助您谢谢