LuaSQLite 3 - a Lua 5.1 wrapper for the SQLite3 library
LuaSQLite 3 is a thin wrapper around the public domain SQLite3 database engine.
The lsqlite3 module supports the creation and manipulation of
SQLite3 databases. After a require('lsqlite3') the exported
functions are called with prefix sqlite3. However, most sqlite3
functions are called via an object-oriented interface to either
database or SQL statement objects; see below for details.
This documentation does not attempt to describe how SQLite3 itself works, it just describes the Lua binding and the available functions. For more information about the SQL features supported by SQLite3 and details about the syntax of SQL statements and queries, please see the SQLite3 documentation http://www.sqlite.org/. Using some of the advanced features (how to use callbacks, for instance) will require some familiarity with the SQLite3 API.
LuaSQLite 3 source code can be downloaded from its LuaForge (http://luaforge.net/projects/luasqlite/) page.
You will also need to build or obtain an SQLite3 loadable library (DLL or .so). See http://www.sqlite.org/ for obtaining SQLite3 source code or downloading a binary SQLite3 library.
A Makefile is provided; it assumes an SQLite3 library is already installed.
The distribution contains an examples directory. The unit tests also show some example use.
The distribution contains some units tests using Michael Roth's
lunit (which is also included). Some of the tests were also derived
from Michael's lua-sqlite3 module, and more unit tests added by
Doug Currie.
The distribution also contains some functional tests by Tiago.
This version of lsqlite3 was tested with SQLite 3.4.2.
sqlite3.complete(sql)
Returns true if the string sql comprises one or more complete SQL
statements and false otherwise.
sqlite3.open(filename)
Opens (or creates if it does not exist) an SQLite database with name
filename and returns its handle as userdata (the returned object
should be used for all further method calls in connection with this
specific database, see Database methods). Example:
myDB=sqlite3.open('MyDatabase.sqlite3') -- open
-- do some database calls...
myDB:close() -- close
In case of an error, the function returns nil, an error code and an error message.
sqlite3.open_memory()
Opens an SQLite database in memory and returns its handle as userdata. In case of an error, the function returns nil, an error code and an error message. (In-memory databases are volatile as they are never stored on disk.)
sqlite3.temp_directory([temp])
Sets or queries the directory used by SQLite for temporary files. If
string temp is a directory name or nil, the temporary directory is
set accordingly and the old value is returned. If temp is missing,
the function simply returns the current temporary directory.
sqlite3.version()
Returns a string with SQLite version information, in the form 'x.y[.z]'.
After opening a database with sqlite3.open() or
sqlite3.open_memory()
the returned database object should be used for all further method calls
in connection with that database. An open database object supports the
following methods.
db:busy_handler([func[,udata]])
Sets or removes a busy handler for a database. func is either a Lua
function that implements the busy handler or nil to remove a previously
set handler. This function returns nothing.
The handler function is called with two parameters: udata and the
number of (re-)tries for a pending transaction. It should return nil,
false or 0 if the transaction is to be aborted. All other values will
result in another attempt to perform the transaction. (See the SQLite
documentation for important hints about writing busy handlers.)
db:busy_timeout(t)
Sets a busy handler that waits for t milliseconds if a transaction
cannot proceed. Calling this function will remove any busy handler set
by db:busy_handler(); calling it with an argument
less than or equal to 0 will turn off all busy handlers.
db:changes()
This function returns the number of database rows that were changed (or
inserted or deleted) by the most recent SQL statement. Only changes that
are directly specified by INSERT, UPDATE, or DELETE statements are
counted. Auxiliary changes caused by triggers are not counted. Use
db:total_changes() to find the total number of
changes.
db:close()
Closes a database. All SQL statements prepared using
db:prepare() should
have been finalized before this function is called. The function returns
sqlite3.OK on success or else a numerical error code (see the list of
Numerical error and result codes).
db:close_vm(temponly)
Finalizes all statements that have not been explicitly finalized. If
temponly is true, only internal, temporary statements are finalized.
This function returns nothing.
db:create_aggregate(name,nargs,step,final)
This function creates an aggregate callback function. Aggregates perform
an operation over all rows in a query. name is a string with the name
of the aggregate function as given in an SQL statement; nargs is the
number of arguments this call will provide. step is the actual Lua
function that gets called once for every row; it should accept a function
context (see Methods for callback contexts) plus the same number of
parameters as given in nargs. final is a function that is called
once after all rows have been processed; it receives one argument, the
function context.
