🧠 MASTER SQL INTERVIEW PATTERN
Almost all queries follow this one mental flow:
SELECT → FROM → WHERE → GROUP BY → HAVING → ORDER BY → LIMIT
SELECT → columns / functions (SUM, COUNT, AVG)
FROM → table
WHERE → row filtering (LIKE, BETWEEN, IN, =)
GROUP BY → grouping
HAVING → group filtering
ORDER BY → sorting
LIMIT → restrict rows
Remember this sentence:
“Smart Friends Wear Green Hats On Lunch.”
S → SELECT
F → FROM
W → WHERE
G → GROUP BY
H → HAVING
O → ORDER BY
L → LIMIT
Most interview queries are just variations of this pipeline.
🔥 PATTERN 1 — RANKING / TOP VALUES
Questions:
1️⃣ Nth highest salary
2️⃣ Second highest salary
12️⃣ Top N records
16️⃣ Max salary employee
Pattern
ORDER BY column DESC
LIMIT N
Example
SELECT *
FROM employees
ORDER BY salary DESC
LIMIT 3;
Memory trick
Ranking → ORDER BY + LIMIT
🔥 PATTERN 2 — DUPLICATE DETECTION
Questions:
3️⃣ duplicate names
11️⃣ duplicate records
Pattern
GROUP BY column
HAVING COUNT(*) > 1
Example
SELECT name, COUNT(*)
FROM employees
GROUP BY name
HAVING COUNT(*) > 1;
Memory trick
Duplicates → GROUP BY + HAVING
🔥 PATTERN 3 — FILTERING DATA
Questions:
7️⃣ names starting with A
9️⃣ name ending with A
10️⃣ salary between range
Pattern
WHERE condition
Examples
WHERE name LIKE 'A%'
WHERE salary BETWEEN 10000 AND 50000
Memory trick
Filtering → WHERE
🔥 PATTERN 4 — COUNT / AGGREGATION
Questions:
8️⃣ number of employees in department
Pattern
SELECT COUNT(*)
FROM table
WHERE condition
Example
SELECT COUNT(*)
FROM employees
WHERE department_name='ABC';
Memory trick
Counting → COUNT + WHERE
🔥 PATTERN 5 — TABLE COPYING
Questions:
5️⃣ create empty table
21️⃣ same structure table
Pattern
SELECT * INTO new_table
FROM old_table
WHERE 1=0
Memory trick
Copy structure → WHERE FALSE
🔥 PATTERN 6 — JOINS
Questions:
13️⃣ employees under manager
22️⃣ users with fewer orders
23️⃣ salary > 15000 using 2 tables
Pattern
SELECT columns
FROM table1
JOIN table2
ON condition
Example
SELECT e.name, s.salary
FROM employees e
JOIN salaries s
ON e.employee_id = s.employee_id;
Memory trick
Multiple tables → JOIN
🔥 PATTERN 7 — SET OPERATIONS
Questions:
19️⃣ UNION
20️⃣ INTERSECT
Pattern
SELECT ...
UNION
SELECT ...
Memory trick
Combining results → UNION
🔥 PATTERN 8 — DATE QUERIES
Question:
15️⃣ employees hired in last 8 months
Pattern
WHERE date >= CURRENT_DATE - INTERVAL
Example
WHERE hire_date >= CURDATE() - INTERVAL 8 MONTH;
Memory trick
Time filtering → INTERVAL
🧠 THE 7 SQL SUPER PATTERNS
If you remember this table, you can solve 90% SQL interview questions.
| Pattern | SQL Keyword | Used For |
|---|---|---|
| Ranking | ORDER BY + LIMIT | highest salary |
| Duplicate detection | GROUP BY + HAVING | duplicates |
| Filtering | WHERE | conditions |
| Aggregation | COUNT / SUM | totals |
| Table copy | SELECT INTO | structure |
| Multi-table | JOIN | relations |
| Result merge | UNION | combine |
⭐ INTERVIEW RECALL FRAMEWORK
When interviewer asks a query, think in this order:
1 What data? → SELECT
2 From where? → FROM
3 Any filter? → WHERE
4 Any grouping? → GROUP BY
5 Any group filter? → HAVING
6 Any sorting? → ORDER BY
7 Any limit? → LIMIT
This reconstructs the query mentally.
🚀 ULTIMATE 10-SECOND SQL RECALL METHOD
Remember FROGS-HL:
F → FROM
R → WHERE
O → ORDER BY
G → GROUP BY
S → SELECT
H → HAVING
L → LIMIT
⭐ FINAL INSIGHT (Important)
After analyzing your images:
Out of 23 questions
| Category | Count |
|---|---|
| Filtering | 6 |
| Ranking | 4 |
| Aggregation | 3 |
| Joins | 3 |
| Duplicates | 2 |
| Table copy | 2 |
| Set operations | 2 |
| Date queries | 1 |
So interviewers mostly test:
Filtering + Ranking + Aggregation
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