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Replacing NAs with latest non-NA value
In a data.frame (or data.table), I would like to "fill forward" NAs with the closest previous non-NA value. A simple example, using vectors (instead of a data.frame ) is the following:
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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
...12，14bits，编成多长还要看二维码的尺寸（下面有一个表Table 3说明了这点）
Alphanumeric mode 字符编码。包括 0-9，大写的A到Z（没有小写），以及符号$ % * + – . / : 包括空格。这些字符会映射成一个字符索引表。如下所示：（其...
Sql query to insert datetime in SQL Server
I want to insert a datetime value into a table(SQL Server) using the sql query below
7 Answers
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SQL Server Output Clause into a scalar variable
Is there any "simple" way to do this or I need to pass by a table variable with the "OUTPUT ... INTO" syntax?
3 Answers
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SQL Server - where is “sys.functions”?
...ECT *
FROM sys.objects
WHERE type IN ('FN', 'IF', 'TF') -- scalar, inline table-valued, table-valued
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MySQL “incorrect string value” error when save unicode string in Django
...developer here)
To solve this you need to:
Change your MySQL database, table and columns to use the utf8mb4 character set (only available from MySQL 5.5 onwards)
Specify the charset in your Django settings file as below:
settings.py
DATABASES = {
'default': {
'ENGINE':'django.db....
Why isn't SQL ANSI-92 standard better adopted over ANSI-89?
...e one and the USING Clause is another. IMHO, the addition of a column to a table shouldn't break code but a NATURAL JOIN breaks in a most egregious fashion. The "best" way to break is by compilation error. For example if you SELECT * somewhere, the addition of a column could fail to compile. The nex...
Is C++14 adding new keywords to C++?
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Table 4 (Keywords) in N3936 (C++14):
alignas continue friend register true
alignof decltype goto reinterpret_cast try
asm default ...
How to add JTable in JPanel with null layout?
I want to add JTable into JPanel whose layout is null . JPanel contains other components. I have to add JTable at proper position.
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How to create a unique index on a NULL column?
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create unique index UIX on MyTable (Column1) where Column1 is not null
– Jørn Schou-Rode
Dec 2 '10 at 14:54
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