1. A computer-implemented method, comprising: receiving natural language input at a computing device; processing the natural language input to generate an output, by: processing the natural language input in a first conditional random field to obtain a first stage output from the first conditional random field, the processing in the first conditional random field comprises: extracting at least a first entity and a second entity from the natural language input, wherein the first entity and the second entity appear separately in a natural language query expressed with the received natural language input, and at least one of the first entity and the second entity identifies a column name of a database table; and labeling the first entity as a database column value for the database table, and labeling the second entity as a database column name for the database table, the first stage output comprising a database column value label associated with the first entity and a database column name label associated with the second entity; and after processing the natural language input in the first conditional random field, processing the natural language input and the first stage output in a second conditional random field to obtain a second stage output from the second conditional random field, the processing in the second conditional random field comprising identifying at least one relationship between the first entity and the second entity in the first stage output, the second stage output comprising information that represents the at least one relationship, wherein the output comprises the first stage output and the second stage output; and forming a search query based at least in part on the output, wherein forming the query comprises determining a query type, wherein the query type is at least one of a range query, a logical query, a join query, or an aggregate query, and wherein the query is based at least in part on the query type.