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SQL Experts in Cologne

in minutes from over 15,000 CVs with the power of AI

Hire experts who design clean schemas, write reliable queries, and tune databases for reporting, APIs, and business apps. Get fast, precise matching with vetted, available freelancers who can work remotely or on site in Cologne.

Meet FRATCH Experts in Cologne, who have recently used SQL

Verified expert

Burhan Dinler

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Experienced IT and AI Architect

Niederkassel
Burhan Dinler

Last position:

Enterprise Architect & Solution Architect at DB Netz AG

With project PRIZMA, DB will modernize its infrastructure on the one hand, and develop a fail-safe IT landscape on the other hand, which can be restored quickly and securely in case of a disaster.

  • Capture current architectures of existing systems as well as methodical consulting and development of target architectures
  • Deepen and maintain the building plan / target IT landscape
  • Implement technical architecture concepts & architecture descriptions
  • Implement migration concepts for updating and further developing the platform and information systems
  • Assess submitted improvement suggestions as part of the project
  • Capability management: identify capability gaps, develop target visions, and support transformation planning within the enterprise architecture.
  • Create a compatibility matrix of the components in use and compare dependencies of specific versions
  • Create an IT concept for extending the platform with the following topics: hardware and software requirements, security, licensing, high availability, load balancing, backup & recovery, update strategy, monitoring integration, etc.
  • Coordinate with business architects as well as technical architects from the cross-functional architecture area of the PRISMA program for the topics (backup, Active Directory, monitoring, Citrix, and business applications ...)
  • Status meetings and alignment of project planning with the Release Train Engineer / Project Manager
  • Advise the Release Train Engineer / Project Manager in identifying project risks
  • Advise the System Architect Engineers in steering the implementation of the concept
  • Implement the IT concept
  • Document the infrastructure

Label: MS Project, LINUX, Windows, ORACLE, Java, REST, SharePoint, Microsoft Exchange, UML, Enterprise Architect, BPMN, AZURE, AWS, V-MODEL, Micro Service, VisualStudio, SAP S/4HANA, SCRUM(SAFE), ESB (TIBCO), Python, Innovator, LeanIX (TOGAF), Ansible, Ansible Tower, Ansible Automation, ROBOT, SpringBoot

Verified expert

Henning Uiterwyk

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Senior Expert Data Governance, Master Data Quality and Data Migration

Leichlingen (Rheinland)
Henning Uiterwyk

Last position:

Senior Expert Data Governance, Master Data Quality and Data Migration at E.ON

  • Planning and implementation of a migration strategy for master and transaction data for the continuous loading of a cloud-independent database
  • Creation and pilot implementation of a company-wide Business Data Model for customers, suppliers, contracts, products, prices, consumption, invoices, and dunning
  • Concept and consulting for a Data Governance Framework incl. definition of committees, roles, processes, and metadata model
  • Operationalization of the Data Governance Framework with definition of data standards
  • Sub-project management in two pilot projects (PoCs) for Data Governance systems (ErwinDIS and Atlan)
  • Training and coaching the data team in migration, data quality, and data modeling
Verified expert

Markus Blohm

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Consultant, Technical Project Manager

Bergheim
Markus Blohm

Last position:

Consultant, Technical Project Manager at Lanxess

  • Project: ESU Windows and SQL Server consolidation / Configuration Management in ServiceNow
  • Creation of an as-is analysis of all servers worldwide
  • Creation of an as-is analysis of all SQL servers worldwide
  • Creation of requirements analyses for SQL and server migrations
  • Coordination of requirements with partners for migrations to Hyper-V (on-premises) or Azure Cloud
  • Moderation of jour fixe meetings
  • Creation of roadmaps and solution models for server migrations
  • Setup of test scenarios
  • Moderation of workshops for the introduction of a Global Admin Team
  • Creation of data models (CMDB) in ServiceNow
  • Conducting workshops for the CMDB data model
  • Creation of solution models for the CMDB
  • Creation of seamless configuration and work documentation for the CMDB
  • Creation of reports for license management
  • Creation of KPIs for data quality in ServiceNow
  • Creation of a service catalog
  • Moderation of workshops for creating service requests
  • Interface between needs analysis and ServiceNow development team
  • Systems used: Windows 7, Windows 10, Microsoft Office 365/2010, Windows Server 20xx, SQL Server 20xx, SharePoint, Azure Cloud, Hyper-V, ServiceNow, various tools
Verified expert