The function context can be used inside the two callback functions to communicate with SQLite3. Here is a simple example:
db:exec[=[
CREATE TABLE numbers(num1,num2);
INSERT INTO numbers VALUES(1,11);
INSERT INTO numbers VALUES(2,22);
INSERT INTO numbers VALUES(3,33);
]=]
local num_sum=0
local function oneRow(context,num) -- add one column in all rows
num_sum=num_sum+num
end
local function afterLast(context) -- return sum after last row has been processed
context:result_number(num_sum)
num_sum=0
end
db:create_aggregate("do_the_sums",1,oneRow,afterLast)
for sum in db:urows('SELECT do_the_sums(num1) FROM numbers') do print("Sum of col 1:",sum) end
for sum in db:urows('SELECT do_the_sums(num2) FROM numbers') do print("Sum of col 2:",sum) end
This prints:
Sum of col 1: 6
Sum of col 2: 66
db:create_collation(name,func)
This creates a collation callback. A collation callback is used to
establish a collation order, mostly for string comparisons and sorting
purposes. name is a string with the name of the collation to be created;
func is a function that accepts two string arguments, compares them
and returns 0 if both strings are identical, -1 if the first argument is
lower in the collation order than the second and 1 if the first argument
is higher in the collation order than the second. A simple example:
local function collate(s1,s2)
s1=s1:lower()
s2=s2:lower()
if s1==s2 then return 0
elseif s1<s2 then return -1
else return 1 end
end
db:exec[=[
CREATE TABLE test(id INTEGER PRIMARY KEY,content COLLATE CINSENS);
INSERT INTO test VALUES(NULL,'hello world');
INSERT INTO test VALUES(NULL,'Buenos dias');
INSERT INTO test VALUES(NULL,'HELLO WORLD');
]=]
db:create_collation('CINSENS',collate)
for row in db:nrows('SELECT * FROM test') do print(row.id,row.content) end
db:create_function(name,nargs,func)
This function creates a callback function. Callback function are called
by SQLite3 once for every row in a query. name is a string with the
name of the callback function as given in an SQL statement; nargs is
the number of arguments this call will provide. func is the actual Lua
function that gets called once for every row; it should accept a
function context (see Methods for callback contexts) plus the same
number of parameters as given in nargs. Here is an example:
db:exec'CREATE TABLE test(col1,col2,col3)'
db:exec'INSERT INTO test VALUES(1,2,4)'
db:exec'INSERT INTO test VALUES(2,4,9)'
db:exec'INSERT INTO test VALUES(3,6,16)'
db:create_function('sum_cols',3,function(ctx,a,b,c)
ctx:result_number(a+b+c)
end))
for col1,col2,col3,sum in db:urows('SELECT *,sum_cols(col1,col2,col3) FROM test') do
util.printf('%2i+%2i+%2i=%2i\n',col1,col2,col3,sum)
end
db:errcode()
db:error_code()
Returns the numerical result code (or extended result code) for the most recent failed call associated with database db. See Numerical error and result codes for details.
db:errmsg()
db:error_message()
Returns a string that contains an error message for the most recent failed call associated with database db.
db:exec(sql[,func[,udata]])
db:execute(sql[,func[,udata]])
Compiles and executes the SQL statement(s) given in string sql. The
statements are simply executed one after the other and not stored. The
function returns sqlite3.OK on success or else a numerical error code
(see Numerical error and result codes).
If one or more of the SQL statements are queries, then the callback
function specified in func is invoked once for each row of the query
result (if func is nil, no callback is invoked). The callback receives
four arguments: udata (the third parameter of the db:exec() call),
the number of columns in the row, a table with the column values and
another table with the column names. The callback function should return
0. If the callback returns a non-zero value then the query is aborted,
all subsequent SQL statements are skipped and db:exec() returns
sqlite3.ABORT. Here is a simple example:
sql=[=[
CREATE TABLE numbers(num1,num2,str);
INSERT INTO numbers VALUES(1,11,"ABC");
INSERT INTO numbers VALUES(2,22,"DEF");
INSERT INTO numbers VALUES(3,33,"UVW");
INSERT INTO numbers VALUES(4,44,"XYZ");
SELECT * FROM numbers;
]=]
function showrow(udata,cols,values,names)
assert(udata=='test_udata')
print('exec:')
for i=1,cols do print('',names[i],values[i]) end
return 0
end
db:exec(sql,showrow,'test_udata')
db:interrupt()
This function causes any pending database operation to abort and return at the next opportunity. This function returns nothing.
