Question

我有这段代码;

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

如何获取特定Losses的当前Player p？

Answer 1

SELECT查询将返回它，但你真正的问题是什么？

String sql =＆＃34; SELECT column_name，column_name FROM table_name WHERE column_name =＆＃34;＆＃34; ;＆＃34 ;;

Answer 2

我会使用Select for Update，类似这样的东西 -

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");
}

Answer 3

您可以获得如下所示的损失。看起来真是微不足道，猜猜你是一个绝对的初学者。

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");
}

Answer 4

您必须制作SELECT语句。就像选择SELECT FROM FROM WHERS UUID ='“+ p.getUniqueId（）+”';“; 然后使用Statement的executeQuery（）返回ResultSet。您可以使用迭代器从ResultSet对象中提取数据。

如何在Java中使用executeQuery（）获得返回？

4 个答案: