如果我强制使用主索引进行查询,为什么在选择不同的列时,结果的时间会有很大差异?查询1MySQL [x]> explain select-------+---------+---------+------+---------+----------+-------+查询2
select * from Test
isset($_POST['username']));
$password = mysql_real_escape_string($password);
$query = mysql_query ("SELECT * FROM tb_funcionario WHERE username='$username' and password='$password'
execution time of 30 seconds exceeded in D:\xampp\htdocs\index.php on line 15while($topic = mysql_fetch_array(mysql_query("SELECT `name`, `post_count` FROM `topics`))){
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