db:isopen()
Returns true if database db is open, false otherwise.
db:last_insert_rowid()
This function returns the rowid of the most recent INSERT into the database. If no inserts have ever occurred, 0 is returned. (Each row in an SQLite table has a unique 64-bit signed integer key called the 'rowid'. This id is always available as an undeclared column named ROWID, OID, or _ROWID_. If the table has a column of type INTEGER PRIMARY KEY then that column is another alias for the rowid.)
If an INSERT occurs within a trigger, then the rowid of the inserted row is returned as long as the trigger is running. Once the trigger terminates, the value returned reverts to the last value inserted before the trigger fired.
db:nrows(sql)
Creates an iterator that returns the successive rows selected by the SQL
statement given in string sql. Each call to the iterator returns a
table in which the named fields correspond to the columns in the database.
Here is an example:
db:exec[=[
CREATE TABLE numbers(num1,num2);
INSERT INTO numbers VALUES(1,11);
INSERT INTO numbers VALUES(2,22);
INSERT INTO numbers VALUES(3,33);
]=]
for a in db:nrows('SELECT * FROM numbers') do table.print(a) end
This script prints:
num2: 11
num1: 1
num2: 22
num1: 2
num2: 33
num1: 3
db:prepare(sql)
This function compiles the SQL statement in string sql into an internal
representation and returns this as userdata. The returned object should
be used for all further method calls in connection with this specific
SQL statement (see Methods for prepared statements).
db:progress_handler(n,func,udata)
This function installs a callback function func that is invoked
periodically during long-running calls to db:exec()
or stmt:step(). The
progress callback is invoked once for every n internal operations,
where n is the first argument to this function. udata is passed to
the progress callback function each time it is invoked. If a call to
db:exec() or stmt:step() results in fewer than n operations
being executed, then the progress callback is never invoked. Only a
single progress callback function may be registered for each opened
database and a call to this function will overwrite any previously set
callback function. To remove the progress callback altogether, pass nil
as the second argument.
If the progress callback returns a result other than 0, then the current
query is immediately terminated, any database changes are rolled back
and the containing db:exec() or stmt:step() call returns
sqlite3.INTERRUPT. This feature can be used to cancel long-running
queries.
db:rows(sql)
Creates an iterator that returns the successive rows selected by the SQL
statement given in string sql. Each call to the iterator returns a table
in which the numerical indices 1 to n correspond to the selected columns
1 to n in the database. Here is an example:
db:exec[=[
CREATE TABLE numbers(num1,num2);
INSERT INTO numbers VALUES(1,11);
INSERT INTO numbers VALUES(2,22);
INSERT INTO numbers VALUES(3,33);
]=]
for a in db:rows('SELECT * FROM numbers') do table.print(a) end
This script prints:
1: 1
2: 11
1: 2
2: 22
1: 3
2: 33
db:total_changes()
This function returns the number of database rows that have been
modified by INSERT, UPDATE or DELETE statements since the database was
opened. This includes UPDATE, INSERT and DELETE statements executed as
part of trigger programs. All changes are counted as soon as the
statement that produces them is completed by calling either
stmt:reset() or stmt:finalize().
db:trace(func,udata)
This function installs a trace callback handler. func is a Lua
function that is called by SQLite3 just before the evaluation of an SQL
statement. This callback receives two arguments: the first is the
udata argument used when the callback was installed; the second is a
string with the SQL statement about to be executed.
db:urows(sql)
Creates an iterator that returns the successive rows selected by the SQL
statement given in string sql. Each call to the iterator returns the
values that correspond to the columns in the currently selected row.
