Slow Query Log — SQL Technical Interview Questions & Answers

Slow Query Log

Slow Query Log

  • Slow Query Log is a MySQL topic you learn with one small college example — a students table with roll, name, marks. Say what Slow Query Log does in one sentence, then write the shortest SQL that shows it.
  • Pattern: USE college; then a CREATE/SELECT/UPDATE that needs Slow Query Log. If it is a function, SELECT it on one column. If it is DDL, run SHOW / DESCRIBE after so you can see the change.
  • Trap: only reciting the heading Slow Query Log with no SQL. Interviewers ask you to type. Another trap: mixing this up with a neighbouring command (DELETE vs TRUNCATE vs DROP, WHERE vs HAVING, JOIN vs UNION).
  • Keep the example on paper: two or three rows. Change one value. Predict the result before you run it.
  • On the example next to this theory: Slow Query Log — sELECT projects columns; WHERE filters; ORDER BY sorts.

Technical Interview Tip: What is Slow Query Log? One sentence + one tiny SQL on students.

Code Examples for Slow Query Log

Slow Query Log — sample query

CREATE TABLE employees (id INTEGER PRIMARY KEY, name TEXT, dept TEXT, salary INTEGER);
INSERT INTO employees VALUES
  (1, 'Asha', 'Eng', 70000),
  (2, 'Ravi', 'Eng', 65000),
  (3, 'Neha', 'HR', 50000);
SELECT name, salary FROM employees WHERE dept = 'Eng' ORDER BY salary DESC;

Slow Query Log — sELECT projects columns; WHERE filters; ORDER BY sorts.

How to Explain Slow Query Log to an Interviewer

What is Slow Query Log?

A MySQL idea used with tables/queries Show one short SQL

Give an example.

students table SQL that uses Slow Query Log

What mistake do beginners make?

Name only, no SQL Mixing nearby commands