Question

您正在开发一个应用程序，它将当前位置坐标存储到数据库中，当一个人第二次到达同一位置（在100米内）时，我需要显示一个警报。为此我使用了sqlite的距离在打开sqlite数据库后提供堆栈溢出。然后我正在使用

SELECT * from table ORDER BY distance

我用过这段代码......

if (sqlite3_open([dbPath UTF8String], &dataBase) == SQLITE_OK) {

    sqlite3_create_function(dataBase, "distance", 4, SQLITE_UTF8, NULL, &distanceFunc, NULL, NULL);
   NSString *sqlQuery=[NSString stringWithFormat:@"SELECT * FROM %@ ORDER BY distance(uacl_latitude,uacl_lognitude,%f,%f)",NSLocalizedString(@"TABLE_USER_LOCATION", nil),[self.currentLatitude doubleValue],[self.currentLongitude doubleValue]];

    NSLog(@"%@",sqlQuery);
    sqlite3_stmt *selectstmt = NULL;


    if(sqlite3_prepare_v2(dataBase,[sqlQuery cStringUsingEncoding:NSASCIIStringEncoding],-1,&selectstmt,NULL)==SQLITE_OK) {

        while(sqlite3_step(selectstmt) == SQLITE_ROW) {

            self.latitude =sqlite3_column_double(selectstmt, 4);
            self.longitude = sqlite3_column_double(selectstmt, 5);                NSDictionary *dict=[NSDictionary dictionaryWithObjectsAndKeys:[NSString stringWithFormat:@"%f",self.latitude],@"LATI",[NSString stringWithFormat:@"%f",self.longitude],@"LONGI",nil];
            [array addObject:dict];
        }
    }
} else {
    //Even though the open call failed, close the database connection to release all the memory.

    sqlite3_close(dataBase);
}

这样，距离函数没有调用，如果我替换正在执行ORDERBY distance Query的“SELECT * from Table PrepareV2”，则prepareV2语句也没有执行。
请帮助....

Sqlite_3距离函数

0 个答案: