Passing structured type parameters to external routines

When you pass structured type parameters to an external routine, you should pass a parameter for each attribute. You must pass a null indicator for each parameter and a null indicator for the structured type itself.

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The following example accepts the structured type Address_t and returns a base type:

   CREATE FUNCTION stream_to_client (Address_t)
      RETURNS VARCHAR(150) ...

The external routine must accept the null indicator for the instance of the Address_t type (address_ind) and one null indicator for each of the attributes of the Address_t type. There is also a null indicator for the VARCHAR output parameter. The following code represents the C language function headers for the functions that implement the UDFs:

   void SQL_API_FN stream_to_client(
   /* decomposed address */
      SQLUDF_VARCHAR *street,
      SQLUDF_CHAR *number,
      SQLUDF_VARCHAR *city,
      SQLUDF_VARCHAR *state,
   /* VARCHAR output */
      SQLUDF_VARCHAR *output,
   /* null indicators for type attributes */
      SQLUDF_NULLIND *street_ind,
      SQLUDF_NULLIND *number_ind,
      SQLUDF_NULLIND *city_ind,
      SQLUDF_NULLIND *state_ind,
   /* null indicator for instance of the type */
      SQLUDF_NULLIND *address_ind,
   /* null indicator for the VARCHAR output */
      SQLUDF_NULLIND *out_ind,
      SQLUDF_TRAIL_ARGS)

Suppose that the routine accepts two different structured type parameters, st1 and st2, and returns another structured type of st3:

   CREATE FUNCTION myudf (int, st1, st2)
      RETURNS st3

Table 1. Attributes of myudf parameters
ST1	ST2	ST3
st1_att1 VARCHAR	st2_att1 VARCHAR	st3_att1 INTEGER
st2_att2 INTEGER	st2_att2 CHAR	st3_att2 CLOB
	st2_att3 INTEGER

The following code represents the C language headers for routines that implement the UDFs. The arguments include variables and null indicators for the attributes of the decomposed structured type and a null indicator for each instance of a structured type, as follows:

  void SQL_API_FN myudf(
      SQLUDF_INTEGER *INT,
   /* Decomposed st1 input */
      SQLUDF_VARCHAR *st1_att1,
      SQLUDF_INTEGER  *st1_att2,
   /* Decomposed st2 input */
      SQLUDF_VARCHAR *st2_att1,
      SQLUDF_CHAR   *st2_att2,
      SQLUDF_INTEGER *st2_att3, 
   /* Decomposed st3 output */
      SQLUDF_VARCHAR *st3_att1out,
      SQLUDF_CLOB   *st3_att2out, 
   /* Null indicator of integer */
      SQLUDF_NULLIND *INT_ind,
   /* Null indicators of st1 attributes and type */
      SQLUDF_NULLIND *st1_att1_ind,
      SQLUDF_NULLIND *st1_att2_ind,
      SQLUDF_NULLIND *st1_ind,
   /* Null indicators of st2 attributes and type */
      SQLUDF_NULLIND *st2_att1_ind,
      SQLUDF_NULLIND *st2_att2_ind,
      SQLUDF_NULLIND *st2_att3_ind,
      SQLUDF_NULLIND *st2_ind,
   /* Null indicators of st3_out attributes and type */
      SQLUDF_NULLIND *st3_att1_ind,
      SQLUDF_NULLIND *st3_att2_ind,
      SQLUDF_NULLIND *st3_ind,
   /* trailing arguments */
      SQLUDF_TRAIL_ARGS
   )