Key Attribute (Primary Key)
A unique identifier for each record in a GIS attribute table, crucial for data integration, joins, and relational database management.
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What is Key Attribute (Primary Key)?
Every record in a database table or attribute table in a GIS is uniquely identified by a Key Attribute, often known as a Primary Key. By giving each entry a unique value, like an ID number or code, it guarantees that no two records are identical.
Important attributes:
Uniqueness: The primary key column's values must all be distinct.
Non-null: Null (empty) values are not allowed.
Connecting Data: In relational databases, primary keys are utilized to connect related tables via joins or relationships.
Example in GIS:
The City_ID column may be used as the primary key in a table of cities. As a result, GIS software can:
Link the geographic forms of cities to their characteristics (such as area or population).
Use the same ID to do joins with additional datasets.
In conclusion, a primary key is necessary for effective database administration and data integrity, particularly when working with sizable spatial datasets.
Related Keywords
Each record in a database table is uniquely identified by its primary key. Data integrity is maintained by making sure that no two rows have the same value in that column (or group of columns). In relational databases, primary keys are frequently used to create associations between tables since they cannot be null.
A Primary Key in SQL is a column or a set of columns that uniquely identifies each row in a table. It ensures uniqueness and non-null values, meaning no two rows can have the same primary key, and it cannot be left empty. Primary keys are essential for maintaining data integrity and are often used to establish relationships between tables in a database.
Each entry in a database table is uniquely identified by its primary key, which makes sure that no duplicate entries are present in that column. In order to create a relationship between two tables and preserve referential integrity, a foreign key is a column in one table that connects to the primary key of another table. In essence, the foreign key defines connections, and the main key defines uniqueness.
A Primary Key in SQL uniquely identifies each row and cannot be NULL. CREATE TABLE Employees (
EmployeeID INT PRIMARY KEY,
Name VARCHAR(50)
);