SPI_gettypeid
Name
SPI_gettypeid -- return the data type 
OID of the specified column
Synopsis
Oid SPI_gettypeid(TupleDesc rowdesc, int colnumber)
Description
SPI_gettypeid returns the OID of the data type of the specified column. 
Arguments
- TupleDesc rowdesc
-  input row description  
- int colnumber
-  column number (count starts at 1)  
Return Value
 The OID of the data type of the specified column or InvalidOid on error. On error, SPI_result is set to SPI_ERROR_NOATTRIBUTE.