Homework Help: Questions and Answers: The table below describes the sowing method used for a few vegetables Which field in this table can you define as the primary key?
a) Name
b) Sowing Method
c) Sowing Time
d) Sr. No
Answer
To solve this question, we need to understand which field in the table can be defined as the primary key.
A primary key is a unique identifier for a record in a table. It must contain unique values, meaning no two rows can have the same value for the primary key, and it cannot be null.
Step-by-step analysis of the fields:
a) Name
- Looking at the “Name” field, we see that the “cucumber” appears twice (at Sr. No. 6 and 7). Therefore, this column cannot be the primary key as it does not contain unique values.
b) Sowing Method
- The “Sowing Method” field contains repeated values as well (e.g., “outdoor” appears multiple times), which means it cannot uniquely identify a record. So, this field is not suitable as the primary key.
c) Sowing Time
- Similar to the previous columns, “Sowing Time” also has repeated values (e.g., “March-May” appears at Sr. No. 2 and 5), so it cannot be used as the primary key.
d) Sr. No.
- The “Sr. No.” field contains unique values for each row (from 1 to 7). Since there are no duplicates and each value is unique, this field can be used as the primary key.
Final Answer
Based on the above analysis, the field that can be defined as the primary key is
Correct Option: d) Sr. No.
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