PHP connection database under IIS prompts mysql undefined function mysql_connect()_PHP tutorial

1.
Remove the ";" in front of the following parameters in PHP.ini:

Save the file and restart IIS
Specific instructions
Place ;extension=php_mysql.dll
Change to
extension=php_mysql.dll
extension_dir = " "
Change to
extension_dir = "ext/"
Then change libmysql.dll Copy it to system32 and then restart it
Test whether php mysql can connect
$link=mysql_connect( 'localhost ', 'root ', '123456 ');
if(!$link) echo "fail ";
else echo "success ";
mysql_close();
?>
2.
1.php_info() Check if there is mysql (search for the "mysql" keyword), if there may be a version compatibility issue
2. If you have not copied the libmysql.dll in the php file to x:windowssystem32, change the mysql module in php.ini Comment out extension=php_mysql.dll and restart apache. If it still doesn't work, try restarting the machine and test using the php_info() function.
Right-click My Computer->Properties->Advanced->Environment Variables->System Environment Variables
a. Select Path in "System Environment Variables" to highlight this line, and then Select "Edit" and add ";D:php" (the directory where php.exe is located) at the end of the variable value
b. "System Environment Variables"->"New"->Variable name "PHPRC"- >Variable value "D:php" (the directory where php.ini is located) ->
2. Check that the PhpIniDir setting in the httpd.conf file points to the directory of Php.
3. Try to change PhpIniDir="C:/Php" in httpd.conf to PhpIniDir="C:Php".