Join type selection directly affects which rows appear in a result set, which is critical when building reports in PostgreSQL or Infosys data platforms. A wrong join can silently exclude records or introduce unexpected NULL values.
You are asked to explain the difference between INNER JOIN, LEFT JOIN, and RIGHT JOIN. Describe which rows each join returns, how unmatched rows are handled, and how the result changes when one table has records with no match in the other table.
Use a simple reporting example such as employees and departments, or customers and orders, to illustrate your explanation. You should also clarify whether LEFT JOIN and RIGHT JOIN are fundamentally different or just mirror images of each other.
The interviewer expects a clear conceptual explanation, not a complex query. Focus on row inclusion logic, NULL behavior, and when you would choose each join type in practice.
Join type selection directly affects which rows appear in a result set, which is critical when building reports in PostgreSQL or Infosys data platforms. A wrong join can silently exclude records or introduce unexpected NULL values.
You are asked to explain the difference between INNER JOIN, LEFT JOIN, and RIGHT JOIN. Describe which rows each join returns, how unmatched rows are handled, and how the result changes when one table has records with no match in the other table.
Use a simple reporting example such as employees and departments, or customers and orders, to illustrate your explanation. You should also clarify whether LEFT JOIN and RIGHT JOIN are fundamentally different or just mirror images of each other.
The interviewer expects a clear conceptual explanation, not a complex query. Focus on row inclusion logic, NULL behavior, and when you would choose each join type in practice.
