如何选择每个唯一值之一？

Question

How do I get only 1 of each value that I'm searching for? This is what I have so far ...

    public String getRevisionsLog(String revName) {
    try {
        String txt = "\t\t\t\t\t\t\t#e---===Revision Logs===---#n\r\n";
        Connection con = DatabaseConnection.getConnection();
        PreparedStatement ps = con.prepareStatement("SELECT revision FROM revisions_log WHERE revisionName = ? ORDER BY REVISION");
        ps.setString(1,  revName);
        ResultSet rs = ps.executeQuery();
        while (rs.next()) {
            txt += rs.getString("revision") + "\r\n";
        }
        ps.close();
        rs.close();
        return txt;
    } catch (Exception e) {

    }
    return "No logs were found!";
}

So far in my database I have rows of values that have a revision value of 1 and 1.1. I want to retrieve those revision numbers, but only once of each. If I have for say ...

1, 1, 1, 1.1, 1.1, 1.1

I only want to retrieve 1 and 1.1, and not all the instances of 1.

Answer 1

使用DISTINCT关键字：

    PreparedStatement ps = con.prepareStatement("SELECT DISTINCT revision FROM revisions_log WHERE revisionName = ? ORDER BY REVISION");