Improving Text-to-Sql Conversion for Low-Resource Languages Using Large Language Models

Accurate text-to-SQL conversion remains a challenge, particularly for low-resource languages like Turkish. This study explores the effectiveness of large language models (LLMs) in translating Turkish natural language queries into SQL, introducing a two-stage fine-tuning approach to enhance performance. Three widely used LLMs Llama2, Llama3, and Phi3 are fine-tuned under two different training strategies, direct SQL fine-tuning and sequential fine-tuning, where models are first trained on Turkish instruction data before SQL fine-tuning. A total of six model configurations are evaluated using execution accuracy and logical form accuracy. The results indicate that Phi3 models outperform both Llama-based models and previously reported methods, achieving execution accuracy of up to 99.95% and logical form accuracy of 99.95%, exceeding the best scores in the literature by 5–10%. The study highlights the effectiveness of instruction-based fine-tuning in improving SQL query generation. It provides a detailed comparison of Llama-based and Phi-based models in text-to-SQL tasks, introduces a structured fine-tuning methodology designed for low-resource languages, and presents empirical evidence demonstrating the positive impact of strategic data augmentation on model performance. These findings contribute to the advancement of natural language interfaces for databases, particularly in languages with limited NLP resources. The scripts and models used during the training and testing phases of the study are publicly available at https://github.com/emirozturk/TT2SQL.