php - MYSQL比较语句!比较语句不起作用

Question

我创建了一个包含三个表的数据库。我有一个表“字段”，其中包含 1-5 的 id_field 和一个包含开始时间和结束时间的表名称槽。当我想显示所有可用字段时，时间没问题，但当我想显示 id 值为 1 的字段时，仍然显示所有字段!!!!!!

这是我的代码:

echo("<select name='selSlot'>");
$mysql_link = mysql_connect("localhost","root","*********");
$db_select = mysql_select_db("nuevo", $mysql_link);
$query = "SELECT * FROM field WHERE id_field = 1 CROSS JOIN slot WHERE (id_field,id_slot) ".
"NOT IN(Select field_slot,res_slot From reservation WHERE res_date = '"
     .$today['year']."-".$today['mon']."-".$today['mday']."') ORDER by id_field,id_slot";
$result = mysql_query($query)
    or die ("Query '$query' failed with error message: " . mysql_error ());
$row = mysql_fetch_assoc($result);
echo "apoel";
while ($row) {
    echo("<option value='" .$row['id_field'].",".$row['id_slot']."'>".$row['description'].
        " ".$row['start_time']."-".$row['end_time']." </option>");
    $row = mysql_fetch_assoc($result);
}
echo("</select>");

我不知道为什么它不只向我显示 id 为 1 的字段，并且仍然向我显示所有字段!!!!

Answer 1

您的查询有两个 WHERE 子句:

.... WHERE id_field = 1   CROSS JOIN slot    WHERE ...

它应该会导致数据库错误。正确的语法是:

SELECT * 
FROM field 
    CROSS JOIN slot
WHERE id_field = 1 
  AND  (id_field,id_slot)
...