Common PHP/MySQL Procedures

[MeTi]

This is how I learned to do these things; works very well and all methods are very flexible.

CONNECTING TO DATABASE
----------------------------

PHP Code:
mysql_connect("localhost", "db_username", "db_pwd"); //Login as a database user. set this up in CPanel
mysql_select_db("db_name"); //select the database associated with the user



INSERTING INTO A DATABASE TABLE
-------------------------------------

PHP Code:
mysql_query("INSERT INTO table_name VALUES(NULL, '$first_field', '$second_field', '$etc')");

Only use that NULL if you have an auto_increment (like an 'id' field) or something.


MODIFYING A DATABASE TABLE
--------------------------------

PHP Code:
mysql_query("UPDATE table_name SET field_name='$variable',different_field='$anotheron e' WHERE id='$thisID' LIMIT 1");

You can modify the "WHERE" clause to fit any criteria you need, and the LIMIT to whatever you want.


RETRIEVING FROM A DATABASE TABLE
---------------------------------------
The more complex part of database interaction... we're also going to set up the variables to USE the values we retrieve in a list, etc.


PHP Code:
$results = mysql_query("SELECT * FROM table_name WHERE id='$variable' LIMIT 5"); //This gets the data we want

//Now we need to get and display the data, very simply.
//The $row variable is an array that holds each row's data through the while loop.
while ($row = mysql_fetch_array($results))
{
$showThis = $row['field_name'];
echo($showThis."<br>");
}
//Now, each time we go through a row in the database,
//(5 in this case, because of our LIMIT clause in the query),
//it shows the value of a table field named "field_name" then goes
//to another line for the next table row.


That was the most complex part of this actually simple process.


DELETING A ROW FROM A TABLE
---------------------------------

PHP Code:
mysql_query("DELETE FROM table_name WHERE id='$thisID' LIMIT 1");



CLOSING DATABASE CONNETION
---------------------------------

PHP Code:
mysql_close();