sql server - t-sql: incompatibility between built-in boolean functions -


why built-in boolean functions behaves differently on null input ? example - query:

select 'isdate(null)'                 function_call,          isdate(null) result union select 'isnumeric(null)'              function_call,          isnumeric(null) result union select 'is_member(null)'              function_call,          is_member(null) result union select 'is_srvrolemember(null, null)' function_call,          is_srvrolemember(null, null) result

gives us:

function_call                result ---------------------------- ----------- isdate(null)                 0 isnumeric(null)              0 is_member(null)              null is_srvrolemember(null, null) null

so seems isdate, isnumeric behaves according boolean logic, is_member,is_srvrolemember - behaves according three valued logic. shouldn't boolean functions behave same on null input ? ansi sql standard says ?

thanks

i don't find odd these security functions (is_srvrolemember) behave differently system/datatype functions (isnumeric) since these security functions queries , results can change depending upon querying. meanings of return values, including nulls, spelled out of these in msdn documentation.

more concretely, arguments isnumeric , isdate, can test ahead of time if argument null or not, i'm not sure returning null necessary, or has practicality.

for arguments security functions, may have non-null arguments, functions have been built in helpful manner return null in cases arguments aren't valid, not found, or don't have permissions know answer.

much of can seen subjective, have voted close question, interesting may be.


Comments

Post a Comment

Popular posts from this blog

Why does Ruby on Rails generate add a blank line to the end of a file? -

running rails generate controller foo home results in: class foocontroller < application controller def home end end (there's nothing on line in actual file, blank line) is there purpose blank line? it's common use newline indicate end of line, last line. many editors (like vi, use) add in newline silently. consensus text files (especially in unix world) should end in newline, , there have been problems historically if wasn't present. why should text files end newline? the tool used count lines in file "wc" counts newlines in file, without trailing newline show 3 instead of 4. it improves readability of templates used in generator. consider: https://github.com/rails/rails/blob/master/railties/lib/rails/generators/rails/controller/templates/controller.rb to remove trailing newline, template have last line of: end<% end -%> instead of: end <% end -%> that seems less readable me. the discussion below refers
Read more

keyboard - Smiles and long press feature in Android -

i've created android keyboard. how add features inserting smilies, , using long keypresses display symbols? to create long-press behavior allows select several options pop-up menu, follow guide (specifically pop-up menu section): http://developer.android.com/guide/topics/ui/menus.html smileys (also known emoticons) combination of keys, understood programs , parsed same way. have do, when clicks smiley face on keyboard, simulate pressing of key combination matching emoticon. example, when clicks smiley, should simulate key presses ':' , ')' :). here's list of emoticons: http://en.wikipedia.org/wiki/list_of_emoticons
Read more

node.js - Bad Request - node js ajax post -

i'm using express 3.0 , node v0.11.0. have button submits form , i'm using ajax post data json object node server. client code is: $('#contact').submit(function(e) { console.log('submit called'); var formdata = json.stringify($('form').serializeobject()); console.log(formdata); $.ajax({ url: "http://localhost:3000/savedata/", type: "post", datatype: 'json', data: {objectdata: formdata}, contenttype: "application/json", complete: function() { console.log('process complete'); }, success: function(data) { console.log('process sucess'); }, error: function() { console.log('process error'); }, }); return false; }); then on server: var express = require('express'); var app = express(); app.set('views', __dirname + '/views'); app.set('view engine', 'jade'); app.use(express.bodyparser());
Read more