Append a new, empty record at the end of a specified E-kernel segment.
Variable I/O Description -------- --- -------------------------------------------------- handle I File handle. segno I Segment number. recno O Number of appended record.
handle is a file handle of an EK open for write access. segno is the number of the segment to which the record is to be added. EK segment numbers range from zero to N-1, where N is the number of segments in the kernel.
recno is the number of the record appended by this routine. recno is used to identify the record when writing column entries to it. EK record numbers range from 0 to N-1, where N is the number of records in the segment containing the record.
This routine operates by side effects: It appends a new, empty record structure to an EK segment. The ordinal position of the new record is one greater than the previous number of records in in the segment. After a new record has been appended to a segment by this routine, the record must be populated with data using the ekace*_c routines. EKs are valid only when all of their column entries are initialized. To insert a record into a segment at a specified ordinal position, use the routine ekappr_c. This routine cannot be used with the "fast write" suite of routines. See the EK Required Reading for a discussion of the fast writers.
1) Append a record to a specified segment. Suppose we have an E-kernel named order_db.ek which contains records of orders for data products. The E-kernel has a table called DATAORDERS that consists of the set of columns listed below: DATAORDERS Column Name Data Type ----------- --------- ORDER_ID INTEGER CUSTOMER_ID INTEGER LAST_NAME CHARACTER*(*) FIRST_NAME CHARACTER*(*) ORDER_DATE TIME COST DOUBLE PRECISION The order database also has a table of items that have been ordered. The columns of this table are shown below: DATAITEMS Column Name Data Type ----------- --------- ITEM_ID INTEGER ORDER_ID INTEGER ITEM_NAME CHARACTER*(*) DESCRIPTION CHARACTER*(*) PRICE DOUBLE PRECISION We'll suppose that the file order_db.ek contains two segments, the first containing the DATAORDERS table and the second containing the DATAITEMS table. If we wanted to insert a new record into the DATAORDERS table in position 0, we'd make the following calls: #include "SpiceUsr.h" . . . /. Open the database for write access. This call is made when the file already exists. See ekopn_c for an example of creating a new file. ./ ekopw_c ( "order_db.ek", &handle ); /. Append a new, empty record to the DATAORDERS table. Recall that the DATAORDERS table is in segment number 0. The call will return the number of the new, empty record. ./ ekappr_c ( handle, 0, &recno ); /. At this point, the new record is empty. A valid EK cannot contain empty records. We fill in the data here. Data items are filled in one column at a time. The order in which the columns are filled in is not important. We use the ekace*_c (add column entry) routines to fill in column entries. We'll assume that no entries are null. All entries are scalar, so the entry size is 1. ./ isnull = SPICEFALSE; size = 1; /. The following variables will contain the data for the new record. ./ ordid = 10011; custid = 531; lname = "scientist"; fname = "joe"; odate = "1995-sep-20"; cost = 5000.; /. Note that the names of the routines called correspond to the data types of the columns: the last letter of the routine name is C, I, or D, depending on the data type. Time values are converted to ET for storage. ./ ekacei_c ( handle, segno, recno, "order_id", size, ordid, isnull ); ekacei_c ( handle, segno, recno, "customer_id", size, custid, isnull ); ekacec_c ( handle, segno, recno, "last_name", size, vallen, lname, isnull ); ekacec_c ( handle, segno, recno, "first_name", size, vallen, fname, isnull ); utc2et_c ( odate, &et ); ekaced_c ( handle, segno, recno, "order_date", size, et, isnull ); ekaced_c ( handle, segno, recno, "cost", size, cost, isnull ); /. Close the file to make the update permanent. ./ ekcls_c ( handle );
1) If handle is invalid, the error will be diagnosed by routines called by this routine. The file will not be modified. 2) If segno is out of range, the error SPICE(INVALIDINDEX) will be signalled. The file will not be modified. 3) If an I/O error occurs while reading or writing the indicated file, the error will be diagnosed by routines called by this routine. The file may be corrupted.
See the EK Required Reading for a discussion of the EK file format.
N.J. Bachman (JPL)
-CSPICE Version 1.0.0, 09-JAN-2002 (NJB)
append record to EK segment