JDBC更新查询错误 [英] JDBC Update query error

问题描述

我无法使用where子句在JDBC上执行更新查询.我想通过串联一些变量来执行查询.

I can't execute the update query on JDBC with where clause. I want to execute the query by concatenating some variables.

protected void updateEmail(String Email, String Username) {
    try {

        conn = DriverManager.getConnection("jdbc:mysql://localhost/project", "root", "");

        String query = "update access set email=" + Email + " where username=" + Username;

        Statement st = conn.createStatement();
        st.executeUpdate(query);

    } catch (SQLException ex) {
        System.out.println(ex);
    } finally {
        try {
            conn.close();
        } catch (SQLException ex) {

        }
    }
}

它说:

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'bhusal1' in 'where clause'

推荐答案

字符串应位于两个引号'name'之间，而不是必须使用

String should be between two quotes 'name' instead of your way you have to use PreparedStatement instead to avoid syntax error or SQL Injection :

String query = "update access set email=? where username=?";
PreparedStatement ps = con.prepareStatement(query);

ps.setString(1, email);
ps.setString(2, name);
ps.executeUpdate();

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