Tips to write fields of a database table into a select field.
Sometimes, when building a form, the programmer needs to have a select field which values are obtained from a table in a database. The dynamical building of this field can easily be done using a simple PHP function. We can take for example a table with countries. The function we will design will be able to build the select field.
It might be a good idea to have a table containing all the countries and use it to build a list of country by consulting this table, allowing the user to choose among the countries available.
The table "country" might contain the following data:
| id_country |
name_country |
| AD |
Andorra |
| AE | United Arab Emirates |
| AF | Afganistan |
| AG | Antigua and Barbuda |
| AI | Anguilla |
| AL |
Albania |
| AM |
Armenia |
| AN |
Netherlands Antilles |
| AO |
Angola |
| AQ |
Antarctica |
| AR |
Argentina |
| AS |
American Samoa |
| AT |
Austria |
| [...] |
[...] |
The following HTML code would be the one used, if we wouldn't have the function:
To fill a select field with the 247 existing countries might take a lot of time to write the code!
Function dynamic_countries()
Now let's see how we would do to create a function that would present all the countries after consulting them into a table.
The following parameters will be passed to the function:
- sql_string: The query that extracts the data to fill the select field. The SQL sentence should be like "select id_country, name_country from country order by id_country". The first extracted column should be the "id" of the country, the second, should be the name of the country.
- default: This parameter receives the selected by default value of the select field. If you want "Netherlands Antilles" to be selected by default, this parameter should have the value: "AN".
- field_name: This is the name of the select field.
So here is the PHP code for the function:
To be exectued as is, this function requires a connection to be openned.
Note also that this function can easily be adapted to build select fields of any kind as long as the query respects the previous rules: first field should be the id and the second the name.
History
2008-09-24: First version
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