查找附近的地点使用SQLite和Android [英] Find near locations with SQLite and Android

问题描述

我在约经度，纬度和描述信息SQL​​ite数据库的数据表。考虑到一定的位置，我想获得的所有与该位置近距离（10块）的行。

I have a data table in my SQLite database with information about longitude, latitude and description. Given a certain location, I would like to get all the rows with a near distance (10 blocks) from that location.

这是数据是如何加载：

values.put(LONGITUD_COLUMN,  (int) (-64.14802 * 1E6));
values.put(LATITUD_COLUMN, (int) (-31.36498 * 1E6));

到目前为止，这是我在code：

So far this is what I have in code:

private int cuadras = (int)(-0.02 * 1E6) ; //10 blocks aprox, I guess
private int current_latitude = 0;
private int current_longitude = 0;

current_latitude和current_longitude，都含有（从LocationListener的）：

current_latitude and current_longitude, are loaded with (from LocationListener):

public void onLocationChanged(Location location) {
 current_latitude = (int) (location.getLatitude() * 1E6);
 current_longitude = (int) (location.getLongitude() * 1E6);
}

和SQLite的查询是如下：

And the SQLite query is as follows:

String sql = "LATITUD_COLUMN > (" + (current_latitude + cuadras) + ") AND "
+ "LATITUD_COLUMN < (" + (current_latitude - cuadras) +") AND "
+ "LONGITUD_COLUMN > ("+ (current_longitude - cuadras) +") AND "
+ "LONGITUD_COLUMN < ("+ (current_longitude + cuadras) +")";

通过这样的结果：

LATITUD_COLUMN > (-31398170) AND LATITUD_COLUMN < (-31358170) AND LONGITUD_COLUMN > (-64132838) AND LONGITUD_COLUMN < (-64172838)

该查询返回任何结果，我的问题是，我怎么能查询数据库把所有的位置靠近我当前的位置？

That query returns no results at all, my question is, how can I query the DataBase bringing all the locations near my current location?

谢谢！

推荐答案

您似乎有你的+和 - 混合起来：

You appear to have your + and - mixed up:

String sql = "LATITUD_COLUMN > (" + (current_latitude + cuadras) + ") AND "
+ "LATITUD_COLUMN < (" + (current_latitude - cuadras) +") AND "
+ "LONGITUD_COLUMN > ("+ (current_longitude - cuadras) +") AND "
+ "LONGITUD_COLUMN < ("+ (current_longitude + cuadras) +")";

应

String sql = "LATITUD_COLUMN > (" + (current_latitude + cuadras) + ") AND "
+ "LATITUD_COLUMN < (" + (current_latitude - cuadras) +") AND "
+ "LONGITUD_COLUMN > ("+ (current_longitude + cuadras) +") AND "
+ "LONGITUD_COLUMN < ("+ (current_longitude - cuadras) +")";

请注意调换的+和 - 在最后两行

Note the swapped + and - in the last two lines.

LONGITUD_COLUMN＆GT; （-64132838）和LONGITUD_COLUMN＆LT; （-64172838）始终为false。 ： - ）

LONGITUD_COLUMN > (-64132838) AND LONGITUD_COLUMN < (-64172838) is always false. :-)

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