Provided by: tcl8.6-tdbc_1.0.6-1_amd64 
NAME
tdbc::resultset - TDBC result set object
SYNOPSIS
package require tdbc 1.0
package require tdbc::driver version
tdbc::driver::connection create db ?-option value...?
set stmt [db prepare sql-code]
set resultset [$stmt execute ?args...?]
$resultset columns
$resultset rowcount
$resultset nextrow ?-as lists|dicts? ?--? varname
$resultset nextlist varname
$resultset nextdict varname
$resultset nextresults
$resultset allrows ?-as lists|dicts? ?-columnsvariable name? ?--?
$resultset foreach ?-as lists|dicts? ?-columnsvariable name? ?--? varname script
$resultset close
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DESCRIPTION
Every database driver for TDBC (Tcl DataBase Connectivity) implements a result set object
that represents a the results returned from executing SQL statement in a database.
Instances of this object are created by executing the execute object command on a
statement object.
The columns object command returns a list of the names of the columns in the result set.
The columns will appear in the same order as they appeared in the SQL statement that
performed the database query. If the SQL statement does not return a set of columns (for
instance, if it is an INSERT, UPDATE, or DELETE statement), the columns command will
return an empty list.
The rowcount object command returns the number of rows in the database that were affected
by the execution of an INSERT, UPDATE or DELETE statement. For a SELECT statement, the
row count is unspecified.
The nextlist object command sets the variable given by varname in the caller's scope to
the next row of the results, expressed as a list of column values. NULL values are
replaced by empty strings. The columns of the result row appear in the same order in which
they appeared on the SELECT statement. The return of nextlist is 1 if the operation
succeeded, and 0 if the end of the result set was reached.
The nextdict object command sets the variable given by varname in the caller's scope to
the next row of the results, expressed as a dictionary. The dictionary's keys are column
names, and the values are the values of those columns in the row. If a column's value in
the row is NULL, its key is omitted from the dictionary. The keys appear in the
dictionary in the same order in which the columns appeared on the SELECT statement. The
return of nextdict is 1 if the operation succeeded, and 0 if the end of the result set
was reached.
The nextrow object command is precisely equivalent to the nextdict or nextlist object
command, depending on whether -as dicts (the default) or -as lists is specified.
Some databases support the idea of a single statement that returns multiple sets of
results. The nextresults object command is executed, typically after the nextlist of
nextdict object command has returned 0, to advance to the next result set. It returns 1 if
there is another result set to process, and 0 if the result set just processed was the
last. After calling nextresults and getting the return value of 1, the caller may once
again call columns to get the column descriptions of the next result set, and then return
to calling nextdict or nextlist to process the rows of the next result set. It is an
error to call columns, nextdict, nextlist or nextrow after nextresults has returned 0.
The allrows object command sets the variable designated by the -columnsvariable option (if
present) to the result of the columns object command. It then executes the nextrow object
command repeatedly until the end of the result set is reached. If nextresults returns a
nonzero value, it executes the above two steps (columns followed by iterated nextrow
calls) as long as further results are available. The rows returned by nextrow are
assembled into a Tcl list and become the return value of the allrows command; the last
value returned from columns is what the application will see in -columnsvariable.
The foreach object command sets the variable designated by the -columnsvariable option (if
present) to the result of the columns object command. It then executes the nextrow object
command repeatedly until the end of the result set is reached, storing the successive rows
in the variable designated by varName. For each row, it executes the given script. If the
script terminates with an error, the error is reported by the foreach command, and
iteration stops. If the script performs a break operation, the iteration terminates
prematurely. If the script performs a continue operation, the iteration recommences with
the next row. If the script performs a return, results are the same as if a script
outside the control of foreach had returned. Any other unusual return code terminates the
iteration and is reported from the foreach.
Once nextrow returns 0, the foreach object command tries to advance to the next result set
using nextresults. If nextresults returns 1, the above steps (columns and nextrow, with
script invocation) are repeated as long as more result sets remain. The script will always
see the correct description of the columns of the current result set in the variable
designated byt -columnsvariable. At the end of the call, the variable designated by
-columnsvariable will have the description of the columns of the last result set.
The close object command deletes the result set and frees any associated system resources.
SEE ALSO
encoding(3tcl), tdbc(3tcl), tdbc::connection(3tcl), tdbc::statement(3tcl),
tdbc::tokenize(3tcl)
KEYWORDS
TDBC, SQL, database, connectivity, connection, resultset, statement, bound variable,
stored procedure, call
COPYRIGHT
Copyright (c) 2008 by Kevin B. Kenny.