PHP Quick Reference Cheat Sheet

A Programming › PHP cheat sheet in English by damachan

Quick Reference for useful and basic PHP

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PRs

HTTP Requests

`$_GET`	Access URL parameters.
`$_POST`	Access POST request body content.
`$_SERVER['php_self']`	Current php document url.

Built-in Functions

`include("x.php")`	Includes the PHP file "x.php".
`echo "<content>"`	Renders `<content>` on the page on load
`die( "message" )`	Exits the script, with a message.
`isset($a)`	Returns `true` if `$a` is not `NULL`
`isset($a, $b)`	Returns `true` if `$a` and `$b` is not `NULL`
`print_r($x)`	Prints readable information of `$x`
`empty($x)`	Checks if `$x` is empty or `false`
`trim($x)`	Removes leading and trailing whitespaces from `$x`

PHP MS SQL DLL Functions

`sqlsrv_connect`	Connect to Microsoft SQL Server db.
`sqlsrv_query`	Prepares and executes a query.
`sqlsrv_free_stmt`	Frees resources for the statement.
`sqlsrv_close`	Closes the SQL connection.
`sqlsrv_fetch_array`	Returns a row as an array.
`sqlsrv_next_result`	Move to the next result of the statement.
`sqlsrv_errors`	Returns error and warning information.

Example Form Loading

<?php
    // Get the parameter: "Fruit" from the URL query string.
    // Eg. https://example.php/?Fruit=Apple

    $Fruit = $GET['Fruit'];
?>
// Render the variable $Fruit in the HTML
<div>
    <?php echo $Fruit; ?>
</div>

Apple

Example SQL Query Insert

<?php
    $Name = "John Doe";
    $Age = 25;

    $db_server = "<server_hostname>"; 
    $db_username = "<database_username>";
    $db_password = "<database_password>";
    $db_database = "<database_name>";
    $connectionInfo = array("Database"=>$db_database, "UID"=>$db_username, "PWD"=>$db_password);
    $conn = sqlsrv_connect($db_server, $connectionInfo);

    $tsql = "INSERT INTO dbo.Customers ( Name, Age ) VALUES";
    // Append more string literals to the variable $tsql to form the full query
    $tsql .= "('".$Name."', '".$Age."')";

    $stmt = sqlsrv_query($conn, $tsql);

    // Free statement and connection resources.
    sqlsrv_free_stmt($stmt);
    sqlsrv_close($conn);
?>

Basic Syntax

`$variable = value`	Creates a variable, can be of any type.
`"string literal"`	A literal string
`// comment`	Comments will not execute.
`"x"."y"`	Concatenates `"x"` and `"y"`, resulting in `"xy"`

Flow Control

`if (x) {y} else if (a) {b} else {z}`	Conditional code block, if `x` is `true`, run `y`. Otherwise, if `a` is `true`, run `b`. Otherwise, run `z`
`do {x} while (y)`	A `do ... while` loop. Executes `x` as long as `y` is `true`
`while(x) {y}`	A `while` loop. Executes `y` as long as `x` is `true`

Comparison Operators

`!$x`	Returns `true` if `$x` is `false`
`$x == $y`	Returns `true` if `$x` matches `$y` in value
`$x === $y`	Returns `true` if `$x` matches `$y` in value and type
`$x != $y`	Returns `true` if `$x` does not match `$y` in value
`$x !== $y`	Returns `true` if `$x` does not match `$y` in value or type
`$x <> $y`	Same as `$x != $y`
`$x && $y`	Returns `true` if both `$x` and `$y` is `true`
`$x \|\| $y`	Returns `true` if either `$x` or `$y` is `true`
`$x > $y`	Returns `true` if `$x` is greater than `$y`
`$x < $y`	Returns `true` if `$x` is less than `$y`
`$x >= $y`	Returns `true` if `$x` is greater than or equal to `$y`
`$x <= $y`	Returns `true` if `$x` is less than or equal to `$y`

Example Form Submission

<?php
    // Check if the request is a HTTP POST request. If it is, $_POST will not be empty.
    if ($_POST) {
        $Fruit = $_POST['Fruit'];
        // Fruit will have the value from the input element with the property: name="fruit" upon submission.
    }
?>

<form method="post" action="<?=$_SERVER['php_self']?>">
    <input type="text" name="fruit" id="fruit_id" />
    <input type="submit" value="Submit" />
</form>

Example SQL Query Select

<?php
    $db_server = "<server_hostname>";
    $db_username = "<database_username>";
    $db_password = "<database_password>";
    $db_database = "<database_name>";
    $connectionInfo = array("Database"=>$db_database, "UID"=>$db_username, "PWD"=>$db_password);
    $conn = sqlsrv_connect($db_server, $connectionInfo);

    $tsql = "SELECT FirstName, LastName FROM dbo.Customers";
    $stmt = sqlsrv_query($conn, $tsql);

    if( $stmt === false) {
        die( print_r( sqlsrv_errors(), true) );
    }

    while( $row = sqlsrv_fetch_array( $stmt, SQLSRV_FETCH_ASSOC) ) {
          echo $row['LastName'].", ".$row['FirstName']."<br />";
    }

    // Free statement and connection resources.
    sqlsrv_free_stmt($stmt);
    sqlsrv_close($conn);
?>

Doe, John
Sue, Mary

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