Geography Reference
In-Depth Information
Summary
Databases should consider both geographic representation and cartographic
representation. Based on the nature of the intended geographic information
uses, the creation of a database could consider only geographic representation.
GIS databases are in almost all cases relational databases, which have
great flexibility for geographic information and cartographic needs. You can
think of a database as a set of tables that can be put into relationship with
each other based on characteristics, or what are usually called “attributes.”
They are stored as one of several data types: integer, floating-point, charac-
ter, data and time, or simple large binary objects. These tables are different
from spreadsheets because each value of a characteristic is kept grouped into
a record of all recorded characteristics for that database entity or object.
Tables in relational databases are related using the entity-relationship model.
These database tables are also used for recording attributes that are used for
the symbolization of things and events. Data modeling plays a key part in
preparing the geographic representation and cartographic representation of
geographic information or maps.
In-Depth
ASCII Characters
The partial list of ASCII (American Standard Code for Information Inter-
change) characters below contains the characters and their decimal representa-
tions, which is how the computer stores them. These numbers are further
encoded by the computer in the hexadecimal, and then the binary format.
First, you may note that ASCII characters also include nonprintable characters
(some are not shown in this extract of the character set). You should also note
that letters from other alphabets (e.g., ü or
) are missing. ASCII is being
replaced by the character set UNICODE, which includes those letters, as well
as characters and symbols from many, many other languages. It will be some
time, though, before this newer character set is fully phased in.
Dec. Val. Char.
32 space
33 !
34 “
35 #
36 $
37 %
38 &
39 '
40 (
41 )
42 *
43 +
44 ,
45 -
46 .
47 /
48 0
49 1
50 2
51 3
52 4
53 5
54 6
55 7
56 8
57 9
58 :
59 ;
60
61 =
62
63 ?
64 @
65 A
66 B
67 C
68 D
69 E
70 F
71 G
72 H
73 I
74 J
75 K
76 L
77 M
78 N
79 O
80 P
81 Q
82 R
83 S
84 T
85 U
86 V
87 w
88 X
89 Y
90 Z
91 [
92 \
93 ]
94 ^
95 _
96 '
97 a
98 b
99 c
100 d
101 e
102 f
103 g
104 h
105 i
106 j
107 k
108 l
109 m
110 n
111 o
112 p
113 q
114 r
115 s
116 t
117 u
118 v
119 w
120 x
121 y
122 z
123 {
124 |
125 }
126 ~
127 DEL
Note: More complete ASCII tables are available on the Internet.
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