Question

好的，我有这个字段：code varchar(255)。它包含我们的导出例程中使用的一些值，如

DB84
DB34
3567
3568

我只需要选择自动生成的（完全数字）字段

WHERE is_numeric(table.code)

is_numeric()检查code字段是否仅包含正数。

你能提出任何可以在mysql 5.1和oracle 10g下工作的东西吗？

Answer 1

下面是SQL Server，MySQL和Oracle的三个独立实现。没有使用（或可以）相同的方法，因此似乎没有跨DBMS方式来做到这一点。对于MySQL和Oracle，只显示简单的整数测试;对于SQL Server，将显示完整的数字测试。

对于SQL Server： 请注意，isnumeric（'。'）返回1 ..但实际上它不能转换为float。像'1e6'这样的文本不能直接转换为数字，但你可以通过float，然后是数字。

;with tmp(x) as (
    select 'db01' union all select '1' union all select '1e2' union all
    select '1234' union all select '' union all select null union all
    select '1.2e4' union all select '1.e10' union all select '0' union all
    select '1.2e+4' union all select '1.e-10' union all select '1e--5' union all
    select '.' union all select '.123' union all select '1.1.23' union all
    select '-.123' union all select '-1.123' union all select '--1' union all
    select '---1.1' union all select '+1.123' union all select '++3' union all
    select '-+1.123' union all select '1 1' union all select '1e1.3' union all
    select '1.234' union all select 'e4' union all select '+.123' union all
    select '1-' union all select '-3e-4' union all select '+3e-4'  union all
    select '+3e+4' union all select '-3.2e+4' union all select '1e1e1' union all
    select '-1e-1-1')

select x, isnumeric(x),
    case when x not like '%[^0-9]%' and x >'' then convert(int, x) end as SimpleInt,
    case
    when x is null or x = '' then null -- blanks
    when x like '%[^0-9e.+-]%' then null -- non valid char found
    when x like 'e%' or x like '%e%[e.]%' then null -- e cannot be first, and cannot be followed by e/.
    when x like '%e%_%[+-]%' then null -- nothing must come between e and +/-
    when x='.' or x like '%.%.%' then null -- no more than one decimal, and not the decimal alone
    when x like '%[^e][+-]%' then null -- no more than one of either +/-, and it must be at the start
    when x like '%[+-]%[+-]%' and not x like '%[+-]%e[+-]%' then null
    else convert(float,x)
    end
from tmp order by 2, 3

对于MySQL

create table tmp(x varchar(100));
insert into tmp
    select 'db01' union all select '1' union all select '1e2' union all
    select '1234' union all select '' union all select null union all
    select '1.2e4' union all select '1.e10' union all select '0' union all
    select '1.2e+4' union all select '1.e-10' union all select '1e--5' union all
    select '.' union all select '.123' union all select '1.1.23' union all
    select '-.123' union all select '-1.123' union all select '--1' union all
    select '---1.1' union all select '+1.123' union all select '++3' union all
    select '-+1.123' union all select '1 1' union all select '1e1.3' union all
    select '1.234' union all select 'e4' union all select '+.123' union all
    select '1-' union all select '-3e-4' union all select '+3e-4'  union all
    select '+3e+4' union all select '-3.2e+4' union all select '1e1e1' union all
    select '-1e-1-1';

select x,
    case when x not regexp('[^0-9]') then x*1 end as SimpleInt
from tmp order by 2

对于Oracle

case when REGEXP_LIKE(col, '[^0-9]') then col*1 end

cross-dbms检查字符串是否为数字的方法

1 个答案: