PostgreSQL 8.0.0 ��ĵ��PostgreSQL �й� ��
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8.7. ��

��ͱ�ʾ��ά��ƽ��塣 Table 8-16 ��ʾ��PostgreSQL ��õļ��͡� ��ͣ��㣬��͵Ļ��

Table 8-16. ��

��	�洢�ռ�	��	��ʽ
`point`	16 �ֽ�	�ռ��һ��	(x,y)
`line`	32 �ֽ�	(��)ֱ�ߣ�δ��ȫʵ�֣�	((x1,y1),(x2,y2))
`lseg`	32 �ֽ�	��ޣ��߶�	((x1,y1),(x2,y2))
`box`	32 �ֽ�	��	((x1,y1),(x2,y2))
`path`	16+16n �ֽ�	�պ�·��(��)	((x1,y1),...)
`path`	16+16n �ֽ�	��·��	[(x1,y1),...]
`polygon`	40+16n �ֽ�	��(��պ�·��)	((x1,y1),...)
`circle`	24 �ֽ�	Բ(Բ�ĺͰ뾶)	<(x,y),r>

��һϵ�зḻ�ĺ��Ͳ��и��ּ��μ��㣬 ��죬ת��ת�ͼ��ཻ�ȡ� �� Section 9.10 ��н��͡�

8.7.1. Point��㣩

��Ǽ��͵Ļ��ά��쵥λ�� ﷨�� point ��ֵ��

( x , y )
  x , y

��Ĳ�� ø��ʾ�ĵ�� x �� y ��ꡣ

8.7.2. �߶�

�߶� ��lseg��һ�Ե��ġ� lseg ��ֵ��﷨��

( ( x1 , y1 ) , ( x2 , y2 ) )
  ( x1 , y1 ) , ( x2 , y2 )  
    x1 , y1   ,   x2 , y2

�� (x1,y1)�� (x2,y2) ��߶εĶ˵㡣

8.7.3. Box��

��һ�ԶԽǵ��ʾ�ġ� box ��ֵ��﷨��

( ( x1 , y1 ) , ( x2 , y2 ) )
  ( x1 , y1 ) , ( x2 , y2 )  
    x1 , y1   ,   x2 , y2

�� (x1,y1) �� (x2,y2) �Ƿ��ε�һ�ԶԽǵ㡣

��ʹ�õ�һ��﷨��ʱ��ϽǺ��½ǵ�˳��С� ��Ҳ��һ�ԶԽǵ㡣 ��ʱ��ȴ��кʹ洢�Ľ��м��½Ǻ��Ͻ�Ȼ��ٴ洢��

8.7.4. Path��·��

·��һϵ��ӵĵ��ɡ�·�����ģ� Ҳ��Ϊ�б��е�һ��һ��û��ӣ� Ҳ���պ��ģ��ʱ��Ϊ��һ��һ��

path ��ֵ��﷨��

( ( x1 , y1 ) , ... , ( xn , yn ) )
[ ( x1 , y1 ) , ... , ( xn , yn ) ]
  ( x1 , y1 ) , ... , ( xn , yn )  
  ( x1 , y1   , ... ,   xn , yn )  
    x1 , y1   , ... ,   xn , yn

��ĵ��·��߶εĶ˵㡣 ��[]��һ��ŵ�·��Բ��()��һ��պϵ�·��

·��ʹ�õ�һ��﷨��

8.7.5. Polygon��Σ�

��һϵ�е��εĶ��㣩��ο��Ϊ��պ�·��һ�� Ǵ洢��ʽ��һ��Լ��һ��֧�ֹ��/��

polygon ��ֵ��﷨��

( ( x1 , y1 ) , ... , ( xn , yn ) )
  ( x1 , y1 ) , ... , ( xn , yn )  
  ( x1 , y1   , ... ,   xn , yn )  
    x1 , y1   , ... ,   xn , yn

��ĵ��ɶ��α߽��߶εĶ˵㡣

��ʹ�õ�һ��﷨��

8.7.6. Circle��Բ��

Բ��һ��Բ�ĺ�һ��뾶�� circle ��ֵ��﷨��ʾ��

< ( x , y ) , r >
( ( x , y ) , r )
  ( x , y ) , r  
    x , y   , r

�� (x,y) ��Բ�ģ��rԲ�İ뾶

Բ��õ�һ�ָ�ʽ��

8.7. ��������

8.7.1. Point���㣩