mysql 空间数据库中的各个方法函数

 Point函数
参考地址：http://blog.csdn.net/ahg1001/article/details/6749506 

他写的太多了，我挑了一些有用的出来

Point由X和Y坐标构成，可使用下述函数获得它们：

   X(p) 

• 以双精度数值返回点p的X坐标值。

  mysql> <span class="userinput" style="font-weight: bold;">SELECT X(GeomFromText('Point(56.7 53.34)'));</span>+--------------------------------------+| X(GeomFromText('Point(56.7 53.34)')) |+--------------------------------------+|                                 56.7 |+--------------------------------------+

  <span style="font-family: Arial; background-color: rgb(255, 255, 255);">Y(</span><span class="replaceable" style="font-family: Arial; font-style: italic;">p</span><span style="font-family: Arial; background-color: rgb(255, 255, 255);">) </span>

• 以双精度数值返回点p的Y坐标值。

  mysql> <span class="userinput" style="font-weight: bold;">SELECT Y(GeomFromText('Point(56.7 53.34)'));</span>+--------------------------------------+| Y(GeomFromText('Point(56.7 53.34)')) |+--------------------------------------+|                                53.34 |+--------------------------------------+

  </pre></li></ul></div></div><div class="section" style="color:rgb(51,51,51); font-family:Arial; font-size:14px"><p></p><pre code_snippet_id="1900577" snippet_file_name="blog_20160926_5_3610925" class="programlisting" name="code" style="color: rgb(51, 51, 51); font-size: 14px; white-space: pre-wrap; word-wrap: break-word;"><span style="font-family: Arial; background-color: rgb(255, 255, 255);"> LineString函数</span>

  LineString由Point值组成。你可以提取LineString的特定点，计数它所包含的点数，或获取其长度。

  EndPoint(ls)

  • 返回LineString值1s的最后一个点的Point。

    mysql> <span class="userinput" style="font-weight: bold;">SET @ls = 'LineString(1 1,2 2,3 3)';</span>mysql> <span class="userinput" style="font-weight: bold;">SELECT AsText(EndPoint(GeomFromText(@ls)));</span>+-------------------------------------+| AsText(EndPoint(GeomFromText(@ls))) |+-------------------------------------+| POINT(3 3)                          |+-------------------------------------+

    <span style="font-family: Arial; background-color: rgb(255, 255, 255);">GLength(</span><span class="replaceable" style="font-family: Arial; font-style: italic;">ls</span><span style="font-family: Arial; background-color: rgb(255, 255, 255);">)</span>

  • 以双精度数值返回LineString值1s在相关的空间参考系中的长度。

    mysql> <span class="userinput" style="font-weight: bold;">SET @ls = 'LineString(1 1,2 2,3 3)';</span>mysql> <span class="userinput" style="font-weight: bold;">SELECT GLength(GeomFromText(@ls));</span>+----------------------------+| GLength(GeomFromText(@ls)) |+----------------------------+|            2.8284271247462 |+----------------------------+

    <span style="font-family: Arial; background-color: rgb(255, 255, 255);">NumPoints(</span><span class="replaceable" style="font-family: Arial; font-style: italic;">ls</span><span style="font-family: Arial; background-color: rgb(255, 255, 255);">)</span>

  • 返回LineString值1s中的点数。

    mysql> <span class="userinput" style="font-weight: bold;">SET @ls = 'LineString(1 1,2 2,3 3)';</span>mysql> <span class="userinput" style="font-weight: bold;">SELECT NumPoints(GeomFromText(@ls));</span>+------------------------------+| NumPoints(GeomFromText(@ls)) |+------------------------------+|                            3 |+------------------------------+

    <span style="font-family: Arial; background-color: rgb(255, 255, 255);">PointN(</span><span class="replaceable" style="font-family: Arial; font-style: italic;">ls</span><span style="font-family: Arial; background-color: rgb(255, 255, 255);">,</span><span class="replaceable" style="font-family: Arial; font-style: italic;">n</span><span style="font-family: Arial; background-color: rgb(255, 255, 255);">)</span>

  • 返回LineString值1s中的第n个点。点编号从1开始。

    mysql> <span class="userinput" style="font-weight: bold;">SET @ls = 'LineString(1 1,2 2,3 3)';</span>mysql> <span class="userinput" style="font-weight: bold;">SELECT AsText(PointN(GeomFromText(@ls),2));</span>+-------------------------------------+| AsText(PointN(GeomFromText(@ls),2)) |+-------------------------------------+| POINT(2 2)                          |+-------------------------------------+

    <span style="font-family: Arial; background-color: rgb(255, 255, 255);">StartPoint(</span><span class="replaceable" style="font-family: Arial; font-style: italic;">ls</span><span style="font-family: Arial; background-color: rgb(255, 255, 255);">)</span>

  • 返回LineString值1s的第一个点的Point。

    mysql> <span class="userinput" style="font-weight: bold;">SET @ls = 'LineString(1 1,2 2,3 3)';</span>mysql> <span class="userinput" style="font-weight: bold;">SELECT AsText(StartPoint(GeomFromText(@ls)));</span>+---------------------------------------+| AsText(StartPoint(GeomFromText(@ls))) |+---------------------------------------+| POINT(1 1)                            |+---------------------------------------+

