
SQL Experts in Dortmund
to turn complex data into reliable systems with fast, precise AI matchingHire experts who design relational databases, optimize queries and build dependable reporting pipelines with SQL, PostgreSQL, Microsoft SQL Server and cloud data platforms. FRATCH matches you quickly with vetted, available freelancers suited to your project.
Meet FRATCH Experts in Dortmund, who have recently used SQL
Muhammad Y.
Last position:
SynQ × AutoStore
- Enterprise WMS customisation for Albert Heijn and EDEKA.
- Owned end-to-end test planning, automation, and performance validation for logistics automation software serving high-volume grocery warehouse operations.
Yasin Y.
Last position:
Enterprise Architect at Bundesagentur für Arbeit
Task:
- Design and build a proof of concept (PoC) for a future-proof virtualization platform, taking secure system architectures into account
- Assess the current state of existing infrastructures and develop selection and evaluation criteria for the right OS virtualization platform
- Carry out the requirements analysis and then create and prioritize tickets in the ticket system
- Complete and continuously update a tool evaluation matrix based on PoC results
- Support team knowledge building through clear documentation of the approach and results in Confluence
- Enterprise analysis of existing hardware (creating different BoMs)
Technologies: Vmware, Vmware Aria Operations, Osism, Canonical OpenStack, FishOs, Linux, Terraform, Ansible, Confluence, Alma
Arkadius S.
Last position:
AWS Pricing Platform / API & Integration Architecture at Porsche Digital
Development and evolutionary further development of a highly available, cloud-native microservice and integration architecture for dealer and retail processes in the Porsche Car Configurator.
Responsibilities
- Development of Java-/Kotlin-based backend, API, and integration components (Spring Boot)
- Integration of internal and external systems via REST/OpenAPI, GraphQL, Apache Kafka, and AWS SQS (synchronous and asynchronous)
- Implementation of stable, high-performance communication and data flows in a cloud-native platform architecture
- Processing of structured data formats (JSON, Protobuf, GraphQL schemas) based on existing API patterns
- Performance optimization of distributed microservices with reduced response times and higher operational stability
- Technical tests (unit, integration, and API tests) as well as error analysis in production-like environments
- AWS Infrastructure as Code with Terraform and AWS CDK
- CI/CD automation (build, test, and deployment pipelines) with GitHub Actions
- AI-supported feature implementation (GitHub Copilot Agent)
Label: Kotlin, Java 25, Spring Boot 4, Protobuf, TypeScript, AWS, Terraform, CDK, Apache Kafka, AWS SQS, REST/OpenAPI, GraphQL, JSON, PostgreSQL, Docker, GitHub Actions, Maven, Gradle, JUnit, Mockito, Testcontainers
Nemanja M.
Last position:
AI Engineer / Senior Backend Engineer at Intelycx
Manufacturing intelligence platform with enterprise workflows, RAG, real-time AI assistant features, and multi-repository backend architecture.
- Built and extended production AI/backend services with Django, DRF, FastAPI, GraphQL, Celery, PostgreSQL, MySQL, Redis, and WebSockets across a modular multi-repository platform.
- Contributed to ARIS V2, a real-time manufacturing AI assistant using LangChain, LangGraph, MCP tool orchestration, planning/execution flows, OpenAI, AWS Bedrock, Qdrant, and Elasticsearch/OpenSearch-backed retrieval.
- Supported rollout expansion from ARIS V1 in 4 of 17 client production plants to ARIS V2 currently active in 13 of 17 plants, increasing real-world deployment coverage to more than 50% of the client footprint.
- Worked on document-grounded RAG functionality including ingestion, OCR, chunking, embeddings, indexing, retrieval, reranking, and grounded answer generation for industrial workflows.
Stack: Python, Django, DRF, FastAPI, LangChain, LangGraph, GraphQL, Celery, WebSockets, OpenAI, AWS Bedrock, Qdrant, Elasticsearch/OpenSearch, PostgreSQL, MySQL, Redis, Docker.
Manuel K.
Last position:
.NET Developer, SAP Business One Consultant at Own Projects
- DTO class generator: In-house development of a tool for the automatic generation of classes, functions, and methods for use in .NET Core projects based on SAP Business One Service Layer metadata
- E-invoice import add-on: Development of a SAP Business One add-on / coresuite module for the automated import of ZUGFeRD e-invoices as incoming invoices – with configurable mapping to flexibly control the import logic across four mapping types (DIRECT, SQL, FIXED, EXPR). The add-on is available as a licensed product for SAP Business One customers.
Stack: SAP Business One, SAP Business One Service Layer, coresuite Country Package, C#
Kersten L.
Last position:
Lead Architect / Lead Developer at Bettles: Sports Betting Platform
- Complete greenfield rebuild across the whole stack — built AI-native: backend in Go and NestJS, PostgreSQL (CNPG) on K3s with GitOps/Terraform; frontend on Angular 22, zoneless.
- Orchestrated coding agents (e.g. Claude Code, Cursor) across the entire lifecycle — architecture, implementation, testing, reviews, documentation — driven by Specification-Driven Development (SDD).
- “Bruno” — LLM commentator persona backed by RAG and MCP for a personality that stays consistent across all generations (match previews, post-match reports, his own virtual bets).
Angular 22 (zoneless, without Zone.js), Claude Code, Claude Code Skills, CNPG, Cursor, Design Tokens (Spec for Code), Docker, Gherkin, Git, GitLab, GitOps, Go, Google Gemini, Grafana, Hetzner Cloud, K3s, Keycloak, Kubernetes, Lighthouse, LLM Integration, Model Context Protocol (MCP), NestJS, Node.js, NPM, Playwright, PostgreSQL, Prometheus, RAG, REST, Specification-Driven Development (SDD), Structured Outputs, Terraform, TypeScript, Vitest
Diego E.
Last position:
RPG Software Developer from RPG III to Free Format
- Development of software and system support for RPG development.
- Development, optimization and maintenance of programs in RPG (RPG II to ILE Free Format).
- Performing integration tasks, data management as well as applying and managing system updates.
- User support and training to ensure smooth system operation.
Jens S.
Last position:
Network Technology at ISP, Internet Service Provider, BGP Peering
- Optimization of the transmission media of the data links in the Ruhr area
- Configuration/expansion of switches and routers for an autonomous system AS
- Improve the network protocols used Layer 2/3 (OSI model), RSTP, broadcast, etc.
- Laying cables, crimping, antennas, routers, switches
- Maintenance, expansion, selection and prioritization of troubleshooting measures for network monitoring (PRTG, The Dude)
- Organization and new connection of another BGP peering, data center, NGN fiber optic
- VPN IPSec site connections for 6 sites with PFSense, Fritzbox
- Configuration of WLAN devices (Mikrotik, UBNT
Label: TCP/IP, VLAN, BGP, OSPF, MPLS, VPLS, routing protocols, WLAN, EoIP, PPPoE, routing, SNMP, DHCP, DNS, NAT, native IP, VLAN, Ethernet, VoIP., switches and routers from: Nortel, Cisco, MikroTik, UBNT., network management systems: The Dude, PRTG, UISP
Adnan U.
Last position:
Independent AI & Automation Projects
- Development of an automated job-scouting workflow for the aggregation and LLM-based evaluation of job postings from RSS feeds and APIs.
- Development of a Telegram bot for voice and text messages, featuring LLM-supported processing, summarization, and structured JSON output.
- Implementation of a personal task-planning assistant using n8n, OpenRouter, and Supabase for automated daily and knowledge organization.
- Development of LLM chatbots for structured knowledge retrieval utilizing prompt constraints, guardrails, and forced output formats.
Rainer P.
Last position:
Senior Controller at Stahlhandel-Servicecenter Bönen
- Controlling project work: implementation of customer quotation calculation and development of a trading and forward calculation for sales
- Development of a cost of goods manufactured calculator
- Theoretical design and practical implementation: temporary Excel-based solution introduced quickly; embedding into INFOR LN and creation of the requirements specification
- Majority of project management using modern tools (Loop, Jira, Excel, PowerPoint)
- Regular reporting on quotes submitted (contribution margin 1 and full cost coverage) and comparison with post-calculation
Dany-Armand D.
Last position:
Senior Data Scientist at ibg NDT GmbH
- Investigate the relationship between Eddy Current Testing (ECT) signals and microstructural properties
- Detect latent patterns in ECT data that reflect intrinsic material characteristics
- Develop and validate predictive models for microstructural classification and quantification, using hardness and case depth as benchmarks
- Apply Bayesian Structural Equation Modeling for advanced data analysis
Patrik G.
Last position:
Technical Lead Conversational AI at CANCOM
- Technical lead of a team developing agentic chatbot solutions (React, TypeScript, Python, FastAPI)
- Architecture design for multi-LLM dialog systems - focus on maintainability, UX, and autonomous execution
- Stakeholder alignment, CI/CD processes, and AI integration at enterprise level
Thomas G.
Last position:
Senior .NET / Cloud Engineer at Freelance
Building an observability and alerting solution for Business Central Job Queue monitoring
- Built a central monitoring solution to track the Business Central Job Queue in a multi-organization environment in Azure DevOps
- Integrated Azure Application Insights and Log Analytics for structured collection and analysis of job runtimes and error events
- Developed KQL queries for targeted analysis of failed jobs and detection of error patterns
- Connected Grafana and Power BI to visualize operational metrics and job status in real time
- Implemented an automated alerting workflow with Power Automate – when a job fails, a notification email is sent immediately
- Ensured transparency about the state of productive background processes during live operations
Result: Full transparency over failed Business Central jobs · Clear reduction in response time through automated email alerting · Stable foundation for proactive operation of productive background processes
Technologies: Azure DevOps | Application Insights | Log Analytics | KQL | Grafana | Power Automate | Power BI | Business Central | Azure Monitor
Damian K.
Last position:
Independent advisory
- Valuation support; analysis of assets, ownership/intercompany structures, reporting, and asset-transfer issues
Rafael K.
Last position:
Senior Android Developer / Team-Lead at IBM Deutschland
- Further development and release support for a white-label ePA component for health insurance companies
- Technologies: Android (Kotlin), Kotlin Multiplatform, Coroutines, Jetpack Compose, MVVM, StateFlow, Gradle, ProGuard
Discover over 15,000 top freelancers
Statistics of experts using SQL
Aggregated from the professional profiles of matched freelancers.
Experience
20 years (Germany: 19 years)

Position duration
2 years (Germany: 5.1 years)

Positions per freelancer
14 (Germany: 12)

Top business areas
Information Technology, Product Development, Project Management

Top industries
Information Technology, Manufacturing, Banking and Finance

Certification focus areas
Information Technology, Quality Assurance, Product Development
Bachelor's degree or higher
86% (Germany: 90%)
Master's degree or higher
57% (Germany: 60%)
Doctorate
11% (Germany: 9%)

Certifications per freelancer
3

Most common languages
German, English, Spanish

Speak two or more languages
100% (Germany: 97%)
Based on our profile pool as of 19 Sep 2026.
Daily rate distribution
The chart shows how the daily rates of freelancers in this technology in Dortmund are distributed, based on recent contracts on our platform. Each bar covers a rate range — its height shows how many freelancers charge within that range.
Average rates of experts in Dortmund using SQL
Rates are based on recent contracts and do not include FRATCH margin.
The average daily rate is the mean of all daily rates from recent contracts of comparable freelancers on our platform.
The median daily rate is the middle value of all daily rates — half of comparable freelancers charge less, half charge more. Unlike the average, it is barely affected by outliers.
Calculated based on our freelancers’ daily rates as of 19 Sep 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
SQL experts industry focus
See which industries our matched freelancers work in most often — every figure is calculated live from the freelancers on FRATCH.
- Information Technology (80%)
- Manufacturing (51%)
- Banking and Finance (49%)
- Retail (49%)
- Education (40%)
- Healthcare (40%)
- Professional Services (37%)
- Automotive (31%)
Please note that freelancers can work across multiple industries, so percentages overlap.
About the technology
What SQL does
SQL is the standard language for storing, querying and transforming structured data in relational databases. Companies use it to power business applications, customer records, financial systems, inventory workflows and operational reporting. Strong SQL design keeps data accurate, accessible and consistent as systems grow.
Core database work
SQL professionals model tables and relationships, define constraints, write queries and create procedures for repeatable data operations. They work with PostgreSQL, MySQL, Microsoft SQL Server, Oracle Database and cloud services such as Amazon Redshift, Google BigQuery and Snowflake. Their work often includes:
- Designing schemas for transactional applications
- Tuning slow queries and indexing strategies
- Building views, reports and data exports
- Migrating data between database systems
Where companies use it
SQL appears in nearly every sector that depends on reliable business data. It supports ecommerce catalogs, manufacturing operations, logistics planning, healthcare records, banking workflows and public administration systems. In Dortmund, specialists may contribute to industrial, logistics and service organizations that need secure access to operational information.
When freelance expertise helps
Companies bring in freelance SQL professionals when a database has become difficult to maintain, reporting takes too long or a migration carries significant operational risk. They can extend an existing team during a delivery phase, investigate production issues or establish a clean data foundation for a new application. Typical assignments include:
- Restructuring schemas without disrupting live services
- Recovering performance in high-use databases
- Validating data quality and migration results
- Connecting SQL systems to analytics tools
Skills around SQL
Effective SQL work depends on more than writing queries. Specialists understand normalization, transactions, locking, execution plans, indexing, permissions and backup strategies. They may also use Python, Java, C#, dbt, Airflow, Power BI or Tableau, depending on whether the project focuses on applications, integration or analytics.
What strong specialists deliver
The best professionals clarify the business meaning of data before changing a query or schema. They produce readable SQL, document important decisions and test results against realistic data volumes. They also explain trade-offs between performance, maintainability and security, then leave behind monitoring, migration scripts and documentation that the internal team can use.
