Given a table employees with columns id, name, and department, what will be the effect of creating an index on the department column?Consider the query: SELECT ...

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SQL - Indexes and Query Performance

Given a table employees with columns id, name, and department, what will be the effect of creating an index on the department column?

Consider the query: SELECT * FROM employees WHERE department = 'Sales';

AThe query will run faster by quickly locating 'Sales' rows

BThe query will run slower due to index overhead

CThe query will return no results

DThe index will delete rows not in 'Sales' department

Step-by-Step Solution

Solution:

Step 1: Understand index effect on filtering queries
An index on the department column helps the database find matching rows faster.
Step 2: Analyze the query filtering by department='Sales'
The index allows quick lookup of rows where department equals 'Sales', speeding up the query.
Final Answer:
The query will run faster by quickly locating 'Sales' rows -> Option A
Quick Check:
Index on filter column = faster query [OK]

Quick Trick: Index speeds up WHERE filtering on that column [OK]

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