Rafael De Mestre Gebauer

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Project Manager Modern Workplace

Cologne
Rafael De Mestre Gebauer

Last position:

Project Lead Automation at Textile industry

Analysis and optimization of end-to-end processes in different business areas such as sales, procurement, order processing and logistics. Redesign of the ERP. Identification of optimization potential, especially in areas with media breaks and manual tasks, as well as creation of a prioritized transformation roadmap with clear business cases and implementation recommendations. Management of automation initiatives. RPA at the production site in China. Evaluation and introduction of relevant AI use cases as well as building basic AI competence in the organization. Training internal employees of the project team and supporting them in the transformation process to develop a continuous improvement culture. Close collaboration with IT and external implementation partners, reporting to senior management.

Main tasks and achievements:

  • Analysis of business processes and design of automated processes
  • Training and support for employees in China and Germany
  • 20% cost savings in logistics
  • Regular status reports to management
Verified expert

Alexander Bromberg

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Senior Data Engineer

Köln
Alexander Bromberg

Last position:

Senior Data Engineer at RWE AG

Architected and maintained data products for renewable energy operations, covering wind turbine, grid-meter, and weather data. Built scalable ETL/ELT pipelines in Azure Databricks using Delta Lake (bronze/silver/gold layers) and processed data in various formats, including structured and semi-structured data. Contributed to a data quality framework supporting table and column documentation, outlier detection, and completeness metrics across all datasets within a data product. In addition, implemented a DORA KPI Databricks dashboard used across all data products. Optimized CI/CD processes in Azure DevOps to streamline deployment across development, test, and production environments.

Technology stack: Azure Databricks, PySpark, SQL, Delta Lake, Unity Catalog, Azure Data Lake, APIs, Dremio, Azure DevOps, YAML, Git, Databricks Workflows, Application Insights, Terraform, OpenAI API, Codex, LLM-assisted workflows

Verified expert

Marc Smyk

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Fullstack Engineer | Java & Spring Boot | Angular | System Integration

Leverkusen
Marc Smyk

Last position:

Fullstack Developer at PLANT-MY-TREE

PLANT-MY-TREE®-per-order

The application enables Shopify merchants to automatically place tree-planting orders for every incoming order. By integrating ecological contributions directly into the purchase process, the manual effort for tracking and billing reforestation initiatives is eliminated. The system increases transparency for end customers through real-time visualizations of the ecological impact directly in the storefront. The architecture is based on a modular monolith with Spring Boot in the backend and an integrated React app inside the Shopify admin area. The solution uses webhooks to capture order data in an event-driven way and integrates the weclapp ERP system for automated monthly invoicing. An app proxy mechanism provides dynamic statistics such as CO2 compensation and planted trees without any performance loss for the merchant shop.

Tasks:

  • Design of the modular software architecture based on Spring Modulith to ensure high maintainability
  • Development of the event-driven business logic for evaluating Shopify orders via webhooks
  • Implementation of automated invoicing by connecting the weclapp REST API
  • Building the frontend using React Router and Shopify App Bridge for native integration
  • Design of the database model and implementation of the persistence layer with JPA/Hibernate and Prisma
  • Integration of internationalization processes for global use in the frontend and email communication
  • Automation of deployment processes using Docker and GitLab CI/CD

Project skills: Java 25, Spring Boot, Spring Security, Spring Modulith, Hibernate, JPA, REST API, PostgreSQL, Maven, Liquibase, React, TypeScript, React Router, Vite, Node.js, Prisma, Zod, Docker, Docker Compose, GitLab CI/CD, Shopify CLI, Shopify App Bridge, Polaris, weclapp, i18next, Lombok, Vitest

Verified expert

Beshr Alnirabieh

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Data & Business Analyst | Business Intelligence | AI & Automation

