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Sybtcl(n) Tcl Sybase Extension Sybtcl(n)
NAME
Sybtcl - Sybase SQL Server access commands for Tcl
INTRODUCTION
Sybtcl is a collection of Tcl commands and a Tcl global array that
provides access to a Sybase Server. Each Sybtcl command generally
invokes several Sybase Open Client (a.k.a. DB-Library) library
functions. Programmers using Sybtcl should be familiar with basic
concepts of DB-Library programming.
SYBTCL COMMANDS
sybconnect login-name password ?server? ?appname? ?ifile? ?charset?
Connect to a Sybase server using login-name and password. If
server is specified, then an attempt will be made to login to
the named Sybase server. If server is not specified, then the
environment variable DSQUERY is used to determine a server; if
DSQUERY is not set, sybconnect will try to connect to the Sybase
server named SYBASE. If an appname is specified, then that
value is passed to the server to display during a process list.
If ifile is specified, that file is used to resolve server
addresses; if not specified, the normal $SYBASE/interfaces file
is used. If charset is specified, the charset should reference
a valid character set available on your Sybase installation.
See the $SYBASE/charsets directory for charsets supported on
your installation.
Login-name and password are required parameters. All other
parameters are optional positional parameters. For example, to
specify the ifile parameter, server and appname must also be
specified. Optional parameters may be a null string, in which
case the default value is used.
A handle is returned and should be used for all other Sybtcl
commands using this connection. Multiple connections to the
same or different servers are allowed, up to a maximum of 50
total connections. Sybconnect raises a Tcl error if the
connection is not made for any reason (login or password
incorrect, server not found in the Sybase interfaces file,
network unavailable, etc.).
syberrhandler ?tclproc?
Set a Tcl procedure to be called upon any DB-Lib error. The Tcl
procedure should exist, and take the following arguments to the
procedure:
handle
The Sybtcl handle associated with the error condition.
Handle may be a null string, such as in the case of an
error occurring during sybconnect.
severity
The Sybase severity level of the error.
dberr The Sybase DB-Lib error code.
oserr The operating system error code.
dberrstr
The DB-Lib error string associated with the error code.
oserrstr
The operating system error string associated with the
error.
Example:
proc err_handler {handle severity dberr oserr dberrstr oserrstr} {
puts "error: $handle $severity $dberr $oserr $dberrstr
$oserrstr"
return 1
}
syberrhandler err_handler
The procedure may also return an integer value to indicate an action to
perform:
"0" print an error message and abort the program
immediately.
"1" continue by returning a "FAIL" condition to the currently
executing DB-Lib function.
"2" cancel the operation that caused the error if a result of
a timeout condition. For any other case, this value is
considered as "0", immediate program termination.
"3" continue to wait for one additional time out period if a
result of a timeout condition. For any other case, this
value is considered as "0", immediate program
termination.
If no value is returned, or any other value is return, Sybtcl treats
the return value as "1" (continue).
Syberrhandler called without an argument returns the current error
handler. If called with a null string, the error handler is disabled.
sybmsghandler ?tclproc?
Set a Tcl procedure to be called upon any server message. The
Tcl procedure should exist, and take the following arguments to
the procedure:
handle
The Sybtcl handle associated with the error condition.
msgno The Sybase server message number.
msgstate
The Sybase server message state.
severity
The Sybase severity level of the error.
msgtext
The server message text.
svrname
The name of the server generating the message.
procname
The name of the procedure generating the message, if any.
line The line number of the procedure generating the message,
if any.
Example:
proc msg_handler {handle msgno msgstate severity msgtext svrname
procname line} {
puts "msg: $handle $msgno $msgstate $severity $msgtext
$svrname $procname $line"
}
syberrhandler msg_handler
Sybghandler called without an argument returns the current message
handler. If called with a null string, the message handler is
disabled.
sybuse handle ?dbname?
Return the database name currently in use. If dbname is
specified, then attempt to use the named database. Handle must
be a valid handle previously opened with sybconnect. If dbname
is used successfully, the dbname is returned. Sybuse raises a
Tcl error if the handle specified is not open or the database
name specified could not be used.
sybsql handle sql-command ?-async?
