Question

我想返回此域中的项目数。我知道count（*）返回一个名为Domain的项，其中包含一个名为Count的属性。我怎样才能获得伯爵的价值？

@try {
    SimpleDBSelectRequest  *selectRequest2  = [[SimpleDBSelectRequest alloc] initWithSelectExpression:@"select count(*) from %@"];
    SimpleDBSelectResponse *selectResponse = [[AmazonClientManager sdb] select:selectRequest2];

    for (SimpleDBItem *item in selectResponse.items) {
    if ( [item.name isEqualToString:@"Domain"])
    {
        NSLog(@"Attributes = %@",[item.attributes objectAtIndex:0]);
    }
    }
}
@catch (AmazonServiceException *exception) {
    NSLog(@"Exception = %@", exception);
}

我为属性获得了这个：

Attributes = {Name: Count,AlternateNameEncoding: (null),Value: 3,AlternateValueEncoding: (null),<SimpleDBAttribute: 0x8667120>}

如何从中获取价值3？

Answer 1

selectResponse应该有items属性，这是SimpleDBReplaceableAttribute个实例的可变数组。应该有一个name属性为“Count”且其value属性是计数的字符串表示形式。

这将是：

    SimpleDBReplaceableAttribute *attribute = [[selectResponse items] objectAtIndex:0];
    NSInteger count = [[attribute value] integerValue];

Answer 2

这有效：

for (SimpleDBAttribute *attr in item.attributes) { if ([attr.name isEqualToString:@"Count"]) { int total = [attr.value intValue];

从SimpleDB iPhone中选择count（*）

2 个答案: