客服电话
APP下载
迪恩网络APP
随时随地掌握行业动态
官方微信
扫描二维码
关注迪恩网络微信公众号
开源软件名称：sql-js/sql.js开源软件地址：https://github.com/sql-js/sql.js开源编程语言：JavaScript 85.5%开源软件介绍：
SQLite compiled to JavaScript
sql.js is a javascript SQL database. It allows you to create a relational database and query it entirely in the browser. You can try it in this online demo. It uses a virtual database file stored in memory, and thus doesn't persist the changes made to the database. However, it allows you to import any existing sqlite file, and to export the created database as a JavaScript typed array. sql.js uses emscripten to compile SQLite to webassembly (or to javascript code for compatibility with older browsers). It includes contributed math and string extension functions. sql.js can be used like any traditional JavaScript library. If you are building a native application in JavaScript (using Electron for instance), or are working in node.js, you will likely prefer to use a native binding of SQLite to JavaScript. A native binding will not only be faster because it will run native code, but it will also be able to work on database files directly instead of having to load the entire database in memory, avoiding out of memory errors and further improving performances. SQLite is public domain, sql.js is MIT licensed. API documentationA full API documentation for all the available classes and methods is available. It is generated from comments inside the source code, and is thus always up to date. UsageBy default, sql.js uses wasm, and thus needs to load a const initSqlJs = require('sql.js');
// or if you are in a browser:
// const initSqlJs = window.initSqlJs;
const SQL = await initSqlJs({
// Required to load the wasm binary asynchronously. Of course, you can host it wherever you want
// You can omit locateFile completely when running in node
locateFile: file => `https://sql.js.org/dist/${file}`
});
// Create a database
const db = new SQL.Database();
// NOTE: You can also use new SQL.Database(data) where
// data is an Uint8Array representing an SQLite database file
// Execute a single SQL string that contains multiple statements
let sqlstr = "CREATE TABLE hello (a int, b char); \
INSERT INTO hello VALUES (0, 'hello'); \
INSERT INTO hello VALUES (1, 'world');";
db.run(sqlstr); // Run the query without returning anything
// Prepare an sql statement
const stmt = db.prepare("SELECT * FROM hello WHERE a=:aval AND b=:bval");
// Bind values to the parameters and fetch the results of the query
const result = stmt.getAsObject({':aval' : 1, ':bval' : 'world'});
console.log(result); // Will print {a:1, b:'world'}
// Bind other values
stmt.bind([0, 'hello']);
while (stmt.step()) console.log(stmt.get()); // Will print [0, 'hello']
// free the memory used by the statement
stmt.free();
// You can not use your statement anymore once it has been freed.
// But not freeing your statements causes memory leaks. You don't want that.
const res = db.exec("SELECT * FROM hello");
/*
[
{columns:['a','b'], values:[[0,'hello'],[1,'world']]}
]
*/
// You can also use JavaScript functions inside your SQL code
// Create the js function you need
function add(a, b) {return a+b;}
// Specifies the SQL function's name, the number of it's arguments, and the js function to use
db.create_function("add_js", add);
// Run a query in which the function is used
db.run("INSERT INTO hello VALUES (add_js(7, 3), add_js('Hello ', 'world'));"); // Inserts 10 and 'Hello world'
// Export the database to an Uint8Array containing the SQLite database file
const binaryArray = db.export();DemoThere are a few examples available here. The most full-featured is the Sqlite Interpreter. ExamplesThe test files provide up to date example of the use of the api. Inside the browserExample HTML file:<meta charset="utf8" />
<html>
<script src='/dist/sql-wasm.js'></script>
<script>
config = {
locateFile: filename => `/dist/${filename}`
}
// The `initSqlJs` function is globally provided by all of the main dist files if loaded in the browser.
// We must specify this locateFile function if we are loading a wasm file from anywhere other than the current html page's folder.
initSqlJs(config).then(function(SQL){
//Create the database
const db = new SQL.Database();
// Run a query without reading the results
db.run("CREATE TABLE test (col1, col2);");
// Insert two rows: (1,111) and (2,222)
db.run("INSERT INTO test VALUES (?,?), (?,?)", [1,111,2,222]);
// Prepare a statement
const stmt = db.prepare("SELECT * FROM test WHERE col1 BETWEEN $start AND $end");
stmt.getAsObject({$start:1, $end:1}); // {col1:1, col2:111}
// Bind new values
stmt.bind({$start:1, $end:2});
while(stmt.step()) { //
const row = stmt.getAsObject();
console.log('Here is a row: ' + JSON.stringify(row));
}
});
</script>
<body>
Output is in Javascript console
</body>
</html>Creating a database from a file chosen by the user
dbFileElm.onchange = () => {
const f = dbFileElm.files[0];
const r = new FileReader();
r.onload = function() {
const Uints = new Uint8Array(r.result);
db = new SQL.Database(Uints);
}
r.readAsArrayBuffer(f);
}See : https://sql-js.github.io/sql.js/examples/GUI/gui.js Loading a database from a serverusing fetchconst sqlPromise = initSqlJs({
locateFile: file => `https://path/to/your/dist/folder/dist/${file}`
});
const dataPromise = fetch("/path/to/database.sqlite").then(res => res.arrayBuffer());
const [SQL, buf] = await Promise.all([sqlPromise, dataPromise])
const db = new SQL.Database(new Uint8Array(buf));using XMLHttpRequestconst xhr = new XMLHttpRequest();
// For example: https://github.com/lerocha/chinook-database/raw/master/ChinookDatabase/DataSources/Chinook_Sqlite.sqlite
xhr.open('GET', '/path/to/database.sqlite', true);
xhr.responseType = 'arraybuffer';
xhr.onload = e => {
const uInt8Array = new Uint8Array(xhr.response);
const db = new SQL.Database(uInt8Array);
const contents = db.exec("SELECT * FROM my_table");
// contents is now [{columns:['col1','col2',...], values:[[first row], [second row], ...]}]
};
xhr.send();See: https://github.com/sql-js/sql.js/wiki/Load-a-database-from-the-server Use from node.js
read a database from the disk:const fs = require('fs');
const initSqlJs = require('sql-wasm.js');
const filebuffer = fs.readFileSync('test.sqlite');
initSqlJs().then(function(SQL){
// Load the db
const db = new SQL.Database(filebuffer);
});write a database to the diskYou need to convert the result of const fs = require("fs");
// [...] (create the database)
const data = db.export();
const buffer = Buffer.from(data);
fs.writeFileSync("filename.sqlite", buffer);See : https://github.com/sql-js/sql.js/blob/master/test/test_node_file.js Use as web workerIf you don't want to run CPU-intensive SQL queries in your main application thread, you can use the more limited WebWorker API. You will need to download Example: <script>
const worker = new Worker("/dist/worker.sql-wasm.js");
worker.onmessage = () => {
console.log("Database opened");
worker.onmessage = event => {
console.log(event.data); // The result of the query
};
worker.postMessage({
id: 2,
action: "exec",
sql: "SELECT age,name FROM test WHERE id=$id",
params: { "$id": 1 }
});
};
worker.onerror = e => console.log("Worker error: ", e);
worker.postMessage({
id:1,
action:"open",
buffer:buf, /*Optional. An ArrayBuffer representing an SQLite Database file*/
});
</script>Enabling BigInt supportIf you need <script>
const stmt = db.prepare("SELECT * FROM test");
const config = {useBigInt: true};
/*Pass optional config param to the get function*/
while (stmt.step()) console.log(stmt.get(null, config));
/*OR*/
const result = db.exec("SELECT * FROM test", config);
console.log(results[0].values)
</script>On WebWorker, you can just add <script>
worker.postMessage({
id:1,
action:"exec",
sql: "SELECT * FROM test",
config: {useBigInt: true}, /*Optional param*/
});
</script>See examples/GUI/gui.js for a full working example. Flavors/versions Targets/DownloadsThis library includes both WebAssembly and asm.js versions of Sqlite. (WebAssembly is the newer, preferred way to compile to JavaScript, and has superceded asm.js. It produces smaller, faster code.) Asm.js versions are included for compatibility. Upgrading from 0.x to 1.xVersion 1.0 of sql.js must be loaded asynchronously, whereas asm.js was able to be loaded synchronously. So in the past, you would: <script src='js/sql.js'></script>
<script>
const db = new SQL.Database();
//...
</script>or: const SQL = require('sql.js');
const db = new SQL.Database();
//...Version 1.x: <script src='dist/sql-wasm.js'></script>
<script>
initSqlJs({ locateFile: filename => `/dist/${filename}` }).then(function(SQL){
const db = new SQL.Database();
//...
});
</script>or: const initSqlJs = require('sql-wasm.js');
initSqlJs().then(function(SQL){
const db = new SQL.Database();
//...
});
Downloading/Using:Although asm.js files were distributed as a single Javascript file, WebAssembly libraries are most efficiently distributed as a pair of files, the Versions of sql.js included in the distributed artifactsYou can always find the latest published artifacts on https://github.com/sql-js/sql.js/releases/latest. For each release, you will find a file called
全部评论
专题导读
上一篇：mrdoob/texgen.js: JavaScript Texture Generator发布时间：2022-07-07下一篇：splunk/splunk-sdk-javascript: Splunk Software Development Kit for JavaScript发布时间：2022-07-07热门推荐
热门话题
 阅读排行榜
|
请发表评论