我想在不同的数据库表中搜索数据?
例如,我输入一个像'demo'这样的词,点击'search'按钮,然后从'product'表和'article'表中显示与'demo'词相关的数据。
那么,我该如何编写sql语句呢?
顺便说一句,我使用 PHP 和 Mysql。
您可以从查询开始,例如它不适合您,因为您没有显示任何表结构、列的信息。所以下面只是我的猜测
SELECT * FROM article a
INNER JOIN product p
ON p.id = a.product_id
WHERE
a.article LIKE "%demo%"
OR
p.title LIKE "%demo%";
你可以试试UNION ALL
SELECT * FROM article a
a.article LIKE "%demo%"
UNION ALL
SELECT * FROM product p
p.title LIKE "%demo%";
但请确保它们应具有相同的列数。在此处阅读有关 UNION的更多信息
下面是我给出的小代码,开始学习它是如何工作的
<?php
mysql_connect("localhost", "root", "") or die("Error connecting to database: ".mysql_error());
/*
localhost - it's location of the mysql server, usually localhost
root - your username
third is your password
if connection fails it will stop loading the page and display an error
*/
mysql_select_db("your_database") or die(mysql_error());
/* your_database is the name of database we've created */
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Search results</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link rel="stylesheet" type="text/css" href="style.css"/>
</head>
<body>
<?php
$query = $_GET['query'];
// gets value sent over search form and in your case it is demo
$min_length = 3;
// you can set minimum length of the query if you want
if(strlen($query) >= $min_length){ // if query length is more or equal minimum length then
$query = htmlspecialchars($query);
// changes characters used in html to their equivalents, for example: < to >
$query = mysql_real_escape_string($query);
// makes sure nobody uses SQL injection
$raw_results = mysql_query("SELECT * FROM article a INNER JOIN product p
ON p.id = a.product_id WHERE (`title` LIKE '%".$query."%') OR (`text` LIKE '%".$query."%')") or die(mysql_error());
// * means that it selects all fields, you can also write: `id`, `title`, `text`
// articles is the name of our table
// '%$query%' is what we're looking for, % means anything, for example if $query is Hello
// it will match "demo", "here demo", "demohere", if you want exact match use `title`='$query'
// or if you want to match just full word so "gogohello" is out use '% $query %' ...OR ... '$query %' ... OR ... '% $query'
if(mysql_num_rows($raw_results) > 0){ // if one or more rows are returned do following
while($results = mysql_fetch_array($raw_results)){
// $results = mysql_fetch_array($raw_results) puts data from database into array, while it's valid it does the loop
echo "<p><h3>".$results['title']."</h3>".$results['text']."</p>";
// posts results gotten from database(title and text) you can also show id ($results['id'])
}
}
else{ // if there is no matching rows do following
echo "No results";
}
}
else{ // if query length is less than minimum
echo "Minimum length is ".$min_length;
}
?>
</body>
</html>