Question

如果我的问题看起来很奇怪，我很抱歉，希望当我解释它时，这将是可以理解的......

我有这个选择陈述

select 
    cax.CustomerID,
    cax.AddressID,
    c.YearBuilt,
    a.Line1,
    a.Line2,
    a.City,
    a.ZipCode,
    a.StateID,
    a.SubDivision,
    s.Directions
from [CustomerAddressXREF] cax
inner join [Customer] c on c.CustomerID = cax.CustomerID
inner join [Address] a on a.AddressID = cax.AddressID
inner join [SubDivision] s on s.SubDivisionName = a.SubDivision
where cax.CustomerID = 11

并返回以下数据

我知道问题出现在SubDivision列中。如果我注释掉了.SubDivision和s.Directions，那么我会返回1行，这应该基于该语句。我想做的是如果a.SubDivision = N / A，那么我不想将它包含在查询或s.Directions中。

我不知道从哪里开始或从哪里开始关闭它。是否有可能做我想做的事

修改

我正在寻找的结果就是这个

因此，如果SubDivision列包含N / A，则它不会选择SubDivision或Directions

Answer 1

目前尚不清楚你想要归还的结果，所以我们只是在猜测。

根据规范，省略c3p0和mchange-commons-java的值，并用NULL值替换它们......

改变这个：

private static Retrofit retrofit = null;
private static final String CACHE_CONTROL = "Cache-Control";

public static Retrofit getClient(Context context)
{
    if (retrofit==null) {
        retrofit = new Retrofit.Builder()
                .baseUrl(URLS.BASE_URL)
                .addConverterFactory(GsonConverterFactory.create())
                .client(provideOkHttpClient(context))
                .build();
    }
    return retrofit;
}

/**
 * Add Client for adding Authentication headers.
 * @return Retrofit
 */
public static Retrofit getAthenticationClient()
{
    if (retrofit==null) {
        retrofit = new Retrofit.Builder()
                .baseUrl(URLS.BASE_URL)
                .client(ApiIntercepters.AddAuthenticationHeader())
                .addConverterFactory(GsonConverterFactory.create())
                .build();
    }
    return retrofit;
}

public static OkHttpClient provideOkHttpClient(Context context)
{
    return new OkHttpClient.Builder()
            .addNetworkInterceptor(provideCacheInterceptor())
            .cache( provideCache(context))
            .build();
}

private static Cache provideCache (Context context)
{
    Cache cache = null;
    try
    {
        //setup cache
        File httpCacheDirectory = new File(context.getCacheDir(), "responses");
        int cacheSize = 10 * 1024 * 1024; // 10 MiB
        cache = new Cache(httpCacheDirectory, cacheSize);

    }
    catch (Exception e)
    {
        Log.e( "Injector :-> ", "Could not create Cache!" );
    }
    return cache;
}

public static Interceptor provideCacheInterceptor ()
{
    return new Interceptor()
    {
        @Override
        public Response intercept (Chain chain) throws IOException
        {
            Response originalResponse = chain.proceed(chain.request());
            if (RetrofitDemoApp.hasNetwork()) {
                int maxAge = 60; // read from cache for 1 minute
                return originalResponse.newBuilder()
                        .header("Cache-Control", "public, max-age=" + maxAge)
                        .build();
            } else {
                int maxStale = 60 * 60 * 24 * 28; // tolerate 4-weeks stale
                return originalResponse.newBuilder()
                        .header("Cache-Control", "public, only-if-cached, max-stale=" + maxStale)
                        .build();
            }
        }
    };
}

对此：

a.SubDivision

或对此（略有不同但等效）：

a.Directions

如何在select语句期间根据条件从列中选择数据？

1 个答案: