NLI4DB: A Systematic Review of Natural Language Interfaces for Databases

As the demand for querying databases in all areas of life continues to grow, researchers have devoted significant attention to the natural language interface for databases (NLIDB). This paper presents a comprehensive survey of recently proposed NLIDBs. We begin with a brief introduction to natural language processing techniques, executable database languages and the intermediate representation between natural language and executable language, and then provide an overview of the translation process from natural language to executable database language. The translation process is divided into three stages: (i) natural language preprocessing, (ii) natural language understanding, and (iii) natural language translation. Traditional and data-driven methods are utilized in the preprocessing stage. Traditional approaches rely on predefined rules and grammars, and involve techniques such as regular expressions, dependency parsing and named entity recognition. Data-driven approaches depend on large-scale data and machine learning models, using techniques including word embedding and pattern linking. Natural language understanding methods are classified into three categories: (i) rule-based, (ii) machine learning-based, and (iii) hybrid. We then describe a general construction process for executable languages over relational and spatio-temporal databases. Subsequently, common benchmarks and evaluation metrics for transforming natural language into executable language are presented, and methods for generating new benchmarks are explored. Finally, we summarize the classification, development, and enhancement of NLIDB systems, and discuss deep language understanding and database interaction techniques related to NLIDB, including (i) using LLM for Text2SQL tasks, (ii) generating natural language interpretations from SQL, and (iii) transforming speech queries into SQL.