As software systems increasingly rely on natural language interfaces, ensuring the reliability of these systems is crucial. One critical component is the ability to accurately translate natural language queries into corresponding SQL queries, a field known as Text-to-SQL. However, the scarcity of high-quality, large-scale, and domain-specific Text-to-SQL datasets hinders the development of reliable and robust models. To tackle these challenges, we propose SelectCraft, a novel automatic generation approach designed to create realistic Text-to-SQL datasets tailored to specific domains. Our method leverages existing databases and their structures to generate complex text-SQL pairs that mirror real-world usage scenarios. As a proof of concept, we have successfully generated a substantial financial Text-to-SQL dataset, denominated as BanQies, encompassing over 1 million samples utilizing our proposed approach. Moreover, we introduce BanQL, a new large language model (LLM) based on StarCoder2, a state-of-the-art code-based LLM, and fine-tuned on our newly created dataset. We evaluate BanQL performance against several state-of-the-art models, demonstrating significant enhancements in accuracy and generalizability, highlighting the advantages of incorporating domain-specific data in Text-to-SQL tasks. We firmly believe that our contributions have the potential to improve the overall reliability of Text-to-SQL software systems.