MySQL查询结果有些奇怪 [英] mysql query result in something weird

问题描述

大家好...我只是想问为什么我的查询听起来很奇怪?您设置了我刚刚创建的查询，该查询将根据ID号搜索结果，但是当我的查询生成结果时，我感到惊讶，因为它返回了结果...这是我的查询

Hi guys... i just want to ask why is it that my query is acting weird? you set i just created a query that will search a result based on the id number but when my query generated a result i was surprised because it returned a result... heres my query

SELECT id,name,status from tbl_priviledge where  id >= ''sdfasdfasdf'' LIMIT 0, 2

我原本希望返回空结果，但它返回了一个结果...我知道没有ID的值为

i was expecting to return an empty result but it returned a result... which i know there is no id with a value of

''sdfasdfasdf''

，所以我该如何解决呢?

so how do i fix this?

推荐答案

在查询中使用输入之前，应先对其进行验证.

MySQL有一些比较不同类型的规则，这解释了为什么"sdfasdfasdf"的求值为0:
http://dev.mysql.com/doc/refman/5.5/en/type- conversion.html [^ ]

You should validate your inputs before you use them in queries.

MySQL has some rules for how it compares different types, which explains why ''sdfasdfasdf'' evaluates as 0:
http://dev.mysql.com/doc/refman/5.5/en/type-conversion.html[^]

不要使用> ="-请使用"="代替:

Don''t use ">=" - use "=" instead:

SELECT id,name,status from tbl_priviledge where  id >= 'sdfasdfasdf' LIMIT 0, 2

成为

SELECT id,name,status from tbl_priviledge where  id = 'sdfasdfasdf' LIMIT 0, 2

SQL可以比较字符串和数字...

SQL can compare strings asa well as numbers...

如果您要测试不平等性(即您不想搜索id =" sdfasdfasdf")，请使用<>而不是> =.我认为SQL使用单个字母的ascii值比较字符串值.因此，任何以大于"s"的字符(即t，u，v，...，z)开头的字符都被视为大于以"s"开头的字符串

或者您可以使用:

If you want to test for inequility, (i.e. you don''t want to search for id = ''sdfasdfasdf'') use <> instead of >=. I think the SQL compares the string values using the ascii values of the individual letters. So anything starting with a character bigger than ''s'' (i.e. t,u,v,...,z) is considered larger than the strings that start with ''s''

Or you can use:

SELECT id,name,status from tbl_priviledge where NOT (id = 'sdfasdfasdf') LIMIT 0, 2

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