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SQL – Index
SQL

SQL – Index

A complete SQL resource covering query logic, joins, subqueries, CTEs, window functions, indexing, transactions, DML, database design, and interview preparation.

This platform aggregates top-tier industry insights, web resources, and academic fundamentals, synthesized using advanced AI analysis to streamline your technical interview preparation and conceptual revision.

Revision Guide

Core SQL concepts broken down from theoretical foundations to modern database internals.

  • Part 1: Query Logic & NULL Handling (revision/01-sql-revision) Logical execution order, WHERE vs HAVING, CASE, NULL semantics, aggregates, GROUP BY vs DISTINCT, and pagination.
  • Part 2: Joins, Set Operations & Constraints (revision/02-sql-revision) Join types, self/cross/anti-joins, set operations, double-counting traps, constraints, and join selection.
  • Part 3: Subqueries, CTEs & Window Functions (revision/03-sql-revision) Nested vs correlated subqueries, CTEs, window functions, ANY/ALL, Nth-highest, and duplicate removal.
  • Part 4: Indexing, Transactions & DML (revision/04-sql-revision) Index design, EXPLAIN, SARGable queries, transactions and locking, and the full DML toolset (UPDATE, DELETE, UPSERT).

Placement Essentials

Targeted practice modules designed around high-frequency patterns seen in technical interviews.

  • Top 10 Most Repeated Questions (mock/quiz/top-10/top-10-high-frequency) The absolute essential, high-frequency questions that appear in nearly every technical interview.

Top Coding Challenges

Practice vital foundational to advanced query challenges.

  • SQL Coding Challenges (mock/quiz/sql_coding) Practice vital foundational to intermediate functional query challenges for technical rounds.
  • TCS SQL Coding (mock/quiz/tcs_nqt_sql_coding) Targeted practice questions focusing directly on national qualifier test patterns and criteria.

Top 50 Questions Series

Comprehensive practice tracks covering everything from fundamental rules to advanced SQL engineering challenges.

  • Top 50 - Part 1 (mock/quiz/top-50/top-50-part-1) Part 1 of the most frequently asked core placement and engine definition questions.
  • Top 50 - Part 2 (mock/quiz/top-50/top-50-part-2) Continue practicing essential intermediate operations and multi-table evaluation problems.
  • Top 50 - Part 3 (mock/quiz/top-50/top-50-part-3) Advanced analytical metrics and multi-conditional filtering structures from the Top 50 series.
  • Top 50 - Part 4 (mock/quiz/top-50/top-50-part-4) Final part of the high-frequency assessment list tackling optimization and internal database theory.

Comparison Scenarios

Master nuanced differences that interviewers love to test.

  • Comparison Scenarios - Part 1 (mock/quiz/comparison/comparison-scenarios-part-1) Solve evaluation questions contrasting different system elements and alternative query structures.
  • Comparison Scenarios - Part 2 (mock/quiz/comparison/comparison-scenarios-part-2) More high-yield structural comparisons frequently utilized by interviewers to test depth.
  • Comparison Scenarios - Part 3 (mock/quiz/comparison/comparison-scenarios-part-3) Advanced technical evaluations measuring complex trade-offs between performance profiles and sets.

Scenario & Troubleshooting Questions

Real-world scenarios designed to test applied architecture and diagnostic capabilities.

  • Scenario Questions - Part 1 (mock/quiz/scenario/scenarios-part-1) Practice real-world business case problems and production database environment simulations.
  • Scenario Questions - Part 2 (mock/quiz/scenario/scenarios-part-2) Additional industry scenario-based debugging and data generation tracking puzzles.

Section-wise Q&A

Topic-by-topic interview practice mapped to the SQL syllabus.

My Private Notes

Notes are auto-saved locally to this device.