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WorkshopRuns on requestData & databasesPostgreSQLSQLpsql

SQL for Application Developers

Two hands-on days on a database large enough to hurt — window functions execution plans index design transaction isolation and the query patterns that quietly destroy an application under load. You leave having taken a nine-second query under fifty milliseconds.

Fee
₹2,700
Duration
2 days · 16 hours
Each day
09:00 – 17:00
Mode
Offline / Online
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Designed for

  • Application developers whose SQL was learned from an ORM
  • Backend engineers whose queries were fine until the data grew
  • Data analysts who write SQL daily and have never read a query plan
  • QA and support engineers who need to investigate data problems
  • Anyone preparing for interviews where SQL is tested properly

What to bring

  • A laptop able to run PostgreSQL locally or in Docker
  • Basic SELECT and WHERE experience — we start from the mental model
  • Any programming language for the application-side sessions

What you walk away with

A worked notebook of every query you wrote over two days including the slow versions the plans that explained them and the rewrites that fixed them — plus a query review checklist and the seeded dataset to keep practising on.

Outcomes

What you will be able to do

  1. 01Predict what a query returns by reasoning about the logical order of operations
  2. 02Explain why a WHERE clause cannot see a SELECT alias and why NULL breaks equality
  3. 03Write joins that return the right number of rows and spot an accidental cartesian product
  4. 04Replace application loops and repeated round trips with a single set-based query
View all 10 outcomes
  • Use window functions for ranking running totals period comparisons and deduplication
  • Read an EXPLAIN ANALYZE plan and say why the database chose that path
  • Design a composite index with the columns in the right order and prove it was used
  • Explain why an index was ignored and fix the query rather than adding another index
  • Choose an isolation level deliberately and reproduce a lost update then prevent it
  • Fix an N plus one and replace offset pagination with keyset pagination

The two days

10 hands-on sessions

2 days · 16 hours

  1. Foundation
  2. Intermediate
  3. Advanced
  1. FoundationDay 1 · 09:00 – 10:15

    Thinking in sets rather than loops

    • the relational mental model
    • logical order of operations from FROM through to LIMIT
    • why WHERE cannot see a SELECT alias
    • NULL and three-valued logic
    • IS DISTINCT FROM
    • COALESCE and NULLIF
    • DISTINCT and its cost
    • ORDER BY without determinism

    What you will build

    Three application loops rewritten as single queries — with the round trips counted before and after so the difference is measured rather than claimed.

    Module 1

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