The sysextcols system catalog table contains a row that describes each of the internal columns in external table tabid of format type (fmttype) FIXED.

The sysextcols table has the following columns.
Column Type Explanation
tabid INTEGER Unique identifying code of a table
colno SMALLINT Code identifying the column
exttype SMALLINT Code identifying an external column type
extstart SMALLINT Starting position of column in the external data file
extlength SMALLINT External column length (in bytes)
nullstr CHAR(256) Represents NULL in external data
decprec SMALLINT Precision for external decimals
extstype VARCHAR(128,0) External type name

No entries are stored in sysextcols for DELIMITED or HCL OneDB™ format external files.

You can use the DBSCHEMA utility to write out the description of the external tables. To query these system catalog tables about an external table, use the tabid as stored in systables with tabtype = ‘E'.

An index on the tabid column allows duplicate values.