从查询中省略空白/空记录？ （ColdFusion的）

Question

我目前正试图找到一种方法来省略字段为空的搜索结果。简单的方法是使用<cfif len(example) neq 0>#example#</cfif>，但这意味着我的查询不必要地提取结果。

<cfquery datasource="#datasource#" name="search">
    <cfif URL.for eq "names">
        Select artist_id, artist_name
        From artists
        Where approved = 1
        And active = 1
        <cfif StructKeyExists("URL.search")>
            <cfif URL.find eq "contains">
                And name LIKE <cfqueryparam cfsqltype="cf_sql_varchar" value="%#URL.search#%">
            <cfelseif URL.find eq "matches">
                And name = <cfqueryparam cfsqltype="cf_sql_varchar" value="#URL.search#">
            </cfif>
        </cfif>
        Order By name Asc

    <cfelseif URL.for eq "locations">
        <cfif URL.sort eq "town-az" or URL.sort eq "town-za">
            Select Distinct town
        <cfelseif URL.sort eq "county-az" or URL.sort eq "county-za">
            Select Distinct county
        <cfelseif URL.sort eq "country-az" or URL.sort eq "country-za">
            Select Distinct country
        </cfif>
        From artists
        Where approved = 1
        And active = 1
        <cfif StructKeyExists("URL.search")>
            <cfif URL.find eq "contains">
                <cfif URL.sort eq "town-az">
                    And town LIKE <cfqueryparam cfsqltype="cf_sql_varchar" value="%#URL.search#%">
                    Order By town Asc
                <cfelseif URL.sort eq "town-za">
                    And town LIKE <cfqueryparam cfsqltype="cf_sql_varchar" value="%#URL.search#%">
                    Order By town Desc
                <cfelseif URL.sort eq "county-az">
                    And county IS NOT NULL
                    And county LIKE <cfqueryparam cfsqltype="cf_sql_varchar" value="%#URL.search#%">
                    Order By county Asc
                <cfelseif URL.sort eq "county-za">
                    And county IS NOT NULL
                    And county LIKE <cfqueryparam cfsqltype="cf_sql_varchar" value="%#URL.search#%">
                    Order By county Desc
                <cfelseif URL.sort eq "country-az">
                    And country LIKE <cfqueryparam cfsqltype="cf_sql_varchar" value="%#URL.search#%">
                    Order By country Asc
                <cfelseif URL.sort eq "country-za">
                    And country LIKE <cfqueryparam cfsqltype="cf_sql_varchar" value="%#URL.search#%">
                    Order By country Desc
                </cfif>

            <cfelseif URL.find eq "matches">
                <cfif URL.sort eq "town-az">
                    And town = <cfqueryparam cfsqltype="cf_sql_varchar" value="#URL.search#">
                    Order By town Asc
                <cfelseif URL.sort eq "town-za">
                    And town = <cfqueryparam cfsqltype="cf_sql_varchar" value="#URL.search#">
                    Order By town Desc
                <cfelseif URL.sort eq "county-az">
                    And county IS NOT NULL
                    And county = <cfqueryparam cfsqltype="cf_sql_varchar" value="#URL.search#">
                    Order By county Asc
                <cfelseif URL.sort eq "county-za">
                    And county IS NOT NULL
                    And county = <cfqueryparam cfsqltype="cf_sql_varchar" value="#URL.search#">
                    Order By county Desc
                <cfelseif URL.sort eq "country-az">
                    And country = <cfqueryparam cfsqltype="cf_sql_varchar" value="#URL.search#">
                    Order By country Asc
                <cfelseif URL.sort eq "country-za">
                    And country = <cfqueryparam cfsqltype="cf_sql_varchar" value="#URL.search#">
                    Order By country Desc
                </cfif>
            </cfif>
        </cfif>
    </cfif>
</cfquery>

注册时town和country字段是必填字段，因此这些字段没有问题，但我没有将县/州字段设为必填字段，因此如果值为NULL，则值为NULL用户不进入县或州。如上所述，我可以简单地使用len()方法仅显示具有字符的结果，但这意味着我的查询将拉出NULL结果，而不需要将其拉出。我已经包含了AND county IS NOT NULL，但这似乎没有任何区别。有人能够指出我正确的方向吗？感谢。

Answer 1

最终这是一个微不足道的错误，但是如果你根据现有的变量添加额外的语句，那么值得向任何找到类似问题的人指出，检查它们在查询的所有级别都不是必需的。< / p>

SELECT DISTINCT county
FROM   artists
WHERE  active = 1
AND    approved = 1
<cfif URL.sort eq "county-az" or URL.sort eq "county-za">
    AND county IS NOT NULL
</cfif>

以上是我需要在查询核心内更改的内容，请注意我已将该部分包括在内以排除所有NULL结果 BEFORE 检查是否存在搜索字词。

Answer 2

尝试在sql server中使用@variables的动态方法：

declare @county varchar(50), @countylike varchar(50)

添加一些逻辑来设置ColdFusion中存在的变量：

<cfif ....>

</cfif>

然后在where子句中添加这样的东西：

and (@county is null or county = @county)
and (@countylike is null or county like '%'+ @countylike +'%')