It is a long-term desire to minimize the communication gap between the computer and a human. In natural language processing, the work has been done in different directions (such as text, speech). In this book, the NLIDB for English/Urdu and similar languages has been covered. The book presents a column-value or attribute-value mapping algorithm that optimizes the transformation of a natural language query to SQL, hence improves the word to tag mapping. The proposed algorithm is capable to solve simple queries with multiple simple joins. It refuses intractable queries and answers correctly, if the query is semantically tractable. The algorithm has been implemented in Visual C#.NET and tested on a database containing students and employees information. The proposed algorithm correctly maps most of the natural language queries to SQL.