SQL 字符串变量的空或空检查
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Null or empty check for a string variable
提问by Bharath
if((isnull(@value,''))='')
I want to know whether the above piece of code works in checking if the variable is null or empty.
我想知道上面的代码在检查变量是空还是空时是否有效。
回答by Guffa
Yes, that code does exactly that.
是的，该代码正是这样做的。
You can also use:
您还可以使用：
if (@value is null or @value = '')
Edit:
编辑：
With the added information that @valueis an intvalue, you need instead:
使用@value作为int值的附加信息，您需要：
if (@value is null)
An intvalue can never contain the value ''.
一个int值不能包含值''。
回答by AnasChavadi
Use This way is Better
使用这种方式更好
if LEN(ISNULL(@Value,''))=0
This check the field is emptyor NULL
此检查字段是empty或NULL
回答by Tim Schmelter
回答by bvr
Yes, it works. Check the below example. Assuming @value is not int
是的，它有效。检查下面的例子。假设@value 不是int
WITH CTE
AS
(
SELECT NULL AS test
UNION
SELECT '' AS test
UNION
SELECT '123' AS test
)
SELECT
CASE WHEN isnull(test,'')='' THEN 'empty' ELSE test END AS IS_EMPTY
FROM CTE
Result :
结果 ：
IS_EMPTY
--------
empty
empty
123
回答by milan
Try this:
尝试这个：
ISNULL(IIF (ColunmValue!='',ColunmValue, 'no units exists') , 'no units exists') AS 'ColunmValueName'
回答by Fahad Akbar
You can try
你可以试试
<column_name> is null
in the whereclause.
在where条款中。
回答by Ajay Jamwal
You can try this.....
你可以试试这个......
DECLARE @value Varchar(100)=NULL
IF(@value = '' OR @value IS NULL)
BEGIN
select 1
END
ELSE
BEGIN
select 0
END
回答by Sérgio Roberto Penha Heredia
declare @sexo as char(1)
select @sexo='F'
select * from pessoa
where isnull(Sexo,0) =isnull(@Sexo,0)
