Database Flashcards
What is a database?
Organized data, typically in tables
DBMS
Data base management system (paper, digital)
What is a record?
All of the information about an entity (species, class, volume, height)
What is a field?
A category of information arranged in a column (ID number, Name, Phone number, $ owed).
What is the primary key?
A unique ID (student number)
What is a table?
A set of info for each “subject” (contact info, academic record, accounts.)
What are some advantages of a database?
- Data stored independently of software
- Simple structure
- Redundancy minimized (consistent data)
- Reduced data errors (error checks)
- Easy to update (maintain data)
- ready access to data (Variety of people, uses)
- data security (restricted rights to view/edit) Students only can manipulate U drive in VIU database.
- Basic analysis is simple
What are some basic analysis methods
Sorting,
Searching,
Querying
What are the generic field types?
Text / string (character based data) - No math
-may contain numbers not used in calculations (ID number)
Numbers
-Integers or Real numbers
Differentiate between precision and scale
Precision is the number of digits. It is independent of decimals, can include “-“ and includes “0 placeholder if a fraction.”
Scale is the # of decimal places
What is the scale and precision of the following numbers 99 32000 0.0012 -123.15
99 - p2 s0
32000 p5 s0
0.0012 p5 s4
-123.15 p6 s2
Can you change the database once you create it in ArcGis?
No, so go big
What are the choices for integer in the number field?
short
long
What are the choices for the real number (decimal) field?
float
double
What field type for
- Stand label (FC 841) - Text
- Stand height (35.6) - Real number + float
- Site index (24) - Integer - short
- area - (12.3) - Real number - float
- area - (123,000) -Integer - long
What are blobs?
Any file type attached
What are the 2 choices for the numbers field type?
- Integer
- Real number (decimal)
How do you determine what field data falls under
- Can i do math with it? If no then it is text/string
- Does it have a decimal? if no, Integer
- Assume that the integer is “long” or the real number is “double”.
How any parts to a query?
3
-field name - top of the table (ex. m3/ha)
-relational operator (=, less than, greater than.)
-value (ex. 400)
sumary ( m3/ha greater than 400 )
What is a complex query?
more than 1 criteria
How do you perform a complex query?
Using the word AND will specify that both criteria must be met
Using OR specifies that only one criteria must be met
Using NOT eliminates criteria
What is a boolean operator?
words like AND, OR and NOT to refine search
What things in GIS utilize database tables?
-attributes organized
-spatial data managed (can’t see it)
spatial data and attribute data are linked
In table relation, differentiate between primary and secondary key.
- Primary key is the ID column that is in the destination table (IN GIS IT IS ALWAYS THE MAP TABLE)
- Secondary key is the outside source table being brought in.
What ar the different relations?
- One to one
- Many to one
- One to many
What does many to one mean?
Many records in the destination table relate to one record in the outside source table.
tables are joined
Can you edit data in the outside source table?
No, because you are not in it.
What does one to many mean?
One record in the data table relates to many
-Relates / Links table (Not joined)
What is the different between join and a link?
A join can be performed with M:1 or 1:1 relations.
A link can be performed with a 1:M relation.