• </pre></li></ul></div></div><div class="section" style="color:rgb(51,51,51); font-family:Arial; font-size:14px"><div class="titlepage"><h4 class="title" style="margin:0px; padding:0px">Polygon函数</h4><h4 class="title" style="margin:0px; padding:0px"><span style="white-space:pre"></span>Area(<span class="replaceable" style="font-style:italic">poly</span>)</h4></div><div class="itemizedlist"><ul type="disc"><li><p>以双精度数值形式返回Polygon值<em>poly</em>的面积，根据在其空间参考系中的测量值。</p><pre code_snippet_id="1900577" snippet_file_name="blog_20160926_16_8617578" class="programlisting" name="code" style="white-space: pre-wrap; word-wrap: break-word;">mysql> <span class="userinput" style="font-weight: bold;">SET @poly = 'Polygon((0 0,0 3,3 0,0 0),(1 1,1 2,2 1,1 1))';</span>mysql> <span class="userinput" style="font-weight: bold;">SELECT Area(GeomFromText(@poly));</span>+---------------------------+| Area(GeomFromText(@poly)) |+---------------------------+|                         4 |+---------------------------+

  <span style="font-family: Arial; background-color: rgb(255, 255, 255);">ExteriorRing(</span><span class="replaceable" style="font-family: Arial; font-style: italic;">poly</span><span style="font-family: Arial; background-color: rgb(255, 255, 255);">)</span>

• 以LineString形式返回Polygon值poly的外环。

  mysql> <span class="userinput" style="font-weight: bold;">SET @poly =</span>    -> <span class="userinput" style="font-weight: bold;">'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))';</span>mysql> <span class="userinput" style="font-weight: bold;">SELECT AsText(ExteriorRing(GeomFromText(@poly)));</span>+-------------------------------------------+| AsText(ExteriorRing(GeomFromText(@poly))) |+-------------------------------------------+| LINESTRING(0 0,0 3,3 3,3 0,0 0)           |+-------------------------------------------+

  <span style="font-family: Arial; background-color: rgb(255, 255, 255);">InteriorRingN(</span><span class="replaceable" style="font-family: Arial; font-style: italic;">poly</span><span style="font-family: Arial; background-color: rgb(255, 255, 255);">,</span><span class="replaceable" style="font-family: Arial; font-style: italic;">n</span><span style="font-family: Arial; background-color: rgb(255, 255, 255);">)</span>

• 以LineString形式返回Polygon值poly的第n个内环。环编号从1开始。

  mysql> <span class="userinput" style="font-weight: bold;">SET @poly =</span>    -> <span class="userinput" style="font-weight: bold;">'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))';</span>mysql> <span class="userinput" style="font-weight: bold;">SELECT AsText(InteriorRingN(GeomFromText(@poly),1));</span>+----------------------------------------------+| AsText(InteriorRingN(GeomFromText(@poly),1)) |+----------------------------------------------+| LINESTRING(1 1,1 2,2 2,2 1,1 1)              |+----------------------------------------------+

  <span style="font-family: Arial; background-color: rgb(255, 255, 255);">NumInteriorRings(</span><span class="replaceable" style="font-family: Arial; font-style: italic;">poly</span><span style="font-family: Arial; background-color: rgb(255, 255, 255);">)</span>

• 返回Polygon值poly的内环的数目。

  mysql> <span class="userinput" style="font-weight: bold;">SET @poly =</span>    -> <span class="userinput" style="font-weight: bold;">'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))';</span>mysql> <span class="userinput" style="font-weight: bold;">SELECT NumInteriorRings(GeomFromText(@poly));</span>+---------------------------------------+| NumInteriorRings(GeomFromText(@poly)) |+---------------------------------------+|                                     1 |+---------------------------------------+

   MultiPolygon函数

  Area(mpoly)

• 以双精度数值形式返回MultiPolygon值mpoly的面积，根据在其空间参考系中的测量结果。

  mysql> <span class="userinput" style="font-weight: bold;">SET @mpoly =</span>    -> <span class="userinput" style="font-weight: bold;">'MultiPolygon(((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1)))';</span>mysql> <span class="userinput" style="font-weight: bold;">SELECT Area(GeomFromText(@mpoly));</span>+----------------------------+| Area(GeomFromText(@mpoly)) |+----------------------------+|                          8 |+----------------------------+

  <span style="font-family: Arial; background-color: rgb(255, 255, 255);">GeometryCollection函数</span>

  <span style="font-family: Arial; background-color: rgb(255, 255, 255);">GeometryN(</span><span class="replaceable" style="font-family: Arial; font-style: italic;">gc</span><span style="font-family: Arial; background-color: rgb(255, 255, 255);">,</span><span class="replaceable" style="font-family: Arial; font-style: italic;">n</span><span style="font-family: Arial; background-color: rgb(255, 255, 255);">)</span>

• 返回GeometryCollection值gc中第n个几何对象。几何对象的编号从1开始。

  mysql> <span class="userinput" style="font-weight: bold;">SET @gc = 'GeometryCollection(Point(1 1),LineString(2 2, 3 3))';</span>mysql> <span class="userinput" style="font-weight: bold;">SELECT AsText(GeometryN(GeomFromText(@gc),1));</span>+----------------------------------------+| AsText(GeometryN(GeomFromText(@gc),1)) |+----------------------------------------+| POINT(1 1)                             |+----------------------------------------+

  <span style="font-family: Arial; background-color: rgb(255, 255, 255);">NumGeometries(</span><span class="replaceable" style="font-family: Arial; font-style: italic;">gc</span><span style="font-family: Arial; background-color: rgb(255, 255, 255);">)</span>

• 返回GeometryCollection值gc中几何对象的数目。

  mysql> <span class="userinput" style="font-weight: bold;">SET @gc = 'GeometryCollection(Point(1 1),LineString(2 2, 3 3))';</span>mysql> <span class="userinput" style="font-weight: bold;">SELECT NumGeometries(GeomFromText(@gc));</span>+----------------------------------+| NumGeometries(GeomFromText(@gc)) |+----------------------------------+|                                2 |+----------------------------------+