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Why use apparently meaningless do-while and if-else statements in macros?
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The do ... while and if ... else are there to make it so that a
semicolon after your macro always means the same thing. Let's say you
had something like your second macro.
#define BAR(X) f(x); g(x)
Now if you were to use BAR(X); in an if ...
Oracle nvarchar和varchar相互转换、联合查询 - 数据库(内核) - 清泛网 - ...
...要对数据类型进行转换。
Specifying the USING CHAR_CS argument converts text into the database character set. The output datatype is VARCHAR2.
Specifying the USING NCHAR_CS argument converts text into the national character set. The output datatype isNVARCHAR2.
（A表字段c_xxx:varch...
nvarchar和varchar相互转换、联合查询 - ORACLE - 清泛IT论坛，有思想、有深度
...要对数据类型进行转换。
Specifying the USING CHAR_CS argument converts text into the database character set. The output datatype is VARCHAR2.
Specifying the USING NCHAR_CS argument converts text into the national character set. The output datatype is NVARCHAR2.
（A表字段c_xxx:varc...
Is there a way to loop through a table variable in TSQL without using a cursor?
... — set based operations will perform faster in every case I can think of and will normally use simpler code.
Depending on your data it may be possible to loop using just SELECT statements as shown below:
Declare @Id int
While (Select Count(*) From ATable Where Processed = 0) > 0
Begin
Se...
Change from SQLite to PostgreSQL in a fresh Rails project
...in SQLite (The dev and production). Since I am moving to heroku, I want to convert my database to PostgreSQL.
13 Answers
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How to create a new object instance from a Type
...l.
There are a lot of overloads for passing parameters to the constructor and such. Check out the documentation at:
http://msdn.microsoft.com/en-us/library/system.activator.createinstance.aspx
or (new path)
https://docs.microsoft.com/en-us/dotnet/api/system.activator.createinstance
Her...
Where is array's length property defined?
... method clone, which overrides the method of the same name in class Object and throws no checked exceptions. The return type of the clone method of an array type T[] is T[].
A clone of a multidimensional array is shallow, which is to say that it creates only a single new array. Subarrays are sh...
What are some uses of template template parameters?
... all specializations of H.
NOTE: I've been programming c++ for many years and have only needed this once. I find that it is a rarely needed feature (of course handy when you need it!).
I've been trying to think of good examples, and to be honest, most of the time this isn't necessary, but let's co...
What does Expression.Quote() do that Expression.Constant() can’t already do?
...e quote operator is an operator which induces closure semantics on its operand. Constants are just values.
Quotes and constants have different meanings and therefore have different representations in an expression tree. Having the same representation for two very different things is extremely confu...
C default arguments
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Not really. The only way would be to write a varargs function and manually fill in default values for arguments which the caller doesn't pass.
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