mysql如何使用Java中的executeQuery（）获取返回？

Question

我有这个密码

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

如何获取特定Player p的当前Losses

Answer 1

SELECT查询将返回它，但您真正的问题是什么

String sql=“选择column_name，column_name FROM table_name WHERE column_name=”“；”

Answer 2

你可以得到如下损失。看起来真的很琐碎，我猜你绝对是个初学者

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 3

我会使用Select进行更新，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 4

你必须做出选择声明。比如UUID='“+p.getUniqueId（）+”；"; 然后使用语句的executeQuery（）返回结果集。可以使用迭代器从ResultSet对象中提取数据