Send the Sybase Transact SQL statements sql-command to the
server. Handle must be a valid handle previously opened with
sybconnect. If the optional argument -async is specified, then
the SQL is sent to the server without waiting for a response and
sybsql will return immediately with the value "PENDING". The
sybpoll command can be used to check the status of the server
results; sybnext must be called to determine if result rows were
generated. If -async is omitted, then sybsql will wait until
the server has responded. Sybsql will return "REG_ROW" if the
SQL statements generated return rows, "NO_MORE_ROWS" if the SQL
commands executed, but no rows were returned in the first or
only set of results. The sybmsg array index retstatus is set
with the return code of a stored procedure, if any; the nextow
index is also set to the value returned by sybsql.
Multiple SQL statements may be specified in sql-command.
Sybnext allows retrieval of return rows generated; Sybretval
allows retrieval of any return values from stored procedures.
See notes regarding stored procedure output variables.
Sybsql performs an implicit sybcancel if any results are still
pending from the last execution of sybsql. Sybsql raises a Tcl
error if the handle specified is not open, or if the SQL
commands are syntactically incorrect.
Table inserts made with sybsql should follow conversion rules in
the Sybase Commands Reference manual (image or binary data is
hexadecimal string preceded with "0x"; datetime should be a
recognizable date, etc. The SQL Server CONVERT function may be
used to force conversions.
sybpoll handle ?timeout? ?-all?
Return a list of Sybtcl handles that have results waiting.
Handle must be a valid handle previously opened with sybconnect.
If the last SQL results are not ready, a null string is
returned. An optional timeout value in milliseconds may be
specified, which is the amount of time the sybpoll will wait
before returning a result. If the timeout value is -1, sybpoll
will wait until results are available before returning. The
default timeout value is 0, which polls and immediately returns.
The option -all may be specified, in which all handles that have
been executed with -async are checked, and a Tcl list of all
handles that have results waiting are returned. When -all is
combined with a timeout of -1, then sybpoll waits until any
async handle has results waiting, and then returns a list of all
handles that have results waiting. If the last SQL statements
executed with handle were not sent as -async with sybsql,
sybpoll returns a null string.
sybevent handle ?script?
Arrange to run a script when server data is available. Handle
must be a valid handle previously opened with sybconnect.
Sybsql must have previously been executed, without or without
-async mode. The event handler script should execute sybnext in
order to process available data. The event handler may be
executed during any phase of result processing including
REG_ROW, compute rows, NO_MORE_ROWS, and NO_MORE_RESULTS.
If ?script? is not specified, the existing event handler script
is returned. If ?script? is a null string, the event handler is
removed. The event handler is also removed at end of all
results for the current SQL statement.
For the event handler to actually run, the Tcl interpreter must
be processing events. Events can be processed on demand by
executing the Tcl update command, or until a variable is set
with the vwait command. Events are also processed while a Tk
(wish) program is waiting on user input.
Sybtcl's callback handler is greedy; it continues to invoke the
sybevent script while data rows are available. To allow other
Tcl events to be processed, set sybmsg(bgevents) to idletasks or
all.
sybnext handle ?commands? ?substitution_character? ?tclvar colnum ...?
Return the next row from the last SQL statements executed with
sybsql as a Tcl list. Handle must be a valid handle previously
opened with sybconnect. Sybnext raises a Tcl error if the
handle specified is not open. A null string is returned if
there are no more rows in the current set of results. The Tcl
list that is returned by sybnext contains the values of the
selected columns in the order specified by select.
If the SQL statements where executed with the -async option of
sybsql, then sybnext will wait until results are available.
Sybpoll may be used to check for results in a non-blocking
manner. Any errors in the SQL statements will cause sybnext to
fail.
The optional commands argument allows sybnext to repeatedly
fetch rows and execute commands for each row. Substitutions are
made on commands before passing it to Tcl_Eval() for each row.
