SPI_gettype
SPI_gettype — return the data type name of the specified column
Synopsis
char * SPI_gettype(TupleDescrowdesc, intcolnumber)
Description
SPI_gettype returns a copy of the data type name of the specified column. (You can use pfree to release the copy of the name when you don't need it anymore.) 
Arguments
- TupleDesc- rowdesc
- input row description 
- int- colnumber
- column number (count starts at 1) 
Return Value
 The data type name of the specified column, or NULL on error. SPI_result is set to SPI_ERROR_NOATTRIBUTE on error.