Array functions
srand() -- Seeds the random number generator. Usage: srand((double)microtime()*1000000);

shuffle() is dependent on the random number generator. It shuffles the indeces in an array (the argument).
    asort(), arsort, ksort, krsort are ways of rearranging the elements of an array (numerical and alphabetical sorting on either keys or values (asort). r signifies _reverse_.

array_pop() -- takes an element off of the end of an array.
shift() -- takes an element off of the beginning of an array.
    Usage: $el = array_pop($my_array); // my_array is one element shorter
String functions
trim() -- removes "white space" (space, tabs, endlines) from beginning and end of a string. "shrink wraps" alphanumeric characters.

ereg() is a pattern detection function that returns a boolean value (true if it matches a given substring inside the target string).
    Usage: $long = "this is a long string";
    if(ereg("this",$long)) print("yes i found it");
MySQL - related functions and concepts
get_magic_quotes_gpc() -- magic quotes are intended to prevent you from inserting certain characters into MySQL databases (these are: ' " \ NUL)

addslashes() -- to be used (if the get_magic_quotes_gpc() returns false) to return a "safe" string. removeslashes() -- reverses the string returned by addslashes to the state of the original argument to addslashes().
    To move a database from one server to another, you can either use a tool such as PHP_MySQL_Admin to export the database in various formats, or you can use the tool mysqldump, which will give you a text file that contains SQL commands useful for reinitializing the database. Once you have redirected the output of mysqldump to a file (mysqladmin -u php -p > ~/web/mySchema.txt) you can compress it using gzip (gzip ~/web/mySchema.txt). Once you have this file compressed, it can be downloaded via HTTP or transferred to another server via SSH and/or SFTP. (sftp me@my.com
    sftp> put mySchema.txt.gz)