mysqltcl(n) 3.0 ""
mysqltcl - MySQL server access commands for Tcl
TABLE OF
CONTENTS
SYNOPSIS
DESCRIPTION
MYSQLTCL
COMMANDS
STATUS
INFORMATION
Backward
compatibility
BUGS
& POSSIBLE MISFEATURES
AUTHORS
package require Tcl 8.4
package require mysqltcl 3.0
MySQLTcl is a collection of Tcl commands and a Tcl global array that provide
access to MySQL database servers.
MySQLTcl is nothing more than a patched version of a patched version of Hakan
Soderstrom's patch of Tom Poindexter's Sybtcl.
Mysqltcl is binary Tcl library (extension) written in C language that use
direkt official MySQL C-API. Almost all Tcl commands correspond to MySQL C-API
functions. For detail documentation see official MySQL C-API manual.
- ::mysql::connect ?option
value...?
- Connect to a MySQL server. A handle is returned which should be used in
other mysqltcl commands using this connection. ::mysql::connect raises a Tcl
error if the connection fails. ::mysql::connect read first the options from
my.cnf file group mysqltcl. See MySQL documentation chapter "options files".
Possible connection options are:
- -host hostname
- The host on which the server is located. The local host is used by
default.
- -user user
- The user whose name is used for the connection. The current Unix
user-name is used by default.
- -password password
- The password that must be used for the connection. If it is not present,
the connection is possible only for users with no password on the server.
- -db db
- If this option is present, db is used as current
database, with no need for a call to mysql::use.
- -port port
- The port number for the TCP/IP connection, if it's different from the
default.
- -socket socket
- The socket or named pipe for the connection.
- -encoding encodingname
- The option works similar to -encoding option in fconfigure. It support
also special encoding name binary. By option -binary no converting will be
done be reading or writing to/from MySQL. If option is not set the system
encoding (see utf-8) is used. Please test all input and outputs with another
program to check that all is the way you expect it. If option binary is not
used the system procedures Tcl_ExternalToUtfDString (writing) and
Tcl_ExternalToUtf (reading) will be used by option binary the function
Tcl_GetByteArrayFromObj and Tcl_NewByteArrayObj are used. If you want to
manipulate binary date use -encoding binary. By handling textes set your
special encoding that you want to use in your database. Consider what
another system access the database and what encoding they expect. It can
useful to use -encoding utf-8. That is standard encoding in some linux
distributions and newer systems.
- -compress boolean
- Use compression protocol. Default is false
- -odbc boolean
- The client is an ODBC client. This changes mysqld to be more
ODBC-friendly. Default is false
- -noschema boolean
- Don't allow the db_name.tbl_name.col_name syntax. This is for ODBC. It
causes the parser to generate an error if you use that syntax, which is
useful for trapping bugs in some ODBC programs. This changes mysqld to be
more ODBC-friendly. Default is false
- -multistatement boolean
- Tell the server that the client may send multiple-row-queries (separated
by `;'). If this flag is not set, multiple-row-queries are disabled. Default
is false.
- -multiresult boolean
- Tell the server that the client can handle multiple-result sets from
multi-queries or stored procedures. This is automatically set if
CLIENT_MULTI_STATEMENTS is set.
- -localfiles boolean
- Enable LOAD DATA LOCAL handling. Default is false.
- -foundrows boolean
- Return the number of found (matched) rows, not the number of affected
rows. Default is false.
- -interactive boolean
- Allow interactive_timeout seconds (instead of wait_timeout seconds) of
inactivity before closing the connection. The client's session wait_timeout
variable will be set to the value of the session interactive_timeout
variable. Default is false.
- -ssl boolean
- Switch to SSL after handshake. Default is false
- -sslkey string
- is the pathname to the key file. Used if -ssl is true
- -sslcert string
- is the pathname to the certificate file. Used if -ssl is true
- -sslca string
- is the pathname to the certificate authority file. Used if -ssl is true
- -sslcapath string
- is the pathname to a directory that contains trusted SSL CA certificates
in pem format. Used if -ssl is true
- -sslcipher string
- is a list of allowable ciphers to use for SSL encryption. Used if -ssl
is true
- ::mysql::use handle database
- Associate a connected handle with a particular database. handle must be a valid handle previously obtained from
::mysql::connect. mysql::use raises a Tcl error if the handle is not valid or
if the database name specified could not be used.
Consider you can use
mysqltcl without to specify the database, in this case you must use explizit
schema notation to specify the table in sql.
| |
::mysql::sel $handle {select * from uni.student}
|
with option connection -noschema you can prohibit such syntax.
- ::mysql::sel handle sql-statement ?-list|-flatlist?
- Send sql-statement to the server.
If sql-statement is a SELECT statement and no -list or -flatlist option is specified, the
command returns the number of rows returned as the result of the query. The
rows can be obtained by the ::mysql::fetch and/or the ::mysql::map commands. The resulting rows are called the
pending result.
If sql-statement is a SELECT
statement and -list or -flatlist is
specified, the command returns the full list of rows returned as the result of
the query in one of two possible formats:
- -list
- generates a list of lists, in which each element is a row of the result.
- -flatlist
- generates the concatenation of all rows in a single list, which is
useful for scanning with a single foreach.
Example:
| |
% ::mysql::sel $db "SELECT ID, NAME FROM FRIENDS" -list
{1 Joe} {2 Phil} {3 John}
% ::mysql::sel $db "SELECT ID, NAME FROM FRIENDS" -flatlist
{1 Joe 2 Phil 3 John}
|
Note that both list syntaxes are faster
than something like
| |
% ::mysql::sel $db "SELECT ID, NAME FROM FRIENDS"
% ::mysql::map $db {id name} {lappend result $id $name}
% set $result
{1 Joe 2 Phil 3 John}
|
If sql-statement is a
valid MySQL statement, but not a SELECT statement, the command returns -1
after executing the statement, or an empty string if -list or
-flatlist is specified. There is no pending result in this
case.
In any case ::mysql::sel implicitly cancels any previous result
still pending for the handle.
- ::mysql::fetch handle
- Returns the next row from result set as Tcl list. mysql::fetch raises a
Tcl error if there is no pending result for handle.
mysql::fetch was former named mysqlnext.
- ::mysql::exec handle sql-statement
- Send sql-statement, a MySQL non-SELECT statement, to the
server. The handle must be in use (through ::mysql::connect
and ::mysql::use).
::mysql::exec implicitly cancels any previous
result pending for the handle.
If sql-statement is a
valid MySQL SELECT statement, the statement is executed, but the result is
discarded. No Tcl error is generated. This amounts to a (potentially costly)
no-op. Use the ::mysql::sel command for SELECT statements.
::mysql::exec return the number of affected rows (DELETE, UPDATE)
- ::mysql::query handle sql-select-statement
- Send sql-select-statement to the server.
mysql::query allow to send multiple nested queries on one handle
(without need to build new handle or caching results). mysql::query return a
query handle that can be used as handle in commands as (mysql::fetch,
::mysql::map, mysql::seek, mysql::col, mysql::result). After result proceeding
all query must be freed with ::mysql::endquery query-hanlde command.
Example:
| |
set query1 [::mysql::query $db {SELECT ID, NAME FROM FRIENDS}\]
while {[set row [::mysql::fetch $query1]]!=""} {
set id [lindex $row 0]
set query2 [::mysql::query $db "SELECT ADDRESS FROM ADDRESS WHERE FRIENDID=$ID"]
::mysql::map $query2 address { puts "address = $address" }
::mysql::endquery $query2
}
::mysql::endquery $query1
|
In most cases one should use sql-joins and
avoid nested queries. SQL-sever can optimize such queries. But in some
applications (GUI-Forms) where the results are used long time the inner query
is not known before.
- ::mysql::endquery query-handle
- free result memory after ::mysql::query command. You must
invoke ::mysql::endquery after each mysqlquery to not cause memory leaks. See
mysqlquery command.
Using ::mysql::endquery on
db-handle will free also memory (pending result) after ::mysql::sel command.
- ::mysql::map handle binding-list script
- Iterate a script over the rows of the pending result. ::mysql::map may
consume all rows or only some of the rows of the pending result. Any remaining
rows may be obtained by further ::mysql::fetch or ::mysql::map commands.
handle must be a handle with a pending result from a
previous ::mysql::sel command. binding-list must be a list of
one or more variable names. script must be a Tcl script. It
may be empty, but usually it contains one or more commands.
