You need to store multiple answers from one form question in a single database field.
Set up your multi-input form fields to pass their values as an array by adding opening and closing bracket characters to the field name, like this:
<input type="checkbox" name="favcolors" value="Red">Red
Then use PHP's built-in implode( ) function to convert the array to a string separated by a unique character before storing the string in a single database field. In this Recipe, I'll use the pipe character (|) to separate unique values in the array-turned-string:
$favcolors_imp = implode("|",$favcolors);
Then you can insert the string $favcolors_imp into a text or varchar field in your SQL database.
If you need to convert the string back to an array, use the PHP explode function:
$favcolors_exp = explode("|",$favcolors_imp);
HTML provides two form elements that allow users to select multiple choices: the checklist created with the input type="checkbox" tag shown above, and the multi-option select list created with this code:
<select name="favcolors" size="10" multiple> <option value="Green" label=" Green ">Green</option> <option value="Black" label=" Black ">Black</option> <option value="Brown" label="Brown">Brown</option> </select>
The rendered versions of each type of list are shown in Figure 7-5.
Figure 7-5. What's your favorite color? Checkboxes and multi-option select lists both let users choose more than one answer to a form question
The array-to-string-to-array process works with both types of form elements provided the value of the name attribute has  at the end. Without the brackets, only the last value selected in the form ("Brown" in Figure 7-5) gets assigned to the $favcolors variable that PHP creates from the POST or GET arguments sent to it from the form. When the array gets imploded into a pipe-delimited string, then all three values can be stored in the database, as Green|Black|Brown.
Finally, a note about searching for a single value in database fields containing multiple valueswhich at first glance might seem more complicated than individual values each stored in their own field. Fortunately, SQL provides some syntax for combining searches to find unique matches:
SELECT * FROM my_table WHERE (favcolor LIKE '%Brown|%' OR favcolor LIKE '%|Brown' OR favcolor='Brown')
In this query, the search conditions enclosed in parentheses starting after WHERE show three possible permutations of the favorite color "Brown" stored in a field with other favorite color choices or by itself. Combining the LIKE operator with the wildcard percent sign (%) matches "Brown" at the beginning, middle, or end of a string of multiple favorite color choices, while favcolor='Brown' matches records for form respondents who chose "Brown" as their only favorite color.