An optional argument consisting of a single character can be
specified for a column number substitution character. If none
is specified, the character '@' will be used to denote the
substitution character. If the substitution character is a null
string, no column substitutions will be performed on the
commands string. Sybnext interprets the substitution character
followed by a number (@n) in commands as a result column
specification. For example, @1, @2, @3 refer to the first,
second, and third columns in the result. @0 refers to the
entire result row, as a Tcl list. Substitution columns may
appear in any order, or more than once in the same command.
Substituted columns are inserted into the commands string as
proper list elements, i.e., one space will be added before and
after the substitution and column values with embedded spaces
are enclosed by {} if needed.
Tcl variables may also be set for commands on each row that is
processed. Tcl variables are specified after the
substitution_character, consisting of matching pairs of Tcl
variable names and a column numbers. Column number may be "0",
in which the Tcl variable is set to the entire result row as a
Tcl list. Column numbers must be less than or equal to the
number of columns in the SQL result set.
Tcl variable column pairs may also be specified as a list
argument.
Sybnext will execute commands until NO_MORE_ROWS. If additional
results are pending, subsequent sybnext commands will retrieve
the next set of results.
A Tcl error is raised if a column substitution number is greater
than the number of columns in the results. Note that Transact-
SQL "compute" statements are considered to be part of the
current select's result set, and thus, a different number of
columns may be returned, causing the sybnext column substitution
to fail when the compute row is returned. If the commands
execute break, sybnext execution is interrupted and returns with
TCL_OK. Remaining rows may be fetched with a subsequent sybnext
command. If the commands execute return or continue, the
remaining commands are skipped and sybnext execution continues
with the next row. Sybnext will raise a Tcl error if the
commands return an error. Commands should be enclosed in "" or
{}.
The sybmsg array index retstatus is set with the return code of
a stored procedure, if one was executed in the last SQL command
to sybsql; the index nextrow is set to one of several values,
depending on the results of sybnext. Refer to the section
"SERVER MESSAGE AND ERROR INFORMATION" for information about how
the nextrow value is set.
When sybmsg array element binaryashex is set to '1', 'yes', or
'true', sybnext performs conversions for image and binary data.
Data is returned as a hexadecimal string, without a leading
"0x". Use the SQL Server function CONVERT to force a specific
conversion.
The sybmsg array index maxtext limits the amount of text or
image data returned for each column returned. The default is
32768 bytes.
The sybmsg array index nullvalue can be set to specify the value
returned when a column is null. The default is "0" for numeric
data, and "" for other datatypes.
sybcols handle
Return the names of the columns from the last sybnext or
sybretval command as a Tcl list. Sybcols returns the column
name used in the SQL select command; a null string for any
column that is an aggregate function (count, sum, avg, min, max)
in a regular row. A compute row column name is returned as
function(column-name). Sybcols may be used after sybretval, in
which the output variable names are returned (see notes).
The sybmsg array index collengths is set to a Tcl list
corresponding to the lengths of the columns; index coltypes is
set to a Tcl list corresponding to the types of the columns.
Sybcols raises a Tcl error if the handle specified is not open.
sybcancel handle
Cancel any pending results from the last sybsql command. Handle
must be a valid handle previously opened with sybconnect.
Sybcancel may be used before sybnext exhausts all results.
Sybcancel raises a Tcl error if the handle specified is not
open.
sybretval handle
Return a Tcl list of the return values from a stored procedure.
Handle must be a valid handle previously opened with sybconnect.
If a stored procedure also returns rows, sybnext must have
previously been called until NO_MORE_ROWS was encountered before
sybretval can access the return values. The sybmsg array index
retstatus contains the return code from the stored procedure.
Sybretval raises a Tcl error if the handle specified is not
open. See notes regarding stored procedure output variables.
sybwritetext handle object colnum [ -variable varname | -file filename
| filename ] ?-nolog?
Write the contents of a variable or file to a TEXT or IMAGE
column. Handle must be a valid handle previously opened with
sybconnect. Object is the table and column name in the format
table.column. Colnum is the relative position of the column
from the last select. varname is the name of a Tcl variable
containing data, or filename is the name of the file that
contains the text or image data to write into the column. Text
and image writes are logged by default, -nolog may be specified
to disable logging (the database must have previously been set
with a no log option.) If neither -variable or -file is
specified, the argument is interpreted as a filename.
