exists

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SQLAlchemy EXISTS queryset

I use only django framework with his ORM. And there is some code: User.objects.filter(username=\'test\').exists()[详细]

2023-04-02 06:10 分类：问答
T-SQL SELECT with child rows exists optimise

I\'m trying to optimise my query. Basically I have an Department table and a document table. Each document belongs to a department and each document can be a specific type.[详细]

2023-03-31 23:55 分类：问答
Perl LWP::Simple::getstore How to check if the file exists in destination directory

In my Perl script I am using LWP::Simple::getstore to retrieve an image and store as file. But before storing how to check if that f开发者_开发技巧ile already exists?[详细]

2023-03-29 10:03 分类：问答
In mysql, how to avoid selection if a table exists

Let\'s say I run the following query: CREATE TEMPORARY TABLE IF NOT EXISTS FISH SELECT \'a\'; it will create a temporary table with \'a\' in it. Now, if I run the query again, the tab开发者_如何学P[详细]

2023-03-29 02:39 分类：问答
Android: File.exists returns true when it should return false

I have a bizarre problem. I write a file to the SD card and then I remove the SD card. With the card removed, I then check for the existence of the file with File.exists.[详细]

2023-03-26 19:12 分类：问答
how to check if an object exists in an array which is found in a global class in C#

I am making a game which has a global (static) class called MedGameController. In my class I have two arrays of fifteen objects each which hold the logic for each players开发者_JS百科 units. In the ga[详细]

2023-03-25 05:36 分类：问答
DB2 for IBM iSeries: IF EXISTS statement syntax

I am familiar with Sybase which allows queries with format: IF EXISTS () THEN ... ELSE ... END IF (or very close).This a powerful statement that allows: \"if exists, then update, else insert\".[详细]

2023-03-24 15:35 分类：问答
Check if a div exists with jquery [duplicate]

This question already has answers here: Is there an "exists" function for jQuery? (47 answers)[详细]

2023-03-24 02:07 分类：问答
Only display a user-uploaded photo if it exists in rails

<%= image_tag message.photo.url(:small) %> I have paperclip installed and the above code displays an image that the user uploads which has been resized to :small (in this case 40x40px. How can[详细]

2023-03-23 00:14 分类：问答
JQuery: Check if element exists alongside '.remove()'

I know you can check if an element exists with $(\'di开发者_如何学Cv\').length, but when an element is destroyed using .remove(), .length still reports the div exists. How can I find whether or not it[详细]

2023-03-20 21:32 分类：问答