::mysql::map processes one row at a time from the pending result. For
each row the column values are bound to the variables in the binding list,
then the script is executed. Binding is strictly positional. The first
variable in the binding list is bound to the first column of the row, and so
on. The variables are created in the current context (if they do not already
exist). A variable name begining with a hyphen is not bound; it serves as a
placeholder in the binding list. If there are more columns than variables the
extra columns are ignored.
The ::mysql::map command is similar to an
ordinary foreach. A foreach iterates over the elements of a
list, ::mysql::map iterates over the rows of a pending result. In both cases
iteration is affected by break and continue Tcl commands.
The binding list variables retain their last values after the command has
completed.
A simple example follows. Assume $db is a handle in use.
| |
::mysql::sel $db {
select lname, fname, area, phone from friends order by lname, fname
}
::mysql::map $db {ln fn - phone} {
if {$phone == {}} continue
puts [format "%16s %-8s %s" $ln $fn $phone]
}
|
The ::mysql::sel command gets and sorts
all rows from table friends. The ::mysql::map command is used to format and
print the result in a way suitable for a phone list. For demonstration
purposes one of the columns (area) is not used. The script begins by skipping
over rows which have no phone number. The second command in the script formats
and prints values from the row.
::mysql::map raises a Tcl error if
there is no pending result for handle, or if binding-list contains more variables than there are columns in
the pending result.
- ::mysql::receive handle sql-statment binding-list script
- This command works the same way as the command mysqtclmap but it do not
need leading ::mysql::sel command. The main difference is internal using of
MySQL client library. This command use mysql_use_result from C-API that do not
store result on client but try to receive the rows directly from server. There
is also no client cache. This command can be faster as using of ::mysql::sel
and by very big resultset will not overload client machine. The scipt should
process the result immadiatly because it can block table (or tables) for
another clients. If performance matter please test all alternatives separatly.
You must consider two aspects: memory consumption and performance.
- ::mysql::seek handle row-index
- Moves the current position among the rows in the pending result. This may
cause ::mysql::fetch and ::mysql::map to re-read rows, or to
skip over rows.
Row index 0 is the position just before the first row
in the pending result; row index 1 is the position just before the second row,
and so on. You may specify a negative row index. Row index -1 is the position
just before the last row; row index -2 is the position just before the second
last row, and so on. An out-of-bounds row index will cause ::mysql::seek to
set the new current position either just before the first row (if the index is
too negative), or just after the last row (if the index exceeds the number of
rows). This is not an error condition.
::mysql::seek returns the
number of rows that can be read sequentially from the new current position.
::mysql::seek raises a Tcl error if there is no pending result for handle.
Portability note: The functionality of ::mysql::seek is frequently absent in other Tcl extensions for
SQL. That is because MySQL C-API client library ofers own result set caching
functionality that lacks another SQL-APIs. That increase the performance
because all rows are received at once and the query does not block the server
for another clienst , on the other hand you works on the cached data can use a
lot of memory and are up to date only in the moment of query but not fetch.
- ::mysql::col handle table-name option
-
- ::mysql::col handle table-name optionkist
-
- ::mysql::col handle ?option...?
- Return information about the columns of a table. handle
must be in use. table-name must be the name of a table; it
may be a table name or -current if there is a pending result.
One or more options control what information to return. Each option must be
one of the following keywords.
- name
- Return the name of a column.
- type
- Return the type of a column; one of the strings decimal,
tiny, short, long, float,
double, null, timestamp, long long,
int24, date, time, date time,
year, new date, enum, set, tiny
blob, medium blob, long blob, blob, var
string, or string. Note that a column of type char
will return tiny, while they are represented equally.
- length
- Return the length of a column in bytes.
- table
- Return the name of the table in which this column occurs.
- non_null
- Return the string "1" if the column is non-null; otherwise "0".
- prim_key
- Return the string "1" if the column is part of the primary key;
otherwise "0".
- numeric
- Return the string "1" if the column is numeric; otherwise "0".
- decimals
- Return the string "1" if the column is non-null; otherwise "0".
The three forms of this command generate their result in a
particular way.
- If a single option is present the result is a simple list of values; one
for each column.
- If the options are given in the form of an option list the result is a
list of lists. Each sublist corresponds to a column and contains the
information specified by the options.