Sybwritetext can only be used in a specific sequence with other
sybsql commands. Refer to the Sybase DB-Library documentation
for dbwritetext() and the DB-Library Reference Supplement
discussion on text/image handling.
For example (assume $hand is an open handle, using the "pubs"
database):
sybsql $hand "insert into au_pix (au_id) values
('111-22-3333')"
sybsql $hand "update au_pix set pic = null where au_id =
'111-22-3333'"
sybsql $hand "select pic from au_pix where au_id =
'111-22-3333'"
sybwritetext $hand au_pix.pic 1 image.file -nolog
An update to an existing text or image column can be made using
the last two commands from the above example. Sybwritetext
returns a integer number upon successful completion of the
number of bytes written to the text/image column.
Sybwritetext raises a Tcl error for a variety of reasons:
filename could not be opened or a failure in internal DB-Library
routines. Common failures are specifying -nolog when the
database does not support nolog; unable to access a valid text
pointer due to invalid object or colnum; sybwritetext used out
of sequence. Consult sybmsg(msgtext) or sybmsg(dberrstr) for
information after a failure.
sybreadtext handle [ -variable varname | -file filename | filename ]
Read the contents of a TEXT or IMAGE column and write results
into a variable or a file. Handle must be a valid handle
previously opened with sybconnect. varname is the name of a Tcl
variable, or Filename is the name of a file in which to write
the text or image data. Sybreadtext can only be used after the
successful select of a single text or image column. If neither
-variable or -file is specified, the argument is interpreted as
a filename. For example (assume $hand is an open handle, using
the "pubs" database):
sybsql $hand "select copy from blurbs where au_id =
'486-29-1786'"
sybreadtext $hand blurb.txt
Sybreadtext returns a decimal number upon successful completion
of the number of bytes read from the text/image column.
Sybreadtext returns "0" if the last select returned more than
one column or no row was returned.
The sybmsg array index maxtext limits the amount of text or
image data that can be written to a file by sybreadtext. The
default is 32768 bytes.
Sybreadtext raises a Tcl error for a variety of reasons:
filename could not be opened, sybreadtext used out of sequence,
etc.
sybclose handle
Closes the server connection associated with handle. Handle
must be a valid handle previously opened with sybconnect.
Sybclose returns a null string. Sybclose raises a Tcl error if
the handle specified is not open.
SERVER MESSAGE AND ERROR INFORMATION
Sybtcl creates and maintains a Tcl global array to provide feedback of
Sybase server messages, named sybmsg. Sybmsg is also used to
communicate with the sybtcl interface routines to specify null return
values and text/image limits. In all cases except for nullvalue,
fixedchar, floatprec, dateformat, bgevents, bgpollinterval and maxtext,
each element is reset to null upon invocation of any sybtcl command,
and any element affected by the command is set. The sybmsg array is
shared among all open sybtcl handles. Sybmsg should be defined with
the global statement in any Tcl procedure needing access to sybmsg.
Sybmsg elements:
version
is set to the version of Sybtcl.
nullvalue
can be set by the programmer to indicate the string value
returned for any null result. Setting sybmsg(nullvalue) to
"default" will return "0" for numeric null data types (integer,
float, and money) and a null string for all other data types.
Nullvalue is initially set to "default".
fixedchar
can be set by the programmer to indicate that character
datatypes returned by sybnext should not have trailing spaces
trimmed from the value. Setting sybmsg(fixedchar) to "1",
"true", or "yes" will ensure that all trailing spaces are
returned. The default value ("") will cause trailing spaces to
be trimmed.
binaryashex
can be set by the programmer to indicate that binary data types
(binary, image) should be converted to hexstrings. Setting
sybmsg(binaryashex) to "1", "true", or "yes" will convert
binary types to hex strings. The default value ("") will cause
binary data to be stored bit-for-bit.
dateformat
can be set by the programmer to indicate formatting for date
data types. The dateformat string can contain substitution
values or literals. Substitutions are made from the list below;
other literals are copied verbatim. The default value is null,
which will format dates a default format.