Here is an example:
db:exec[=[
CREATE TABLE numbers(num1,num2);
INSERT INTO numbers VALUES(1,11);
INSERT INTO numbers VALUES(2,22);
INSERT INTO numbers VALUES(3,33);
]=]
for num1,num2 in db:urows('SELECT * FROM numbers') do print(num1,num2) end
This script prints:
1 11
2 22
3 33
After creating a prepared statement with db:prepare()
the returned statement object should be used for all further calls in
connection with that statement. Statement objects support the following
methods.
stmt:bind(n[,value])
Binds value to statement parameter n. If the type of value is string
or number, it is bound as text or double, respectively. If value is a
boolean or nil or missing, any previous binding is removed. The function
returns sqlite3.OK on success or else a numerical error code (see
Numerical error and result codes).
stmt:bind_blob(n,blob)
Binds string blob (which can be a binary string) as a blob to
statement parameter n. The function returns sqlite3.OK on success
or else a numerical error code (see Numerical error and result codes).
stmt:bind_names(nametable)
Binds the values in nametable to statement parameters. If the
statement parameters are named (i.e., of the form ``:AAA'' or ``$AAA'')
then this function looks for appropriately named fields in nametable;
if the statement parameters are
not named, it looks for numerical fields 1 to the number of statement
parameters. The function returns sqlite3.OK on success or else a
numerical error code (see Numerical error and result codes).
stmt:bind_parameter_count()
Returns the largest statement parameter index in prepared statement
stmt. When the statement parameters are of the forms ``:AAA'' or ``?'',
then they are assigned sequentially increasing numbers beginning with
one, so the value returned is the number of parameters. However if the
same statement parameter name is used multiple times, each occurrence
is given the same number, so the value returned is the number of unique
statement parameter names.
If statement parameters of the form ``?NNN'' are used (where NNN is an integer) then there might be gaps in the numbering and the value returned by this interface is the index of the statement parameter with the largest index value.
stmt:bind_parameter_name(n)
Returns the name of the n-th parameter in prepared statement stmt.
Statement parameters of the form ``:AAA'' or ``@AAA'' or ``$VVV'' have a name
which is the string ``:AAA'' or ``@AAA'' or ``$VVV''. In other words, the
initial ``:'' or ``$'' or ``@'' is included as part of the name. Parameters
of the form ``?'' or ``?NNN'' have no name. The first bound parameter has
an index of 1.
If the value n is out of range or if the n-th parameter is
nameless, then nil is returned. The function returns sqlite3.OK on
success or else a numerical error code (see
Numerical error and result codes)
stmt:bind_values(value1,value2,...,valueN)
Binds the given values to statement parameters. The function returns
sqlite3.OK on success or else a numerical error code (see
Numerical error and result codes).
stmt:columns()
Returns the number of columns in the result set returned by statement stmt or 0 if the statement does not return data (for example an UPDATE).
stmt:finalize()
This function frees prepared statement stmt. If the statement was
executed successfully, or not executed at all, then sqlite3.OK is
returned. If execution of the statement failed then an error code is
returned.
stmt:get_name(n)
Returns the name of column n in the result set of statement stmt. (The
left-most column is number 0.)
stmt:get_named_types()
Returns a table with the names and types of all columns in the result set of statement stmt.
stmt:get_named_values()
This function returns a table with names and values of all columns in the current result row of a query.
stmt:get_names()
This function returns an array with the names of all columns in the result set returned by statement stmt.
stmt:get_type(n)
Returns the type of column n in the result set of statement stmt. (The
left-most column is number 0.)
stmt:get_types()
This function returns an array with the types of all columns in the result set returned by statement stmt.
stmt:get_unames()
This function returns a list with the names of all columns in the result set returned by statement stmt.
stmt:get_utypes()
This function returns a list with the types of all columns in the result set returned by statement stmt.
stmt:get_uvalues()
This function returns a list with the values of all columns in the current result row of a query.
stmt:get_value(n)
Returns the value of column n in the result set of statement stmt. (The
left-most column is number 0.)
stmt:get_values()
This function returns an array with the values of all columns in the result set returned by statement stmt.
stmt:isopen()
Returns true if stmt has not yet been finalized, false otherwise.
stmt:nrows()
Returns an function that iterates over the names and values of the
result set of statement stmt. Each iteration returns a table with the
names and values for the current row.
This is the prepared statement equivalent of db:nrows().
stmt:reset()
This function resets SQL statement stmt, so that it is ready to be
re-executed. Any statement variables that had values bound to them using
the stmt:bind*() functions retain their values.
stmt:rows()
Returns an function that iterates over the values of the result set of
statement stmt. Each iteration returns an array with the values for the
current row.