Remote collaboration works well for many SQL assignments when access, environments and responsibilities are clearly defined. For Dortmund-based organizations, occasional on-site workshops can help align database work with local product, operations and reporting teams.
Frequently asked questions
Curious about SQL? Here are the answers that come up again and again.
SQL is used to store, retrieve, update and analyze structured data in relational databases. It supports functions such as customer management, order processing, inventory control, invoicing and internal reporting.
SQL databases organize information into related tables and provide strong rules for consistency, which suits transactions and structured business data. NoSQL systems can offer more flexible models or scaling patterns for certain workloads, so the right choice depends on data relationships, access patterns and operational needs.
A strong SQL specialist may also understand database administration, data modeling, cloud infrastructure and version-controlled deployment. Python, dbt, Airflow, Power BI or Tableau can be valuable when the work includes pipelines, automation or analytics.
The required level depends on the risk and scope of the assignment. A reporting task may need strong query and data-validation skills, while a live migration or performance investigation calls for proven knowledge of transactions, execution plans, backups and recovery procedures.
Yes, many SQL assignments can be completed remotely through secure access, shared documentation and controlled deployment processes. On-site workshops in Dortmund can still be useful when specialists need to map operational processes with product, finance or data teams.
Ask the SQL professional to explain how they approach data modeling, query performance, testing and rollback planning. Review whether their queries are readable, their assumptions are documented and their changes protect data integrity rather than solving only the visible symptom.
SQL is the language, while PostgreSQL is a relational database system that implements SQL and adds its own features. A specialist should know standard SQL as well as the indexing, extensions, transaction behavior and tooling relevant to the chosen database.
Before working with SQL, clarify the database engine, data sensitivity, access method, deployment process and definition of success. It is also important to understand whether the assignment concerns application behavior, reporting, migration, performance or long-term database ownership.
The average hourly rate of freelancers in Dortmund, Germany who have used SQL in their recent projects is 90 €, which corresponds to a daily rate of about 720 € based on an 8-hour working day.
Of the freelancers in Dortmund, Germany who have used SQL in their recent projects, 86% hold at least a Bachelor's degree, 57% hold at least a Master's degree, and 11% hold a doctorate.
On average, freelancers in Dortmund, Germany who have used SQL in their recent projects have 20 years of professional experience, with a single engagement typically lasting around 2 years.
The most common languages among freelancers in Dortmund, Germany who have used SQL in their recent projects are German (100%), English (100%), and Spanish (20%).
The most common industries among freelancers in Dortmund, Germany who have used SQL in their recent projects are Information Technology (80%), Manufacturing (51%), and Banking and Finance (49%).
The most common business areas among freelancers in Dortmund, Germany who have used SQL in their recent projects are Information Technology (86%), Product Development (74%), and Project Management (63%).
Main locations of FRATCH Experts, who have recently used SQL
Our freelancers and interim experts are at home across the DACH region — available on-site in the major business hubs or fully remote. Choose a location to discover matched specialists, local market insights and up-to-date availability.
Request a free demo
Get in touch with the FRATCH team and we will get back to you within 4 hours.
Would you rather directly get in touch?
We always have the time for a call or email!

Berlin
Hamburg
Munich
Cologne
Frankfurt
Stuttgart
Dusseldorf
Leipzig
Essen
Bremen
Dresden
Hanover
Nuremberg