YYYY
four digit year, 1900-
YY
two digit year, 00-99
MM
two digit month, 1-12
MONTH
name of month, January-December
MON
month abbreviation, Jan-Dec
DD
two digit day, 1-31
hh
two digit hour, 0-23
mm
two digit minute, 0-59
ss
two digit second, 0-59
ms
three digit millisecond, 0-999
dy
three digit day of year, 0-365
dw
one digit day of week, 1-7 (Mon-Sun)
bgevents
can be set by the programmer to allow or disallow the processing
of Tcl events while Sybtcl is waiting for server response.
Events are processed during Sybtcl commands that may wait on
server responses: sybsql (without -async option), sybnext (with
commands option), sybwritetest, and sybreadtext. The default
value is "idletasks". Possible values are:
idletasks
Process only events that have been deferred, such as
display updates. Similar to the Tcl update idletasks
command.
all
Process all events. Similar to the Tcl update command.
none
Do not process events during Sybtcl commands.
bgpollinterval
can be set by the programmer to specify the polling interval in
milliseconds while processing background events. The value
specified must be an integer between 1 and 1000. The default
bgpollinterval value is 200. Smaller values causes the polling
loop to execute more frequently, which may cause higher CPU
usage.
maxtext
can be set by the programmer to limit the amount of text or
image data returned by sybnext and sybreadtext. The default is
32768 bytes. The maximum is 2147483647 bytes. Any value less
than or equal to zero is ignored. Any change to maxtext becomes
effective on the next call to sybsql. See notes on maxtext
usage with sybnext.
handle
indicates the handle of the last sybtcl command. Handle is set
on every sybtcl command (except where an invalid handle is
used.)
isnull
is a list of binary elements corresponding to each column
element returned by sybnext. Each element is set to "1" if the
value is null, "0" if the value is not null.
nextrow
indicates the results of the last SQL command and subsequent
next row processing. Nextrow is set by sybsql and sybnext.
Possible values are:
REG_ROW
at least one row is available after execution of sybsql,
or the results of sybnext returned a row as a Tcl list.
n
an integer number, which indicates that last row
retrieved by sybnext returned a compute row. The value
is the computeid, which is the relative compute statement
in the last SQL command executed with sybsql.
NO_MORE_ROWS
indicates that sybsql executed successfully but no rows
are available, or the results of sybnext did not return a
row. Sybnext will return a null string. Return values
from a stored procedure, if any, are available at this
time. If more results are expected, a subsequent
execution of sybnext will return the first row, if any,
from the next set of results.
PENDING
indicates the last execution of sybsql was made with the
"-async" flag. Sybpoll may be used to check the status
of results. Sybnext will block until results are
available. When sybsql is executed with -async, any
errors will not be available until the first execution of
sybnext.
FAIL
indicates that a server error has occurred. Appropriate
error codes and messages are set in the sybmsg indices
dberr and dberrstr. Sybnext will return a null string.
If more results are expected, a subsequent execution of
sybnext will return the first row, if any, from the next
set of results.
NO_MORE_RESULTS
indicates that the final set of results from the last
execution of sybsql have been processed by sybnext.
retstatus
indicates the return code after a stored procedure has executed.
Retstatus is set by sybsql or sybnext, whenever a the results of
a stored procedure are available.
collengths
is a Tcl list of the lengths of the columns returned by sybcols.
Numeric columns (Sybase datatypes int, float, etc.) are given by
the internal data lengths (e.g., int has a length of 4),
character columns lengths are the maximum of any row returned.
Collengths is only set by sybcols.
coltypes
is a Tcl list of the types of the columns returned by sybcols.