Bonn
Beshr Alnirabieh

Last position:

System Administrator – HealthCare IT & Data Infrastructure at Cellitinnen Hospital Association

  • Integration of medical modalities (including ultrasound) into the existing IT infrastructure (DICOM, HL7) – put into operation within the planned timeframe.
  • Administration and optimization of PACS systems for efficient archiving and distribution of radiology image data across multiple locations.
  • Ensuring consistent data quality and seamless interoperability in data exchange between HIS, RIS, and PACS.
  • Close collaboration with medical staff to analyze and digitally optimize clinical workflows.
  • Requirements management and test coordination when implementing clinical requirements in complex IT structures.
Verified expert

Rodion Orlinskiy

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Founder, CTO & Managing Director

Bonn
Rodion Orlinskiy

Last position:

Founder, CTO & Managing Director at MYNR Product Mining GmbH

  • Responsible for the architecture and development of an AI-native SaaS platform for industrial product portfolio management.
  • Designed the modern data platform architecture on Azure for scalable analytics and enterprise data integration.
  • Built enterprise data ingestion and transformation pipelines across complex industrial system landscapes.
  • Developed graph-based representations of product structures and dependencies for analytical reasoning.
  • Designed and implemented an agentic AI framework for AI-supported decision workflows.
  • Built scalable analytical microservices and integrated reporting through modern BI technologies.
  • Coordinated backend, AI, and frontend development across the MYNR platform stack.
Verified expert

Sophia Wagner

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AI Engineer & Technical Consultant

Cologne
Sophia Wagner

Last position:

AI Engineer & Technical Consultant at Freelance

  • Delivered ML pipelines for OCR, semantic search, and computer vision
  • Integrated Azure AI Agents and GPT workflows for automation and QA
  • Deployed cloud-based FastAPI services with scalable architecture
  • Created integration docs and advised on LLM production readiness
Verified expert

Yaroslav Shargorodskiy

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Senior Low-Code Consultant

Cologne
Yaroslav Shargorodskiy

Last position:

Senior Low-Code Consultant at Freelancer

  • Structured analysis and evaluation of business processes

  • Gathering, documenting, and prioritizing requirements

  • Creating business-friendly and technically executable process models

  • Use of Camunda tools

  • Deriving requirements and interfaces from BPMN diagrams

  • Coordination with stakeholders and business units

  • Translating business requirements into technical solution designs

  • Implementing efficient and tailored applications

  • Systematic collection, analysis, and documentation of requirements

  • Prioritizing and validating requirements in close collaboration with stakeholders

  • Alignment between business and development to ensure shared objectives

  • Creating use cases, user stories, and acceptance criteria

  • Continuous requirements and change management throughout the project lifecycle

  • Define project goals and create project plans

  • Delegate tasks and monitor project progress

  • Monitor budgets and inform stakeholders

  • Mendix: Architecture, development, and maintenance of custom applications (Microflows, Domain Model, Security, XPath)

  • Modeling Mendix workflows for process optimization

  • Develop scalable apps with Mendix including REST/SOAP integration with SAP, SQL, Azure & SharePoint

  • UI design for Mendix using Atlas UI, Fluent UI, HTML, CSS, JavaScript

  • Develop web & mobile apps with Mendix using agile methods (Scrum, Kanban)

  • Implement business logic with Mendix Microflows and Nanoflows

  • Performance optimization and architecture improvements for Mendix applications

  • Conduct Mendix training

  • Create technical documentation and best practices for Mendix

  • Coaching and mentoring for low-code development with Mendix

Verified expert

Rainer Langbehn

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Senior IT Consultant, Senior Software Architect, Senior Software Developer, Senior DevOps Engineer

Cologne
Rainer Langbehn

Last position:

Senior IT Consultant, Senior Software Architect, Senior Software Developer, Senior DevOps Engineer at Techniker Krankenkasse

  • Automation of the database major / minor releases for the TKeasy project

  • Concept for database major / minor release automation

  • As-is analysis

  • Evaluation of Redgate Flyway functionality

  • Concept creation

  • Products: Redgate Flyway, GitHub, Quest, Erwin Data Modeller, Oracle, Atlassian Jira, Atlassian Confluence

