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How to check if a stored procedure exists before creating it
...a query.
Just copy everything after AS:
BEGIN
DECLARE @myvar INT
SELECT *
FROM mytable
WHERE @myvar ...
END
This code does exactly same things a stored proc would do, but is not stored on the database side.
That's much like what is called anonymous procedure in PL/SQL.
Up...
Show an image preview before upload
... code snippet in the HTML example below filters out images from the user's selection and renders selected files into multiple thumbnail previews:
function handleFileSelect(evt) {
var files = evt.target.files;
// Loop through the FileList and render image files as thumbnails.
fo...
When to use a View instead of a Table?
...
Oh there are many differences you will need to consider
Views for selection:
Views provide abstraction over tables. You can add/remove fields easily in a view without modifying your underlying schema
Views can model complex joins easily.
Views can hide database-specific stuff from you. E....
How to get database structure in MySQL via query
...CHEMA.TABLES table. It contains metadata about all your tables.
Example:
SELECT * FROM `INFORMATION_SCHEMA`.`TABLES`
WHERE TABLE_NAME LIKE 'table1'
The advantage of this over other methods is that you can easily use queries like the one above as subqueries in your other queries.
...
Could not instantiate class named MKMapView
... project to bring the project settings. Under Targets, click your project, select from the upper toolbar "Build Phases". Under "Link binary With Libraries" tab, you will see the list of frameworks included in your project. Click the "+" button and add MapKit library from the shown list to your proje...
How to set cursor position in EditText?
...
Where position is an int:
editText1.setSelection(position)
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Ignoring time zones altogether in Rails and PostgreSQL
...n parameter before being displayed to the client.
Example (in psql):
db=# SELECT timestamptz '2012-03-05 20:00+03';
timestamptz
------------------------
2012-03-05 18:00:00+01
What happened here?
I chose an arbitrary time zone offset +3 for the input literal. To Postgres, this is just one o...
How do I directly modify a Google Chrome Extension File? (.CRX)
... remove the _metadata folder.
From chrome://extensions in Developer mode select Load unpacked extension... and select your copied extension folder, if it contains a subfolder this is named by the version, select this version folder where there is a manifest file, this file is necessary for Chrome....
textarea's rows, and cols attribute in CSS
...you use "em" rather than "px" then you can specify the width and height in characters as you would with 'rows' and 'cols' attributes. Even works with IE6 I believe.
– Swanny
Feb 11 '14 at 21:36
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二维码的生成细节及原理 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...映射成一个字符索引表。如下所示：（其中的SP是空格，Char是字符，Value是其索引值） 编码的过程是把字符两两分组，然后转成下表的45进制，然后转成11bits的二进制，如果最后有一个落单的，那就转成6bits的二进制。而编码模...