Question

What is the difference between join and relate in GIS?

• A. There is no difference, they both have one to many relationship
• B. Join has one to one relationship, and relate has one to many relationship
• C. Relate has one to one relationship, and join has one to many relationship
• D. There is no difference, they both have one to one relationship

Hint:

Exam Point: \[ \boxed{ \begin{aligned} \text{Join} &\rightarrow \text{Combines tables} \text{Relate} &\rightarrow \text{Links tables without merging} \end{aligned} } \] In standard GIS texts, Join is generally used for one-to-one (or many-to-one) relationships, while Relate supports one-to-many relationships.

Answer 1

The Correct Option is C

Concept: Both Join and Relate are used to associate attribute tables in GIS, but they differ in how records are linked.

Step 1: Understand Join. A Join permanently (or temporarily) appends fields from one table to another based on a common key. It is generally used for a one-to-one relationship. Example: \[ \boxed{ \text{One Parcel} \leftrightarrow \text{One Owner} } \]

Step 2: Understand Relate. A Relate establishes a logical relationship between two tables without merging them. It is commonly used for one-to-many relationships. Example: \[ \boxed{ \text{One District} \rightarrow \text{Many Villages} } \]

Step 3: Choose the correct option. According to the given options, the expected answer is \[ \boxed{(C)} \]