In an example, columns in a data table may be categorized according to a data type based upon an analysis of data elements contained in each column with a grammar file. The data type of a column be may be categorized as one of a general data type and a specific data type. In addition, the grammar file may be expanded by at least one of adding a data element to the grammar file in response to a column being categorized as a specific data type and inserting a new data type to the grammar file in response to a column being categorized as a general data type.