我需要为SimpleDB构造一个selectExpression,其中我只需要属性为to到X的项目,按属性Y的降序排序。到目前为止我所有的都是:
NSString *selectExpression = [NSString stringWithFormat:@"select itemName() from `%@`",domainString];
@try {
SimpleDBSelectRequest *selectRequest2 = [[[SimpleDBSelectRequest alloc] initWithSelectExpression:selectExpression] autorelease];
SimpleDBSelectResponse *selectResponse = [[Constants sdb] select:selectRequest2];
if (items == nil) {
items = [[NSMutableArray alloc] initWithCapacity:[selectResponse.items count]];
}
else {
[items removeAllObjects];
}
for (SimpleDBItem *item in selectResponse.items) {
[items addObject:item.name];
}
[items sortUsingSelector:@selector(compare:)];
}
@catch (AmazonServiceException *exception) {
NSLog(@"Exception = %@", exception);
}
我宁愿只选择属性为X的项目(上面),而不是获取所有项目然后排序。我该如何添加?它是否包含在selectExpression字符串中或其他位置。非常感谢!
答案 0 :(得分:0)
NSString *selectExpression = [NSString stringWithFormat:@"select itemName() from `%@` where X = '%@' order by 'X' descending",domainName,attributeValue];
答案 1 :(得分:0)
试试这个 -
Select x,y from <domain_name> where itemName() is not null order by itemName() asc