How to get the return with executeQuery() in Java?

问题

I have this code;

String sql = "UPDATE Players SET Losses=Losses+1 WHERE UUID='" + p.getUniqueId() + "';"; 
stmt.executeUpdate(sql);

How can I get the current Losses for a specific Player p?

回答1:

You can get the losses like the following. Seems really trivial, guess you are an absolute beginner.

String sql = "SELECT Losses FROM Players WHERE UUID='" + p.getUniqueId() + "';"; 
ResultSet rs = stmt.executeQuery(sql);
int losses = -1;
if(rs.next()) {
    losses = rs.getInt("Losses");
}

回答2:

SELECT query will return it, but what's your real question?

String sql ="SELECT column_name,column_name FROM table_name WHERE column_name ="" ;";

回答3:

I would use a Select for Update, and something like this -

String query = "SELECT Losses FROM Players FOR UPDATE "
               + "Players SET Losses=Losses+1 WHERE UUID=?";
ps = conn.prepareStatement(query,
                       ResultSet.TYPE_FORWARD_ONLY,
                       ResultSet.CONCUR_UPDATABLE);
ps.setString(1, p.getUniqueId());
ResultSet rs = ps.executeQuery();
int losses = 0;
if (rs.next()) {
  losses = rs.getInt("Losses");
}

回答4:

You'd have to make a SELECT statement. Like SELECT losses FROM Players WHERE UUID='"+p.getUniqueId()+"';"; Then use Statement's executeQuery() which returns a ResultSet. You can use an iterator to extract the data from the ResultSet object.

来源：https://stackoverflow.com/questions/23986348/how-to-get-the-return-with-executequery-in-java