How to check for data in a Mysql database using PHP? [closed]

Closed. This question needs to be more focused. It is not currently accepting answers.

---

Want to improve this question? Update the question so it focuses on one problem only by editing this post.

Closed 8 years ago.

开发者_Go百科 Improve this question

I was wondering how can you check to see if certain data is present in a database and if so display it on the web page and if not don't display it using PHP.

---

You select the data and you can use mysql_num_rows() to check how many rows were returned.

If no rows are returned, you can do something else.

Rough unsafe example

$query = mysql_query("SELECT * FROM users WHERE id = 20");
$num = mysql_num_rows($query);

if($num > 0)
{
    // Stuff to do when you find the items
}
else
{
    // No items found
}

---

That's a pretty involved question. It requires you to connect to your database mysql_connect(), query it mysql_query(), and pour out any results from the query mysql_fetch_object().

---

Using the PHP MySQL interface functions, you run a SQL SELECT query that will retrieve the data you are looking for. Using a PHP control structure such as if, you then conditionally display the data, or not, depending on its existence or lack thereof.