db.php Documentation

Overview

The db.php file is a PHP script that handles database operations such as connection, query execution, and data retrieval. It also includes utility functions for handling HTTP requests and responses.

Database Connection

The script connects to a MySQL database using the mysqli extension. The connection parameters are retrieved from a properties.php file.

HTTP Request Handling

The script handles HTTP POST and PUT requests with a content type other than application/x-www-form-urlencoded. The request body is parsed as JSON and the parameters are added to the $_POST superglobal.

Database Query Functions

The script provides several functions for executing SQL queries and retrieving data:

• query($sql, $show_query = false): Executes an SQL query and returns the result. If $show_query is true, the query is also outputted for debugging purposes.
• select($sql, $show_query = false): Executes an SQL SELECT query and returns the result rows as an associative array.
• scalar($sql, $show_query = false): Executes an SQL SELECT query and returns the first column of the first row.
• selectMapList($sql, $column, $show_query = false): Executes an SQL SELECT query and returns the result rows as an associative array, using the specified column as the key.
• selectList($sql, $show_query = false): Executes an SQL SELECT query and returns the first column of the result rows as an array.
• selectRow($sql, $show_query = false): Executes an SQL SELECT query and returns the first row as an associative array.

Error Handling

The script includes a error($error_message) function that sends an HTTP 500 response with a JSON body containing the error message. If the DEBUG constant is true, the function also includes a stack trace in the response.

Utility Functions

The script includes several utility functions for handling arrays, strings, and HTTP requests. These include functions for encoding and decoding JSON, generating random IDs, and retrieving request parameters.

Constants

The script uses several constants for configuration:

• DEBUG: If true, the script includes a stack trace in error responses.
• MYSQLI_OPT_INT_AND_FLOAT_NATIVE: This constant is used to configure the mysqli extension to return integer and float columns as native PHP types.

Global Variables

The script uses several global variables:

• $mysql_conn: The mysqli connection object.
• $host_name: The host name for the database connection.
• $GLOBALS[conn]: A reference to the mysqli connection object.
• $GLOBALS["params"]: An associative array of request parameters.