Connecting PHP and MYSQL Formula Sheet

Core Functions and Parameters

Below is a quick reference table of key PHP database connection functions, parameter structures, and their return behaviors.

Function Name	Syntax and Parameters	Return Value	Description
mysqli_connect	mysqli_connect(host, username, password, dbname)	Connection object (or false on failure)	Establishes a connection to the MySQL server and selects the specified database.
mysqli_query	mysqli_query(connection_link, query_string)	Result object (for SELECT) or boolean (for INSERT/UPDATE/DELETE)	Sends an SQL query to the database server for execution.
mysqli_close	mysqli_close(connection_link)	Boolean (true on success, false on failure)	Closes an open connection link and releases system resources.
mysqli_connect_error	mysqli_connect_error()	String describing the error (or null)	Returns a textual explanation of the last connection failure.
mysqli_num_rows	mysqli_num_rows(result_object)	Integer (number of rows)	Retrieves the total number of records returned by a SELECT query.
mysqli_fetch_array	mysqli_fetch_array(result_object)	Array representing the row (or false if none)	Fetches the next row of data as an associative or numeric array.

Server Host: Typically 'localhost' when executing scripts on the same server where the MySQL database resides.
Default Port: MySQL server usually listens on port 3306. This is handled internally unless specified otherwise in advanced parameters.
PHP Version Minimum: PHP version 5.0.0 or higher is required to use the mysqli extensions natively.