Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>In general one should sanitize first - "for your protection, and theirs." This includes stripping out any invalid characters (character coding sensitive, of course). If a field should only contain characters and spaces, then strip out anything that isn't that first.</p> <p>With that done, you then validate the results - is the name already used (for unique fields), is it the right size, is it not blank?</p> <p>The reason you give is precisely the right one - to maximize the user experience. Don't confuse the user, if you can avoid it. This helps protect from dumb copy &amp; paste behavior, but you have to be careful - if I want my name recorded as "Ke$h@", I may or may not be ok with changing it to "Keh".</p> <p>Secondly, it is also to prevent bugs. </p> <p>What happens when you want to create usernames that don't allow special characters? If I enter "Brian", and your system rejects it as the name us already in use, then I submit "Brian$"? First you validate it, and it is not in use, then you strip special characters and you are left with "Brian". Uh oh - now you either have to validate AGAIN, or you'll get a weird error that either account creation failed (if your database is set to require unique usernames, for instance), or worse it will succeed and over-writing/corruption occurs to user user accounts.</p> <p>Another example is minimum field lengths: if you require a name be at least 3 letters long and only accept letters, and I enter "no" you'd reject it; but if I enter "no@#$%" you would might say it was valid (long enough), sanitize it, and now it isn't valid anymore, etc.</p> <p>The easy way to avoid this is sanitize first, and then you don't have to double-think about validation.</p> <p>However, Niet was right about not encoding data before storage; it is generally much easier to setup output into HTML as being encoded when appropriate, then it is to remember to decode it when you just want the plain text (to entry into text boxes, JSON strings, etc). Most test cases you'll use won't include data with HTML entities, so its easy to introduce silly bugs that aren't easily caught.</p> <p>The big problem is that when such a bug is introduced, it can quickly lead to data corruption that is not easily solved. Example: you have plain text, output it to a text field incorrectly as html entities, the form gets submitted back and you re-encode it...every time it gets opened/resubmitted it gets re-encoded. With a busy site/form you could end up with thousands of differently encoded entries, with no clear way to determine what should and what was not intended to be HTML encoded.</p> <p>Protecting from injection is good, but HTML encoding isn't designed (and must not be relied upon) to do that.</p>
    singulars
    1. This table or related slice is empty.
    1. POwhich one should performe first ? sanitizing or validation
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USBrianH
    1. USBrianH
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COok, assume that you habe enterd Brian$, first saniteze that and the result will be Brian, and validate that and it's unique, ok youre know registered and you want to log in, you enter Brian and again in log in form i shoul sanitize the input? so if yeh i should out put hello Brian , and you would got confused becouse you entered Brian$
      singulars
      1. PO
      1. USnaazanin
    2. COYou should let the user know that you had to sanitize the input - I would even go as far as to suggest in a situation like this that you give an error to the user when he inputs that it is invalid.
      singulars
      1. PO
      1. USDeniz Zoeteman
    3. CO@naazanin I'd agree with gdscei, though generally I save such niceties to before-posting client-side form validation. There I am more gentle about prompting the user about invalid output, where on the server-side I'm more likely to chose one of two models: 1) make it work and don't bother the user if they don't have to know, or 2) reject invalid input and let the user figure out what to do. This will depend on your use case, and I can't offer a global suggestion. The more international your app will be, the more careful you'll need to be about forbidding potentially valid characters.
      singulars
      1. PO
      1. USBrianH
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload