6. A non-transitory computer storage medium encoded with computer program instructions that when executed by one or more computers cause the one or more computers to perform operations comprising: receiving a first executable statement, the first executable statement referencing a second set of fields in a dataset, the first executable statement having instructions to cause the query processor to perform operations on data in the dataset; generating a second executable statement based on the first set of fields and the first executable statement, comprising: determining a mapping between the first set of fields and the second set of fields, comprising: identifying a first data type of a first field in the first set of fields, identifying a second data type of a second field in the second set of fields, identifying a conversion command to convert from the first data type to the second data type, and adding the conversion command to the second executable statement, specifying a derived dataset using the corresponding values and the mapping, and generating instructions to cause the query processor to perform the operations on the derived dataset; and sending the second executable statement to the query processor.
7. The non-transitory computer storage medium of claim 6 , further comprising: receiving result data from the query processor associated with the execution of the operations in the second executable statement; determining that the data from the user interface is invalid based on the result data.