Using &NDB Verbs › Put It All Together—Unload or Reload an NDB › Build a Format for Reading Data

Build a Format for Reading Data

To efficiently read the data, you predefine a format that contains all fields. However, you rename each field to Fnnnn on retrieval. This prevents any clashes with the control fields, if, for example, the database contains a field called I. You also ask that null fields not be returned, to save processing overheads.

You then loop through the vartable built previously, to build a format using START/DATA/END:

&I = 1

&NDBFMT &DBNAME DEFINE FORMAT=UFMT START
&NDBFMT &DBNAME DATA FIELDS
&DOWHILE &I LE &FNUM
   &VARTABLE GET ID=FTAB KEY=I FIELDS=DATA VARS=FNAME
   &NDBFMT &DBNAME DATA (F&I = &FNAME NULLFIELD=NORETURN)
   &I = &I + 1
   &LOOPCTL 1000
&DOEND
&NDBFMT &DBNAME END