如何在 t-sql 中声明一个可为空的局部变量？
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How to declare a nullable local variable in t-sql?
提问by ricky
I tried the following statement but failed with compile error.
declare @myValue int NULL
我尝试了以下语句，但因编译错误而失败。
declare @myValue int NULL
回答by P?????
If you are trying to make the variable as NOT NULLvariable which will not accept any NULLvalues then I don't think it is possible.
如果您试图将变量设为NOT NULL不接受任何NULL值的变量，那么我认为这是不可能的。
MSDNsays
MSDN说
After declaration, all variables are initialized as
NULL, unless a value is provided as part of the declaration
声明后，所有变量都初始化为
NULL，除非在声明中提供了一个值
so you don't have to mention it explicitly
所以你不必提及它 explicitly
回答by Ganesh_Devlekar
Your syntax is wrong. By default all variables are nullable
你的语法是错误的。默认情况下，所有变量都可以为空
declare @myValue int=NULL
OUTPUT
输出
select @myValue
NULL
