Once features have been inserted into a database, you may need to update the data as values change. Updating a feature involves the following steps:

1. Identify which features to update by formulating a query. The query can involve an attribute, a spatial constraint, or both. The SE_stream_update_table function is used to define the query.
2. Set which values to update by setting or binding individual values. Values are set by data type (SE_stream_set_string, SE_stream_set_integer, etc.) or bound to memory locations with SE_stream_bind_input_column.
3. Execute the query with SE_stream_execute.

You can execute updates against a single feature or a collection of features. For example, individual parcels can be identified by using a unique identifier in the query:

strcpy (where, "Parcel_ID = 12345");

/*When executed, a single parcel with Parcel_ID = 12345 will have the
* specified columns updated. You can update groups of features by formulating
* a query that selects multiple features:*/

num_cols = 3;

attrs = malloc (num_cols * sizeof (CHAR *));
attrs[0] = "area";
attrs[1] = "population";
attrs[2] = "boundary";

/* Formulate the where clause to update the correct city */
strcpy (where, "city_name = 'Aylmer'");

/* Initialize the stream with the update operation */
rc = SE_stream_update_table (stream, "cities", num_cols, (const char **)attrs, where);

/* See Error handling section for check_error function code. */
check_error(NULL, Stream, rc, "SE_stream_update_table");

/* Bind the address of our input variables and indicators */
rc = SE_stream_bind_input_column (stream, 1, &area, &area_indicator);
check_error(NULL, Stream, rc, "SE_stream_bind_input_column");

rc = SE_stream_bind_input_column (stream, 2, &population, &pop_indicator);
check_error(NULL, Stream, rc, "SE_stream_bind_input_column");

rc = SE_stream_bind_input_column (stream, 3, shape, &shape_indicator);
check_error(NULL, Stream, rc, "SE_stream_bind_input_column");

/* Set the indicators for non NULL input data */
area_indicator = SE_IS_NOT_NULL_VALUE; pop_indicator = SE_IS_NOT_NULL_VALUE;
shape_indicator = SE_IS_NOT_NULL_VALUE;

/* Execute the update statement */
rc = SE_stream_execute (stream);
check_error(NULL, Stream, rc, "SE_stream_execute");

free (attrs);