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NAME: dbtabsource
FUNCTION:
Return the name and number of the table from which a particular
result column was derived.
SYNTAX:
char *dbtabsource(dbproc, colnum, tabnum)
DBPROCESS *dbproc;
int colnum;
int *tabnum;
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COMMENTS:
o dbtabsource() is one of the DB-Library browse mode routines.
It is usable only with results from a browse-mode SELECT (i.e.,
a SELECT containing the key words FOR BROWSE). See the Intro-
duction for a detailed discussion of browse mode.
o dbtabsource() allows an application to determine which tables
provided the columns in the current set of result rows. This
information is valuable when using dbqual() to construct WHERE
clauses for UPDATE and DELETE statements based on ad hoc
queries. If the query has been hardcoded into the program,
this routine is obviously unnecessary.
o The application can call dbtabsource() any time after
dbresults().
o Example 7 in the DB-Library Reference Supplement contains a
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call to dbtabsource().
PARAMETERS:
dbproc - A pointer to the DBPROCESS structure that provides the
connection for a particular front-end/SQL Server process. It
contains all the information that DB-Library uses to manage
communications and data between the front end and SQL Server.
colnum - The number of the result column of interest. Column
numbers start at 1.
tabnum - A pointer to an integer, which will be filled in with
the table's number. Many DB-Library routines that deal with
browse mode accept either a table name or a table number. If
dbtabsource() returns NULL (see below), *tabnum will be set
to -1.
RETURNS:
A pointer to the name of the table from which this result column
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was derived. A NULL return value can mean a few different things:
o The DBPROCESS is dead or not enabled. This is an error that
will cause an application's error handler to be invoked.
o The column number is out of range.
o The column is the result of an expression, such as
"max(colname)".
SEE ALSO:
dbcolbrowse, dbcolsource, dbqual, dbtabbrowse, dbtabcount, dbtab-
name, dbtsnewlen, dbtsnewval,