当错误[重复]时，mysql是否将数据返回到php变量

Question

This question already has an answer here:

• How to check if a MySQL query using the legacy API was successful? 6 answers

so i created php variable contain mysql query inside , but is it will return data to the php variable when the table / column / data is not available ?

example :

 $a1='1';
$item1nanowr = mysql_query("SELECT item_name FROM item_info WHERE item_special_number = $a1 ");

now just imagine that item_name column not available , is it will return data ?

and if i put "or die" statement like this :

$item1nanowr = mysql_query("SELECT item_name FROM item_info WHERE item_special_number = $a1 ") or die("Coming Soon");

is it will return word Coming Soon ?

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Answer 1

or die() will run only if something goes wrong with the query. Several things could go wrong. Some of them are:

• The database table does not exist
• One of the specified columns does not exist
• There is a syntax error in the query
• The database is offline or the connection has been lost

So it will run on critical errors. It won't run if your table or a specific column is empty.

Also it is very important to stop using mysql_ functions!. The mysql extension is deprecated from PHP 5.5 and completely removed from PHP 7.

Use mysqli or PDO instead. You should also use Prepared Statements instead of directly interpolating variables in your query. More on Prepared Statements here