java - org.postgresql.util.PSQLException : ERROR: syntax error at or near "7"

Question

我正在尝试在我的应用程序中创建私有(private)聊天，但是当我尝试创建表时出现此错误:

org.postgresql.util.PSQLException: ERROR: syntax error at or near "7" Position: 14

代码:

 public static String checkIfChatExists(String code, String friend) throws SQLException {
        String i = LoginManager.checkCode(code);
        if(i.equals("code-not-exists")) {
            return "invalid-code";
        }

        ResultSet rs = conn.prepareStatement("SELECT * FROM pwchats").executeQuery();
        while (rs.next()) {
            if(rs.getString("user1").equals(i) && rs.getString("user2").equals(friend) || rs.getString("user1").equals(friend) && rs.getString("user2").equals(i)) {
                return "exists";
            }
        }
        PreparedStatement pre = conn.prepareStatement("INSERT INTO pwchats(user1, user2) VALUES(?, ?)");
        pre.setString(1, i);
        pre.setString(2, friend);
        pre.execute();
        PreparedStatement getChatId  = conn.prepareStatement("SELECT * FROM pwchats WHERE user1 = ? AND user2 = ?;");
        getChatId.setString(1, i);
        getChatId.setString(2, friend);
        ResultSet rss = getChatId.executeQuery();
        while (rss.next()) {
            PreparedStatement chat = conn.prepareStatement("CREATE TABLE " + rss.getInt("id") + "chat (username text NOT NULL, created_at timestamp with time zone NOT NULL DEFAULT now(), avatar text NOT NULL, message text NOT NULL, id serial NOT NULL);");
            chat.execute(); //ERROR
            return "done";
        }
        return "wat";
    }

Answer 1

您看到的错误可能来自那里:

preparedStatement chat = conn.prepareStatement("CREATE TABLE " + rss.getInt("id") + "chat (...);");

通常在 SQL 中，表名不能以数字开头。如果您要用双引号将表名引起来，Postgres 仍然允许这样做，但是每次查询时都需要双引号表名，这可能会很乏味。

一种解决方案是将数字放在表名称的末尾，例如:

preparedStatement chat = conn.prepareStatement("CREATE TABLE chat" + rss.getInt("id") + " (...);");

<强> Demo on DB Fiddle :

create table 7chat(x int);

ERROR:  syntax error at or near "7"LINE 1: create table 7chat(x int);                     ^

create table "7chat"(x int);
-- works

create table chat7(x int);
--works