  • Skills: Docker, Continuous Delivery, Continuous Integration, Redgate Flyway, Major Releases, Minor Releases

Verified expert

Johannes Wagner

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Senior Data Engineer

Köln
Johannes Wagner

Last position:

Senior Data Engineer at Soorce GmbH

  • Analysis of business requirements
  • Integration of different data sources such as ERP systems, production systems, and external data sources
  • Implementation of load processes and processing logic with MSSQL
  • Data modeling and optimization of data models
  • Setting up data quality management incl. data profiling with dynamic programming
  • Support in designing and establishing data governance, especially in the areas of data quality management and data protection
  • Support in developing BI solutions with Tableau to help decision-making processes
Verified expert

Hüseyin Altuntas

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Business Analyst

Köln
Hüseyin Altuntas

Last position:

Business Analyst at Niedersächsisches Ministerium für Inneres, Sport und Digitalisierung

  • Responsibility, also as rollout manager, for the successful transition of a basic OZG platform into the client's standard operations by planning and implementing measures along Service Transition and Service Operation according to ITIL, including workshops in a SAFe environment with more than 40 operational stakeholders
  • Building and maintaining cross-organizational stakeholder relationships by organizing and running various information sessions on technical configurations and user guides (platform and EfA services)
  • Designing and improving various operational and project documents such as the ITIL operations manual, OLA, SLA, service support concept and rollout instructions
  • Modeling project-based processes according to BPMN 2.0, EPK and UML related to OZG services with the goal of integrating them into the operational e-government process landscape (SOA)
  • Coordinating operational stakeholders and KPI reporting to the project management team using agile methods according to SAFe
  • Tech stack / tools: Microsoft 365 (SharePoint, OneNote, Outlook, Teams), Skype for Business, Cisco Webex, ADONIS, MindManager, Jira, Confluence
Verified expert

Stefan Marx

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Installation Portal Server and Content Management Integration

Köln
Stefan Marx

Last position:

Bundesrechtsanwaltskammer

  • Design, planning and execution of complex acceptance tests for a document exchange platform for the German justice authorities.
  • Validation of decrypted and certificate-based message exchange via web platform, mobile app, and Java API.
  • Documentation of test cases, execution steps, and test results.
  • Technologies: Windows 11/10, Ubuntu, iOS, Android, Bash for Windows, Java 17, IntelliJ, Git, Jira, Confluence, Citrix Server, xJustiz standard implementation, specific justice software.

Discover over 15,000 top freelancers

Statistics of experts using SQL

Aggregated from the professional profiles of matched freelancers.

Experience

18 years (Germany: 19 years)

Position duration

3.2 years (Germany: 5.2 years)

Positions per freelancer

12

Top business areas

Information Technology, Business Intelligence, Product Development

Top industries

Information Technology, Professional Services, Banking and Finance

Certification focus areas

Information Technology, Project Management, Product Development

Bachelor's degree or higher

96% (Germany: 89%)

Master's degree or higher

70% (Germany: 59%)

Doctorate

11% (Germany: 9%)

Certifications per freelancer

3

Most common languages

German, English, French

Speak two or more languages

98% (Germany: 97%)

Based on our profile pool as of 30 Aug 2026.

Daily rate distribution

0 10 20 30 40
<€400 €400-​800 €800-​1200 €1200-​1600 €1600+

The chart shows how the daily rates of freelancers in this technology in Cologne 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 Cologne using SQL

Rates are based on recent contracts and do not include FRATCH margin.

800
600
400
200
Rate comparison chart
Daily rate avg. 778 €
Germany avg. 756 €

The average daily rate is the mean of all daily rates from recent contracts of comparable freelancers on our platform.

800
600
400
200
Rate comparison chart
Median rate 760 €
Germany median 760 €

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 30 Aug 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.

About the technology

Core use

SQL is the language behind relational data work. Companies use it to query tables, join records, and keep reports, apps, and dashboards aligned with the same source of truth. It is common in PostgreSQL, MySQL, Microsoft SQL Server, Oracle Database, and SQLite.