This is the prepared statement equivalent of db:rows().
stmt:step()
This function must be called to evaluate the (next iteration of the) prepared statement stmt. It will return one of the following values:
sqlite3.BUSY: the engine was unable to acquire the locks needed. If the
statement is a COMMIT or occurs outside of an explicit transaction, then
you can retry the statement. If the statement is not a COMMIT and occurs
within a explicit transaction then you should rollback the transaction
before continuing.
sqlite3.DONE: the statement has finished executing successfully.
stmt:step() should not be called again on this statement
without first calling stmt:reset() to reset the virtual
machine back to the initial state.
sqlite3.ROW: this is returned each time a new row of data is ready for
processing by the caller. The values may be accessed using the column
access functions. stmt:step() can be called again to
retrieve the next row of data.
sqlite3.ERROR: a run-time error (such as a constraint violation) has
occurred. stmt:step() should not be called again. More
information may be found by calling db:errmsg(). A more
specific error
code (can be obtained by calling stmt:reset().
sqlite3.MISUSE: the function was called inappropriately, perhaps
because the statement has already been finalized or a previous call to
stmt:step() has returned sqlite3.ERROR or
sqlite3.DONE.
stmt:urows()
Returns an function that iterates over the values of the result set of
statement stmt. Each iteration returns the values for the current row.
This is the prepared statement equivalent of db:urows().
A callback context is available as a parameter inside the callback
functions db:create_aggregate() and
db:create_function(). It can be used
to get further information about the state of a query.
context:aggregate_count()
Returns the number of calls to the aggregate step function.
context:get_aggregate_data()
Returns the user-definable data field for callback funtions.
context:set_aggregate_data(udata)
Set the user-definable data field for callback funtions to udata.
context:result(res)
This function sets the result of a callback function to res. The type of the result depends on the type of res and is either a number or a string or nil. All other values will raise an error message.
context:result_null()
This function sets the result of a callback function to nil. It returns nothing.
context:result_number(number)
context:result_double(number)
This function sets the result of a callback function to the value
number. It returns nothing.
context:result_int(number)
This function sets the result of a callback function to the integer
value in number. It returns nothing.
context:result_text(str)
This function sets the result of a callback function to the string in
str. It returns nothing.
context:result_blob(blob)
This function sets the result of a callback function to the binary
string in blob. It returns nothing.
context:result_error(err)
This function sets the result of a callback function to the error value
in err. It returns nothing.
context:user_data()
Returns the userdata parameter given in the call to install the callback
function (see db:create_aggregate() and
db:create_function() for details).
The following constants are defined by module sqlite3:
OK: 0 ERROR: 1 INTERNAL: 2 PERM: 3 ABORT: 4
BUSY: 5 LOCKED: 6 NOMEM: 7 READONLY: 8 INTERRUPT: 9
IOERR: 10 CORRUPT: 11 NOTFOUND: 12 FULL: 13 CANTOPEN: 14
PROTOCOL: 15 EMPTY: 16 SCHEMA: 17 TOOBIG: 18 CONSTRAINT: 19
MISMATCH: 20 MISUSE: 21 NOLFS: 22 FORMAT: 24 RANGE: 25
NOTADB: 26 ROW: 100 DONE: 101
For details about their exact meaning please see the SQLite3 documentation http://www.sqlite.org/.
This is lsqlite3 subversion 6, also known as ``devel-0.6''.
lsqlite3 was developed by Tiago Dionizio and Doug Currie with
contributions from Thomas Lauer and Michael Roth.
This documentation is based on the ``(very) preliminary'' documents for the Idle-SQLite3 database module. Thanks to Thomas Lauer for making it available.
/************************************************************************
* lsqlite3 *
* Copyright (C) 2002-2007 Tiago Dionizio, Doug Currie *
* All rights reserved. *
* Author : Tiago Dionizio <tiago.dionizio@ist.utl.pt> *
* Author : Doug Currie <doug.currie@alum.mit.edu> *
* Library : lsqlite3 - a SQLite 3 database binding for Lua 5 *
* *
* Permission is hereby granted, free of charge, to any person obtaining *
* a copy of this software and associated documentation files (the *
* "Software"), to deal in the Software without restriction, including *
* without limitation the rights to use, copy, modify, merge, publish, *
* distribute, sublicense, and/or sell copies of the Software, and to *
* permit persons to whom the Software is furnished to do so, subject to *
* the following conditions: *
* *
* The above copyright notice and this permission notice shall be *
* included in all copies or substantial portions of the Software. *
* *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, *
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY *
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, *
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE *
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
************************************************************************/