1 Version 4.0 -- 5/1/89 dbtabcount
______________________________________________________________________
NAME: dbtabcount
FUNCTION:
Return the number of tables involved in the current SELECT query.
SYNTAX:
int dbtabcount(dbproc)
DBPROCESS *dbproc;
COMMENTS:
o dbtabcount() is one of the DB-Library browse mode routines. It
dbtabcount Version 4.0 -- 5/1/89 2
______________________________________________________________________
is usable only with results from a browse-mode SELECT (i.e., a
SELECT containing the key words FOR BROWSE). See the Introduc-
tion for a detailed discussion of browse mode.
o A SELECT query can generate a set of result rows whose columns
are derived from several database tables. To perform browse-
mode updates of columns in a query's select-list, the applica-
tion must know how many tables were involved in the query,
because each table requires a separate UPDATE statement.
dbtabcount() can provide this information for ad hoc queries.
If the query has been hardcoded into the program, this routine
is obviously unnecessary.
o The count returned by this routine includes any SQL Server
"work tables" used in processing the query. The SQL Server
sometimes creates temporary, internal work tables to process a
query. It deletes these work tables by the time it finishes
processing the statement. Work tables are not updatable and
3 Version 4.0 -- 5/1/89 dbtabcount
______________________________________________________________________
are not available to the application. Therefore, before using
a table number, the application must make sure that it does not
belong to a work table. dbtabname() can be used to determine
whether a particular table number refers to a work table.
o The application can call dbtabcount() any time after
dbresults().
o Example 7 in the DB-Library Reference Supplement contains a
call to dbtabcount().
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.
RETURNS:
dbtabcount Version 4.0 -- 5/1/89 4
______________________________________________________________________
The number of tables, including SQL Server work tables, involved
in the current set of row results.
dbtabcount() will return -1 in case of error.
SEE ALSO:
dbcolbrowse, dbcolsource, dbqual, dbtabbrowse, dbtabname, dbtab-
source, dbtsnewlen, dbtsnewval, dbtsput