Coltypes is only set by sybcols. Possible types returned are:
char, text, binary, image, tinyint, smallint, int, float, real,
numeric, decimal, bit, money, smallmoney, datetime,
smalldatetime. Varchar and varbinary data types are reported as
char and binary.
msgno
indicates the message number from a Sybase Server message. Can
be set by any sybtcl command. Refer to Sybase documentation for
interpretation. Since each sybtcl command may invoke several
DB-Lib routines, there is a possibility that several messages
may be received from the server. Sybtcl will concatenate all
server message numbers received during one sybtcl command,
separating individual numbers by newlines.
msgtext
the message text associated with msgno. Since each sybtcl
command may invoke several DB-Lib routines, there is a
possibility that several messages may be received from the
server. Sybtcl will concatenate all server messages received
during one sybtcl command, separating individual messages by
newlines. Output from Transact-SQL PRINT statements are
collected in msgtext.
severity
indicates the severity level from a Sybase Server message or DB-
Library routine. Can be set by any sybtcl command. Refer to
Sybase documentation for interpretation.
svrname
indicates the name of the Sybase Server that generated a
message. Can be set by any sybtcl command.
procname
indicates the name of the stored procedure that generated a
message. Only set when a stored procedure was executed. Set by
sybsql.
line
indicates the line number of the SQL command or stored procedure
that generated a message. Set by sybsql.
dberr
indicates the error number generated by a DB-Library routine.
Can be set by any sybtcl command. Refer to Sybase documentation
for interpretation.
dberrstr
the error text associated with dberr.
oserr
indicates an operating system specific error number associated
with a DB-Library error. Can be set by any sybtcl command.
oserrstr
the error text associated with oserr.
dblibinfo
is set to options that were in effect with Sybtcl was compiled.
Possible values are: "system10" if linked with Sybase System 10
DB-Libs or higher, "ctcompt" if compiled with the CT-Lib
compatibility library.
NOTES
Tcl errors can also be raised by any sybtcl command if a command's
internal calls to DB-Library routines fail. Sybtcl will return the
name of the DB-Lib routine that caused an error.
When executing a stored procedure with sybsql, be sure to include in
the SQL commands a "DECLARE" statement for local variables, and specify
the local variables as "OUTPUT" on the "EXEC" statement. Otherwise,
sybretval will not be able to access the return values. If the return
variable names are to be accessed by sybcols, use the assignment form
of "EXEC", e.g.:
declare @local-var datatype
exec stored-proc @proc-var-name = @local-var output
If a stored procedure is executed with sybsql, and the procedure uses
Transact-SQL "PRINT" statements, check $sybmsg(msgtext) before
executing any other Sybtcl commands. Otherwise, the PRINT output will
be lost on the next command. Multiple PRINT statements are separated
by newlines in $sybmsg(msgtext).
Sybtcl error and message handlers simply populate values in the sybmsg
array. The error handler always returns INT_CANCEL.
To use the -nolog feature of sybwritetext, the following option must
have been set on the database:
sp_dboption 'yourdbname', 'select into/bulkcopy', 'true'
The limit of the number of simultaneous connections is artificial,
based on a fixed table in sybtcl. Change the source #define
SYBTCLPROCS if more are needed.
The maximum amount of TEXT or IMAGE data returned by sybnext is
ultimately dependent on sybtcl's ability to malloc() maxtext bytes of
memory for each TEXT or IMAGE column retrieved. Setting
sybmsg(maxtext) to too high a value may cause core dumps or memory
shortages. Sybreadtext does not malloc() an area to hold the entire
value; instead it retrieves TEXT and IMAGE in chunks and writes to a
file. While maxtext limits the amount of data retrieved by
sybreadtext, it shouldn't cause memory shortages as sybnext might.
When using sybnext with the optional tcl-commands argument, a
substantial performance improvement can be realized by not using the
substitution values (@1, @2, etc.) Instead, specify the substitution
character as a null string {}, and use the tclvar-columnum argument
pairs.
ENVIRONMENT VARIABLES
DSQUERY
The default Sybase server.
SYBASE
The home directory for Sybase files.
FILES
$SYBASE/interfaces - definitions for Sybase Servers.
AUTHOR
Tom Poindexter, Denver Colorado <tpoindex@nyx.net>, Currently
maintained by D. J. Hagberg <dhagberg@millibits.com>. Version 3.0
released December, 2000. The ?commands? option to sybnext was borrowed
from my work with Oratcl, a Tcl interface to the Oracle database
product.
http://sybtcl.sourceforge.net/
http://www.nyx.net/~tpoindex
Sybtcl 3.0 Sybtcl(n)