Top "Exists" questions

Check if method exists in the same class

So, method_exists() requires an object to see if a method exists. But I want to know if a method …

php class methods exists

Mongo: find items that don't have a certain field

How to search for documents in a collection that are missing a certain field in MongoDB?

mongodb null exists

How to check if a file exists on a server using c# and the WebClient class

In my application I use the WebClient class to download files from a Webserver by simply calling the DownloadFile method. …

c# http file webclient exists

SQL "if exists..." dynamic query

Suppose I have a query stored in a variable like this (it's actually dynamically populated and more complex, but this …

sql sql-server exists

Check if table exists with if statement in C#?

I try to put up an if statement to check if a table is already created. I only want to …

c# datagridview datatable exists readxml

How to check if a variable exists with a value without "undefined local variable or method"?

This is a common pattern: If a variable doesn't exist I get an undefined local variable or method error. The …

ruby-on-rails ruby variables undefined exists

NodeJS + Mongo: Insert if not exists, otherwise - update

I have an object in my mongodb collection. Its schema is: { "instruments": ["A", "B", "C"], "_id": { "$oid": "508510cd6461cc5f61000001" } } …

node.js mongodb insert exists updates

Check if extended property description already exists before adding

So, I have a script that adds extended properties, some describing a table, some describing a column. How can I …

sql sql-server exists extended-properties database-table

How can I test if a filename matching a pattern exists in Perl?

Can I do something like this in Perl? Meaning pattern match on a file name and check whether it exists. …

perl file match exists glob

Check if a table contains a row with a specific column value

In T-SQL syntax, how could I check to see if a table has a row with a a column matching …

tsql sql-server-2012 exists