64

有没有一种简单的方法可以确定 varchar 是否为数字？

例子：

abc123 --> 没有数字

123 --> 是的，它是一个数字

谢谢 ：）

4

11 回答 11

143

ISNUMERIC 不会 - 它告诉您字符串可以转换为任何数字类型，这几乎总是无意义的信息。例如，根据 ISNUMERIC，以下所有内容都是数字：

£, $, 0d0

如果您想检查数字并且只检查数字，那么您想要一个否定的 LIKE 表达式：

not Value like '%[^0-9]%'
于 2011-01-05T11:10:27.363 回答
35

ISNUMERIC会做

检查文章中的注释部分。

于 2011-01-05T11:03:40.383 回答
29

你可以这样检查

declare @vchar varchar(50)
set @vchar ='34343';
select case when @vchar not like '%[^0-9]%' then 'Number' else 'Not a Number' end
于 2011-01-05T11:09:49.513 回答
21

使用 SQL Server 2012+，如果您有特定需求，可以使用 TRY_* 函数。例如，

-- will fail for decimal values, but allow negative values
TRY_CAST(@value AS INT) IS NOT NULL 

-- will fail for non-positive integers; can be used with other examples below as well, or reversed if only negative desired
TRY_CAST(@value AS INT) > 0

-- will fail if a $ is used, but allow decimals to the specified precision
TRY_CAST(@value AS DECIMAL(10,2)) IS NOT NULL 

-- will allow valid currency
TRY_CAST(@value AS MONEY) IS NOT NULL  

-- will allow scientific notation to be used like 1.7E+3
TRY_CAST(@value AS FLOAT) IS NOT NULL
于 2016-03-18T14:55:46.410 回答
9

我遇到了允许十进制值的需要，所以我使用了not Value like '%[^0-9.]%'

于 2014-12-01T18:20:05.100 回答
3

Wade73 对小数的回答不太适用。我已经修改它只允许一个小数点。

declare @MyTable table(MyVar nvarchar(10));
insert into @MyTable (MyVar) 
values 
    (N'1234')
    , (N'000005')
    , (N'1,000')
    , (N'293.8457')
    , (N'x')
    , (N'+')
    , (N'293.8457.')
    , (N'......');

-- This shows that Wade73's answer allows some non-numeric values to slip through.
select * from (
    select 
        MyVar
        , case when MyVar not like N'%[^0-9.]%' then 1 else 0 end as IsNumber 
    from 
        @MyTable
) t order by IsNumber;

-- Notice the addition of "and MyVar not like N'%.%.%'".
select * from (
    select 
        MyVar
        , case when MyVar not like N'%[^0-9.]%' and MyVar not like N'%.%.%' then 1 else 0 end as IsNumber 
    from 
        @MyTable
) t 
order by IsNumber;
于 2015-11-13T21:19:13.090 回答
2

Damien_The_Unbeliever 指出他只对数字有好处

Wade73 加了一点处理小数点

neizan 做了一个额外的调整

不幸的是，似乎没有一个可以处理负值，并且它们似乎在值中存在逗号问题......

这是我的调整以获取负值和带有逗号的值

declare @MyTable table(MyVar nvarchar(10));
insert into @MyTable (MyVar) 
values 
(N'1234')
, (N'000005')
, (N'1,000')
, (N'293.8457')
, (N'x')
, (N'+')
, (N'293.8457.')
, (N'......')
, (N'.')
, (N'-375.4')
, (N'-00003')
, (N'-2,000')
, (N'3-3')
, (N'3000-')
;

-- This shows that Neizan's answer allows "." to slip through.
select * from (
select 
    MyVar
    , case when MyVar not like N'%[^0-9.]%' then 1 else 0 end as IsNumber 
from 
    @MyTable
) t order by IsNumber;

-- Notice the addition of "and MyVar not like '.'".
select * from (
select 
    MyVar
    , case when MyVar not like N'%[^0-9.]%' and MyVar not like N'%.%.%' and MyVar not like '.' then 1 else 0 end as IsNumber 
from 
    @MyTable
) t 
order by IsNumber;

--Trying to tweak for negative values and the comma
--Modified when comparison
select * from (
select 
    MyVar
    , case 
        when MyVar not like N'%[^0-9.,-]%' and MyVar not like '.' and isnumeric(MyVar) = 1 then 1
        else 0 
    end as IsNumber 
from 
    @MyTable
) t 
order by IsNumber;
于 2017-02-09T17:27:20.210 回答
1 
DECLARE @A nvarchar(100) = '12'
IF(ISNUMERIC(@A) = 1)
BEGIN
    PRINT 'YES NUMERIC'
END
于 2015-11-03T05:52:27.747 回答
1

Neizan 的代码让值只有一个“。” 通过。冒着过于迂腐的风险，我又添加了一个AND子句。

declare @MyTable table(MyVar nvarchar(10));
insert into @MyTable (MyVar) 
values 
    (N'1234')
    , (N'000005')
    , (N'1,000')
    , (N'293.8457')
    , (N'x')
    , (N'+')
    , (N'293.8457.')
    , (N'......')
    , (N'.')
    ;

-- This shows that Neizan's answer allows "." to slip through.
select * from (
    select 
        MyVar
        , case when MyVar not like N'%[^0-9.]%' then 1 else 0 end as IsNumber 
    from 
        @MyTable
) t order by IsNumber;

-- Notice the addition of "and MyVar not like '.'".
select * from (
    select 
        MyVar
        , case when MyVar not like N'%[^0-9.]%' and MyVar not like N'%.%.%' and MyVar not like '.' then 1 else 0 end as IsNumber 
    from 
        @MyTable
) t 
order by IsNumber;
于 2016-02-17T17:21:14.313 回答
0

不要忘记从您的数据中排除回车！！！

如：

SELECT 
  Myotherval
  , CASE WHEN TRIM(REPLACE([MyVal], char(13) + char(10), '')) not like '%[^0-9]%' and RTRIM(REPLACE([MyVal], char(13) + char(10), '')) not like '.' and isnumeric(REPLACE([MyVal], char(13) + char(10), '')) = 1 THEN 'my number: ' +  [MyVal]
             ELSE ISNULL(Cast([MyVal] AS VARCHAR(8000)), '')
        END AS 'MyVal'
FROM MyTable
于 2019-11-18T15:21:20.253 回答
0

如果要对具有固定长度的字段正整数添加约束

ALTER TABLE dbo.BankBranchType  
ADD CONSTRAINT CK_TransitNumberMustBe5Digits 
CHECK (TransitNumber NOT like '%[^0-9]%'  
       AND LEN(TransitNumber) = 5)
于 2021-08-16T15:32:17.163 回答