PHP fSQL Tutorial

This tutorial is designed to give a brief overview of the PHP fSQL API since version 1.2. The syntax and function of the SQL queries understood by fSQL will be addressed in another tutorial.

I. The Basics

Every script that wishes to load fSQL needs to only include one file, the fSQL.php located in the distribution. If fSQL.php is in the same directory as the script using it, this is all you need:


Once the file is included, there is only one class you need for all of your SQL needs: fSQLEnvironment. This contains information on the different databases in the program and their location on the file system. fSQLEnvironment is a simple API that is very similar to the PHP mysql API in almost every way. For example, fSQLEnvironment's fetch_assoc() is modeled directly after mysql_fetch_assoc() so if you're having trouble understanding fSQL's documentation, the PHP mysql API could also help you understand what each function does.

To create a new fSQLEnvironment class, it has a simple constructor with no parameters:

$fsql = new fSQLEnvironment;

II. Defining Databases

Databases in fSQL are directories in the file system with an associated name given to them. To define one:

$fsql->define_db("mydb", "/path/to/db");

The first parameter is the database name and the second is the path to that database. This tells the environment that the database to be called "mydb" will be located in the directory /path/to/db on the file system. In other words, all table information and data for "mydb" should be loaded from and stored to the directory /path/to/db. If the supplied path does not exist, fSQL will attempt to create it and set the appropriate permissions.

As of PHP fSQL v1.2, fSQL allows you have multiple databases defined for fSQL. For example, one could define several databases like so:

$fsql->define_db("db1", "/path/to/db1");
$fsql->define_db("db2", "/path/to/db2");
$fsql->define_db("db3", "/path/to/db3");

To select which database is to be the default when using queries and other function calls, use the select_db() function:


This function is the equivalent to the "USE `db2`" query. You should always select a default database before using any other functions in fSQLEnvironment.

III. Data Definition and Manipulation

From here on out, the most important method for dealing with the databases' data is the query() method. The query method takes one parameter and that is the string fSQL query to execute. The simplest form is data definition and manipulation performs just the query and returns either a true value on sucess or a false value on failure.

$fsql->query("CREATE TABLE example(
   name VARCHAR(30), 
   age INT,
)") or die($fsql->error());

The other types of queries worth mentioning: data manipulation (like INSERT, UPDATE, etc). On these queries, the method affected_rows() returns the number of rows added or modified by the last data manipulation query. For example:

$fsql->query("DELETE FROM example WHERE id < 5")
  or die("DELETE failed: ".$fsql->error());
echo "Deleted Rows: ".$fsql->affected_rows();

IV. Data Selection

Executing data retrieval queries like SELECT are also performed using the query() method. Except on data retrieval queries, the query method returns a handle to a result set which can be iterated through row by row using the fetch methods. Below we see an example.

$results = $fsql->query("SELECT id, name FROM example WHERE age > 30")
  or die("SELECT failed: ".$fsql->error());
while($row = $fsql->fetch_array($results))
	echo $row['id']." ".$row['name']."\r\n";

fetch_array($results) returns the next row in the result set until the last row has passed and then it returns NULL to stop the loop.

There are several ways to iterate through a result set:

  1. Return the row as an associative array using the names/aliases of the columns as the row's keys:
    • $fsql->fetch_array($results)
    • $fsql->fetch_array($results, FSQL_ASSOC)
    • $fsql->fetch_assoc($results)
  2. Returns the row as a normal array with integer indexes:
    • $fsql->fetch_row($results)
    • $fsql->fetch_array($results, FSQL_NUM)
  3. Returns the row with both column name keys and integer keys:
    • $fsql->fetch_both($results)
    • $fsql->fetch_array($results, FSQL_BOTH)
  4. Returns the row as "class-less object" using the names/aliases of the columns as the object's member variables:
    • $fsql->fetch_object($results)

Other result set methods of interest: