Difference between revisions of "Sqlite3"

From GiderosMobile
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end
 
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--finalize statement to free resources
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stmt:finalize()
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-- close the database
 
-- close the database
 
db:close()
 
db:close()
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=== Methods ===
 
=== Methods ===
  

Revision as of 23:56, 14 February 2024

Supported platforms: Platform android.pngPlatform ios.pngPlatform mac.pngPlatform pc.pngPlatform html5.pngPlatform winrt.pngPlatform win32.png
Available since: Gideros 2012.2.1

Description

Gideros runtime supports public domain SQLite3 database engine for iOS, Android and Desktop platforms.

require "lsqlite3"
For more information and detailed documentation, please visit [1](http://lua.sqlite.org)

SQLite3 on Android platforms

Currently, LuaSQLite3 plugin cannot open databases stored in APK files. Therefore, database file should be copied from resource directory to documents directory.

To copy a file, this function can be used:

local function copy(src, dst)
	local srcf = io.open(src, "r")
	local dstf = io.open(dst, "wb")
	local size = 2^13 -- good buffer size (8K)
	while true do
		local block = srcf:read(size)
		if not block then break end
		dstf:write(block)
	end
	srcf:close()
	dstf:close()
end

Also it is better to check if the database file is previously copied or not. To check if a file can be found on the underlying file system, this function can be used:

local function exists(file)
	local f = io.open(file, "rb")
	if f == nil then return false end
	f:close()
	return true
end

By using these two function, you can copy the database file from resource to documents directory before using it:

if not exists("|D|database.db") then
	copy("database.db", "|D|database.db")
end

SQLite3 on on WinRT need to add an extension to Visual Studio

Gideros now supports sqlite and to make this work on Windows Phone, it is necessary to add an extension to Visual Studio. Even if you don't use sqlite, you will need to add this extension or Windows Phone projects exported by Gideros will not compile. It's easy to do as explained next. Of course, you only need to add the extension once.

Open Visual Studio and go to TOOLS > Extensions and Updates. Select the Online tab on the left and type sqlite in the search bar at the top right. Select SQLite for Windows 8.1 or/and Windows Phone 8.1 and select install. You will need to restart VS for the extension to take effect.

Example

local sqlite3 = require "lsqlite3"
print(sqlite3.version())
local db = sqlite3.open("db/mydb2.gdb") -- path to your db

db:exec[=[
	CREATE TABLE numbers(num1,num2,text);
]=]

db:exec[=[
	INSERT INTO numbers VALUES(1,101,"a");
	INSERT INTO numbers VALUES(2,202,"b");
	INSERT INTO numbers VALUES(3,303,"c");
]=]
for num1,num2,text in db:urows('SELECT * FROM numbers') do
	print(num1,num2,text)
end

db:close()

Complete Example with SQLite3 binding by Atilim

require "lsqlite3"
 
-- open the database
local db = sqlite3.open("|D|db.sqlite3")
 
-- check if 'numbers' table exists
local exists = false
db:exec("SELECT name FROM sqlite_master WHERE type='table' AND name='numbers'", function() exists = true end)
 
-- if not, create it and put some values
if not exists then
	local sql = [[
		CREATE TABLE numbers(num,str);
		INSERT INTO numbers VALUES(1,'ABC');
		INSERT INTO numbers VALUES(2,'DEF');
		INSERT INTO numbers VALUES(3,'UVW');
		INSERT INTO numbers VALUES(4,'XYZ');
	]]
 
	db:exec(sql)
end
 
-- create a prepared statement
local stmt = db:prepare("SELECT * FROM numbers WHERE num=? AND str=?")
stmt:bind(1, 1)  -- bind 1st value as 1
stmt:bind(2, "ABC")  -- bind 2nd value as "ABC"
 
-- execute and print the result
for num,str in stmt:urows() do
	print(num, str)
end
 
--finalize statement to free resources
stmt:finalize()

-- close the database
db:close()


Methods

Events

Constants