You will get Write, optimise and debug your SQL queries and database
Project details
You'll get clean, well-tested SQL that returns exactly what you need — clearly documented so you or your team can understand and maintain it later. I'm a Data Engineer who works with SQL every day across Snowflake, PostgreSQL and standard SQL: building reporting queries, fixing slow ones, and reviewing database structure. I get your requirements right first, then deliver queries that are accurate, efficient and easy to follow — with plain-English notes on what each one does and any optimisation I've made. I care about clear communication and reliable, on-time delivery, and I'll always flag anything that could work better. Whether it's one tricky query, a full reporting layer, or a slow query that needs speeding up, I'll make your data easy to trust and work with.
Database Type
PostgreSQL, MongoDBWhat's included
| Service Tiers |
Starter
$40
|
Standard
$90
|
Advanced
$180
|
|---|---|---|---|
| Delivery Time | 2 days | 4 days | 7 days |
Number of Revisions | 1 | 2 | 3 |
Number of Queries | 3 | 8 | 20 |
Query Debugging | |||
Query Optimization | |||
Query Scheduling | - | - | |
Query Analysis | - | ||
Source Code |
Frequently asked questions
About Donald
Data Engineer | SQL, Python, Snowflake, AWS & Power BI
London, United Kingdom - 11:22 pm local time
I'm a UK-based Data Engineer who designs and builds end-to-end data pipelines, cloud data warehouses and reporting solutions using SQL, Python, Snowflake, dbt, AWS, Airbyte and Power BI.
Recent projects I've built:
- Retailio — an end-to-end cloud pipeline ingesting 10,000+ product records and 9,900+ sales records into Snowflake for analytics and reporting.
- Bridgestone Retail — a dimensional Snowflake + dbt data warehouse feeding Power BI dashboards for sales reporting.
- NorthBridge IMS — reporting pipelines and a warehouse model for incident data (tickets, clients, agents and SLAs).
- A self-service, metadata-driven ETL framework in Python with pipeline monitoring and reusable ingestion logic.
I specialise in ETL/ELT development, dimensional data modelling, data cleaning and validation, and building dashboards stakeholders actually use.
Services I offer:
- SQL development & query optimisation
- Python data engineering & automation
- ETL & ELT pipelines
- Snowflake data warehousing
- dbt data modelling
- AWS / cloud ingestion with Airbyte
- Power BI dashboards
- Data cleaning, validation & CSV/Excel processing
Whether you need a pipeline built, data cleaned, or a dashboard that finally makes sense, I deliver well-documented, maintainable solutions and clear communication throughout.
Message me with what you're working on and I'll tell you honestly how I can help.
Steps for completing your project
After purchasing the project, send requirements so Donald can start the project.
Delivery time starts when Donald receives requirements from you.
Donald works on your project following the steps below.
Revisions may occur after the delivery date.
Review your data and requirements
I review your schema, sample data and goals, then confirm the scope and raise any questions before I start.
Write and optimise the SQL
I write clean, well-structured queries (or optimise existing ones), testing the results against your requirements.