- If several options are given, but not in a list, the result is also a
list of lists. In this case each sublist corresponds to an option and
contains one value for each column.
The following is a sample
interactive session containing all forms of the ::mysql::col command and their
results. The last command uses the -current option. It could
alternatively specify the table name explicitly.
| |
%::mysql::col $db friends name
name lname area phone
% ::mysql::col $db friends {name type length}
{fname char 12} {lname char 20} {area char 5} {phone char 12}
% ::mysql::sel $db {select * from friends}
% ::mysql::col $db -current name type length
{fname lname area phone} {char char char char} {12 20 5 12}]
|
- ::mysql::info handle option
- Return various database information depending on the option. The option must be one of the following keywords.
- info
- Return a String with information about last operation. "Records: 3
Duplicates: 0 Warnings: 0" by INSERT or "Rows matched: 40 Changed: 40
Warnings: 0" by UPDATE statements (read the manual for mysql_info in MySQL C
API documentation)
- databases
- Return a list of all database names known to the server. The handle must
be connected.
- dbname
- Return the name of the database with which the handle is associated. The
handle must be in use.
- dbname?
- Return the name of the database with which the handle is associated; an
empty string if the handle is connected, but not in use.
- host
- Return the name of the host to which the handle is connected. The handle
must be connected.
- host
- Return the name of the host to which the handle is connected; an empty
string if the handle is not valid.
- tables
- Return a list of all table names in the database with which the handle
is associated. The handle must be in use.
- serverversion
- Returns the version number of the server as a string.
- serverversionid
- Returns the version number of the server as an integer.
- sqlstate
- Returns a string containing the SQLSTATE error code for the last error.
The error code consists of five characters. '00000' means ``no error.'' The
values are specified by ANSI SQL and ODBC. Note that not all MySQL errors
are yet mapped to SQLSTATE's. The value 'HY000' (general error) is used for
unmapped errors.
- state
- Returns a character string containing information similar to that
provided by the mysqladmin status command. This includes uptime in seconds
and the number of running threads, questions, reloads, and open tables.
- ::mysql::baseinfo option
- return information information that do not need handle.
- connectparameters
- return all supported connecting options
- clientversion
- return the version of underlying MYSQL C-API library
- ::mysql::ping handle
- Checks whether the connection to the server is working. If it has gone
down, an automatic reconnection is attempted.
This function can be
used by clients that remain idle for a long while, to check whether the server
has closed the connection and reconnect if necessary.
Return True if
server is alive
- ::mysql::changeuser user password ?database?
- Changes the user and causes the database specified by database to become
the default (current) database on the connection specified by MySQL. In
subsequent queries, this database is the default for table references that do
not include an explicit database specifier.
::mysql::changeuser fails
unless the connected user can be authenticated or if he doesn't have
permission to use the database. In this case the user and database are not
changed
if database parameter may be set were is no default database.
Cause Error if operation is not succesed
- ::mysql::result handle option
- Return information about the pending result. Note that a result is pending
until canceled by a ::mysql::exec command, even if no rows remain to be read.
Option must be one of the following keywords.
- cols
- Return the number of columns in the pending result. There must be a
pending result.
- cols
- Return the number of columns in the pending result; an empty string if
no result is pending.
- current
- Return the current position in the pending result; a non-negative
integer. This value can be used as row-index in the
::mysql::seek command. An error is raised if there is no pending result.
- current?
- As above, but returns an empty string if there is no pending result.
- rows
- Return the number of rows that can be read sequentially from the current
position in the pending result. There must be a pending result.
- rows
- Return the number of rows that can be read sequentially from the current
position in the pending result; an empty string if no result is pending.
[::mysql::result $db current] + [::mysql::result $db rows] always
equals the total number of rows in the pending result.
- ::mysql::state handle ?-numeric?
- Return the state of a handle as a string or in numeric form. There is no
requirement on handle; it may be any string. The return value
is one of the following strings, or the corresponding numeric value if -numeric is specified. The states form a progression where each
state builds on the previous.
- NOT_A_HANDLE (0)
- The string supplied for handle is not a mysqltcl handle
at all.
- UNCONNECTED (1)
- The string supplied for handle is one of the possible
mysqltcl handles, but it is not valid to any server.
- CONNECTED (2)
- The handle is connected to a server, but not associated with a database.
- IN_USE (3)
- The handle is connected and associated with a database, but there is no
pending result.
- RESULT_PENDING (4)
- The handle is connected, associated with a database, and there is a
pending result.
- ::mysql::close ?handle?
- Closes the server connection associated with handle,
causing it to go back to the unconnected state. Closes all connections if handle is omitted. Returns an empty string. ::mysql::close
raises a Tcl error if a handle is specified which is not valid.
- ::mysql::insertid handle
- Returns the auto increment id of the last INSERT statement.
- ::mysql::escape ?handle? string
- Returns the content of string, with all special
characters escaped, so that it is suitable for use in an SQL statement. This
is simpler (faster) than using a general regexp or string map. If
handle is specified C-API function mysql_real_escape_string is used. This is
the recommended usage because in this case current character set is respected.
- ::mysql::autocommit handle boolean
- Sets autocommit mode on if mode is 1, off if mode is 0.
- ::mysql::commit handle
- Commits the current transaction.
- ::mysql::rollback handle
- Rollback the current transaction.
- ::mysql::nextresult handle
- If more query results exist, mysql::nextresult() reads the next query
results and returns the status back to application. returns -1 if no result or
number of rows in the result set.
- ::mysql::moreresult handle
- Returns true if more results exist from the currently executed query, and
the application must call mysql::result to fetch the results.
- ::mysql::warningcount handle
- Returns the number of warnings generated during execution of the previous
SQL statement.
- ::mysql::isnull value
- Null handling is a known problem with Tcl, especially with DB interaction.
The mysql "varchar" type has two valid blank values, NULL and an empty string.
This is where the problem arises; Tcl is not able to differentiate between the
two because of the way it handles strings. Mysql has new internal Tcl type for
null that string representation is stored in global array mysqltcl(nullvalue)
and as default empty string. mysql::isnull can be used for safe check for null
value. Warning mysql::isnull works only reliable if there are no type
conversation on returned rows. Consider row is always Tcl list even when there
are only one column in the row.
| |
set row [::mysql::next $handle]
if {[mysql::isnull [lindex $row 1]]} {
puts "2. column of $row is null"
}
if {[mysql::isnull $row]} {
puts "this does not work, because of type conversation list to string"
}
|
- ::mysql::newnull
- create new null object. It can be used to simulate returned row contents.
- ::mysql::setserveroption handle option
- there are only 2 options now: -multi_statment_on and -multi_statment_off
- ::mysql::shutdown handle
- Asks the database server to shut down. The connected user must have
SHUTDOWN privileges.
- ::mysql::encoding handle
?encoding?
- Ask or change a encoding of connection. There are special encoding
"binary" for binary data transfers.
Mysqltcl creates and maintains a Tcl global array to provide status
information. Its name is mysqlstatus. .P Mysqlstatus elements:
- code
- A numeric conflict code set after every mysqltcl command. Zero means no
conflict; non-zero means some kind of conflict. All conflicts also generate a
Tcl error.
All MySQL server conflicts set mysqlstatus(code) to the
numeric code of the MySQL error.
Any other conflict sets
mysqlstatus(code) to -1.
- command
- The last failing mysqltcl command. Not updated for successful commands.
- message
- Message string for the last conflict detected. The same string is returned
as the result of the failing mysqltcl command. Not updated for successful
commands.
- nullvalue
- The string to use in query results to represent the SQL null value. The
empty string is used initially. You may set it to another value.
Up from version 3.0 all mysql commands are declared in ::mysql namespace. All
names for example mysqlconnect are also aviable but deprecated. All old commands
have the name pattern mysql{name} and the most of them are now mysql::{name}.
The exception is mysqlnext, which was renamed to mysql::fetch.
Deleting any of the mysqltcl commands closes all connections.
- Tobias Ritzau
- Paolo Brutti
- Artur Trzewik (mail@xdobry.de) - active maintainer
MySQLTcl is
derived from a patch of msql by Hakan Soderstrom, Soderstrom
Programvaruverkstad, S-12242 Enskede, Sweden. msql is derived from Sybtcl by Tom
Poindexter. There are many contributors and bug reporter that are not mentioned.
If you have contributed to mysqltcl and wants to be on the list contact Artur
Trzewik.