What experts do

  • Write queries for reporting, APIs, and internal tools
  • Design schemas, keys, views, and stored procedures
  • Improve performance with indexes and query tuning
  • Support data migrations, cleanup, and validation

Strong SQL specialists think about data shape, not just syntax. They know how a query behaves on real workloads and how to keep results correct as systems grow.

Tools and ecosystem

A strong SQL professional usually works across database platforms and surrounding tools such as dbt, Liquibase, Flyway, and BI tools like Power BI or Tableau. They also know how to read execution plans, handle transactions, and work with permissions and roles.

When to bring one in

Companies bring in SQL expertise when reports are slow, data is inconsistent, or a schema change needs care. It also helps during migrations, warehouse work, audit fixes, and when Cologne teams need support that fits with English-speaking stakeholders and local business users.

Good project fit

  • Database design for new products or modules
  • Query refactoring and performance cleanup
  • ETL and warehouse logic for analytics
  • Data quality checks and migration support

In Cologne, SQL work often touches commerce, logistics, media, and finance systems. Freelance support works well when the task has clear ownership, sensitive data needs disciplined handling, or the team needs short-term help without changing the core setup.

What strong specialists deliver

The best SQL experts write code that is easy to read, test, and maintain. They ask about indexes, locking, isolation levels, and edge cases before they change anything. They leave behind queries and structures that other specialists can safely build on.

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Frequently asked questions

Before you brief your next project: the most common questions about SQL.

SQL is used to store, read, change, and analyze data in relational databases. Companies rely on it for product data, customer records, reporting, finance checks, and application back ends. It is also the basis for many BI and warehouse workflows.

SQL is the query language, while PostgreSQL and MySQL are database systems that implement it. The language is shared, but each database has its own functions, data types, and performance behavior. A good specialist knows the standard and the platform-specific details.

Bring in a SQL specialist when the team is blocked on a tricky query, a migration, or a performance issue. It is also useful when you need clean schema work or reporting logic without adding a permanent hire. Freelance support fits well for focused, well-scoped data tasks.

A strong SQL expert usually understands data modeling, indexing, transaction handling, and debugging query plans. Depending on the project, Python, ETL tools, BI platforms, and cloud data warehouses can also matter. For application work, knowledge of the surrounding backend stack helps a lot.

The right level depends on the task, but SQL work often needs more than basic query writing. Simple reporting fixes may only need a specialist with solid hands-on practice, while schema redesign or tuning on busy systems calls for deeper platform knowledge. The key is proven work on similar data problems.

Most SQL work can be done remotely because queries, schemas, and plans are digital artifacts. On-site time can help when a project needs close coordination with local teams, stakeholders, or restricted systems. Many companies use a hybrid setup for that reason.

A strong SQL specialist explains why a query is written a certain way and what trade-offs it makes. Look for clear logic, careful handling of nulls and duplicates, and signs that they think about indexes, locking, and maintainability. Good work should be easy for another specialist to review and extend.

SQL is built for structured, relational data with clear relationships and strong query support. NoSQL systems are better suited to certain flexible or high-scale patterns, but they usually require different modeling habits. Many real systems use both, so the best specialist knows where each fits.

The average hourly rate of freelancers in Cologne, Germany who have used SQL in their recent projects is 97 €, which corresponds to a daily rate of about 778 € based on an 8-hour working day.

Of the freelancers in Cologne, Germany who have used SQL in their recent projects, 96% hold at least a Bachelor's degree, 70% hold at least a Master's degree, and 11% hold a doctorate.

On average, freelancers in Cologne, Germany who have used SQL in their recent projects have 18 years of professional experience, with a single engagement typically lasting around 3.2 years.

The most common languages among freelancers in Cologne, Germany who have used SQL in their recent projects are German (98%), English (98%), and French (23%).

The most common industries among freelancers in Cologne, Germany who have used SQL in their recent projects are Information Technology (85%), Professional Services (46%), and Banking and Finance (43%).

The most common business areas among freelancers in Cologne, Germany who have used SQL in their recent projects are Information Technology (93%), Business Intelligence (69%), and Product Development (69%).

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.

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