<p>The rapid advancements in Deep Neural Networks (DNNs) have revolutionized generative software engineering tasks, including code summarization, program repair, code generation, and code translation. However, the performance of DNN models in these tasks heavily depends on the quality of their training and evaluation datasets. This systematic literature review examines 70 primary studies to comprehensively analyze dataset construction methodologies, prevalent data quality challenges, and solutions proposed to address these challenges. Our findings reveal that dataset construction processes significantly influence quality, with common issues such as noise, redundancy, imbalance, and insufficient granularity undermining model effectiveness. We identify key strategies to mitigate these problems, including data augmentation, automated cleaning techniques, and standardized validation frameworks. Furthermore, we highlight the critical role of dataset diversity and timeliness in improving model generalization. This study provides actionable insights for researchers and practitioners in the era of generative AI, where high-quality datasets are essential for developing reliable language models as software engineering tools. By emphasizing rigorous dataset curation and innovative quality assurance methods, our work bridges the gap between theoretical advancements and practical applications, enabling the creation of robust, generalizable models for real-world code-related tasks. The synthesized recommendations aim to guide future research in optimizing dataset design, fostering reproducibility, and addressing evolving challenges in data-driven software engineering.</p>