PHP meets MySQL
Address Book ExampleLet us create a rather simple, one table database containing names, addresses, phone numbers, etc. Then we will create a PHP site that interfaces with this database. The site will have two pages, the first will have a list of people in the database. The second will be shown after the user selects a person from the list and will display more information about the selected person.
In the test database, use the Create new table area to make a new table. Give it a name. We are all using the same database, so incorporate your name into the table name to prevent conflicts. Enter the number of fields. Mine will have 8 (id, first name, last name, email, office phone, home phone, department, office location).
Possible design of an address book
The ID FieldMost database tables should have an primary key a field (or fields) that can uniquely identify each record in the table. In this case we have chosen the PersonID to serve as the tables ID. We checked the radio button (first in the row) to indicate that it is a primary key. We chose the type to be CHAR which means that it can include letters (unlike a number) and must be of fixed length (unlike a varchar).
UniqueThe third column of radio buttons is labeled Unique.If a field is marked as unique, that means no two records in the table can have the same value for that field. Such a field is a candidate key that is, it could be used as the primary key but some other choice was made. In Banner a person can be identifies by a PIDM, a La Salle ID and a Social Security Number. One will serve as the primary key and the other should be marked as unique. There are no unique fields in our address book example (apart from the primary key)
IndexThe second column is marked Index. The usual meaning of Index is that you might want to sort on this field. If you indicate that you might want to sort on a field, the DBMS can do some of the work on this task ahead of time, so that it goes faster when requested. (Im not sure why unique and index are radio buttons something may be unique and a desirable field for sorting. ???)I selected index on the LastName field.
Field LengthsTry to choose field lengths that are long enough to accommodate the data you anticipate being entered, but that would rule out bad data being entered. A lot of the decisions that go into database design are about data integrity making sure that the data that gets in there is at least of the correct format.
Phone Numbers?Certain questions arise concerning phone numbers. Are they really numbers? Does one add or subtract them? If they are stored as text (CHAR or VARCHAR), should one store the formatting. Does one store 2155551234?Or does one store (215) 555-1234?
NULL or NOT NULLOne more decision regarding the fields in the table is whether or not a NULL value is allowed for the field. For the field designated as a primary key, the answer is a resounding NO. Since we are interested in integrity, forcing someone to enter data because the field is NOT NULL might make it more likely that they enter bad data. It is not always just a question of whether or not a field should have a value but a practical one of whether the data-entry person will know it. Is it meaningful to have the record with this field NULL?
Click on Save
In the table below, I allowed a lot of fields to be NULL, I didnt want to eliminate a record because any one piece of information is missing. If you are unhappy with your design decisions, you can click on the pencil icon for a field which will give you the option to edit the design.
Should you decide to collect more data about a person, you can add fields.
To start entering data, click on the Insert button.
Enter the values for your record in the Value column Make sure to put data in the Value column, the function column can throw one off at first. Also a little weird is this second record that gets ignored.
Click Go to enter the record, make your radio button choice depending on whether you have more data to enter or not.
As with any database action, it can be achieved using a SQL statement, which the interface shows you. This can be useful later on if you are designing an interface for data entry. Again it even provides the PHP.
View records, click on the table button on left, and then on Browse button at top.
Start two pages, one for the user to choose a name and the second to handle the request. Look ma, Im trying to be XHTML compliant.
Set some Page Properties, the Title, and then insert a form on the first page.
Choose an action and a method for the form. Well try GET this time. The form will have a drop-down list of names. The values will be the IDS. Thus the use of GET may be a security issue. If you think that your Ids should be kept more private, use POST.
Add a menu/list to the page. Give it a name.
To center the menu, go to code, place tags around the select tags and set the divs align attribute to center
Let us add one option to remind ourselves what the HTML for an option looks like.
Turn that into a comment, we want our options to come from the database.
Start a PHP code block with the select tags.
Add a statement to aid in debugging.
Assign some database related variables
Use the function for connecting to MySQL.die(): is a function that will allow you (possibly) to display a message and then get out of the script. With some errors one might desire the script to continue, with others one just wants to get out of the script. The die() function is used in the latter case.
Use the function for selecting the databaseIn the database select function, the database connection variable is an optional parameter. (You might need it if you were connecting to multiple databases.)
Assign to the $sql variable a string containing the SQL query and then use the function to execute the query. Remember the pma interface would provide you with the php for various queries that were performed on the database through the interface. So the assignment statement could be a copy/paste in some circumstances.
Loop through the query results and print out the result into HTML option tags. Note that the harder (less familiar) part here is the while loop with its row array and mysql_fetch_array function. However, it occurs often and is usually the same thing each time.
Result of records coming from database and being placed into options of a drop-down list (menu)
Insert a button below the drop-down list
Give it a name, a label and an action.
In the handler file, set up page properties, insert a header
Result of header tag insert.
Start a PHP block with the tags
Copy the database related code from the previous file
Edit the query to select data corresponding to the person chosen
Return to AddressBook, add a target to the form
Handler does not replace origin
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