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knadh committed Sep 20, 2011
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<!DOCTYPE html>
<html>
<head>
<title>localStorageDB - A simple database layer for localStorage</title>

<meta name="descript" content="A simple database library for localStorage with support for databases, tables, fields, and insert, select, query, update, and delete operations." />
<meta name="keywords" content="localstorage library, localstorage wrapper, localstorage example, localstorage sql, localstorage linq, web sql, web sql alternative, localstorage database, localstorage tables, localstorage mysql, localstorage query, localstroage structure, localstorage data structure" />

<style>
body {
margin: 0px;
background: #eee;
background-position: top center;
font-family: Arial;
font-size: 12px;
line-height: 22px;
color: #333;
}

#main {
background: #fff;
margin: 0 auto 0 auto;
width: 1000px;
padding: 20px;

box-shadow: 0 0 30px #ddd;
}

.section {
border-bottom: 1px solid #ddd;
padding-bottom: 25px;
margin-bottom: 25px;
}

table {
margin-top: 30px;
border-spacing: 0;
border-color: #ddd;
}
th {
background: #eee;
}
th, td {
padding: 10px;
border-color: #ddd;
}

pre {
font-size: 15px;
padding: 0;
margin: 0;
background: #f6f6f6;
padding: 10px;
overflow: auto;
overflow-Y: hidden;
margin-bottom: 30px;
}

a {
color: #cc0000;
}

h1, h2, h3, h4 {
margin: 0 0 15px 0;
}
</style>
</head>
<body>

<div id="main">
<h1>localStorageDB - a simple, tiny database layer for localStorage</h1>

<p>
Create simple structured databases and tables in localStorage. Insert / update / delete rows.
</p>

<div class="section">

<h3>Creating a database, table, and populating the table</h3>
<pre>
// Initialise. If the database doesn't exist, it is created
var lib = new localStorageDB("library");

// Check if the database was just created. Useful for initial database setup
if( lib.isNew() ) {

// create the "books" table
lib.createTable("books", ["id", "title", "author", "year", "copies"]);

// insert some data
lib.insert("books", {id: "B001", title: "Phantoms in the brain", author: "Ramachandran", year: 1999, copies: 10});
lib.insert("books", {id: "B002", title: "The tell-tale brain", author: "Ramachandran", year: 2011, copies: 10});
lib.insert("books", {id: "B003", title: "Freakonomics", author: "Levitt and Dubner", year: 2005, copies: 10});
lib.insert("books", {id: "B004", title: "Predictably irrational", author: "Ariely", year: 2008, copies: 10});
lib.insert("books", {id: "B005", title: "Tesla: Man out of time", author: "Cheney", year: 2001, copies: 10});
lib.insert("books", {id: "B006", title: "Salmon fishing in the Yemen", author: "Torday", year: 2007, copies: 10});
lib.insert("books", {id: "B007", title: "The user illusion", author: "Norretranders", year: 1999, copies: 10});
lib.insert("books", {id: "B008", title: "Hubble: Window of the universe", author: "Sparrow", year: 2010, copies: 10});

// commit the database to localStorage
// all create/drop/insert/update/delete operations should be committed
lib.commit();
}
</pre>

<h3>Querying</h3>
<pre>
// simple select queries
lib.query("books", {year: 2011});
lib.query("books", {year: 1999, author: "Norretranders"});


// select all books published after 2003
lib.query("books", function(row) { // the callback function is applied to every row in the table
if(row.year > 2003) { // if it returns true, the row is selected
return true;
} else {
return false;
}
});

// select all books by Torday and Sparrow
lib.query("books", function(row) {
if(row.author == "Torday" || row.author == "Sparrow") {
return true;
} else {
return false;
}
});
</pre>

<h3>Example results from a query</h3>
<pre>
// query results are returned as arrays of object literals
// an ID field with the internal auto-incremented id of the row is also included
// thus, ID is a reserved field name

lib.query("books", {author: "ramachandran"});

/* results
[
{
ID: 1,
id: "B001",
title: "Phantoms in the brain",
author: "Ramachandran",
year: 1999,
copies: 10
},
{
ID: 2,
id: "B002",
title: "The tell-tale brain",
author: "Ramachandran",
year: 2011,
copies: 10
}
]
*/
</pre>


<h3>Updating</h3>
<pre>
// change the title of books published in 1999 to "Unknown"
lib.query("books", {year: 1999}, function(row) {
row.title = "Unknown";

// the update callback function returns to the modified record
return row;
});

// add +5 copies to all books published after 2003
lib.query("books",
function(row) { // select condition callback
if(row.year > 2003) {
return true;
} else {
return false;
}
},
function(row) { // update function
row.year+=5;
return row;
}
);
</pre>

<h3>Deleting</h3>
<pre>
// delete all books published in 1999
lib.delete("books", {year: 1999});

// delete all books published before 2005
lib.delete("books", function(row) {
if(row.year < 2005) {
return true;
} else {
return false;
}
});

lib.commit(); // commit the deletions to localStorage
</pre>

</div>

<table border="1">
<thead>
<tr>
<th>Method</th/>
<th>Arguments</th/>
<th>Description</th>
</tr>
</thead>
<tbody>
<tr>
<td>localStorageDB()</td>
<td>database_name</td>
<td>Constructor</td>
</tr>
<tr>
<td>isNew()</td>
<td></td>
<td>Returns true if a database was created at the time of initialisation with the constructor</td>
</tr>
<tr>
<td>drop()</td>
<td></td>
<td>Deletes a database, and purges it from localStorage</td>
</tr>
<tr>
<td>tableCount()</td>
<td></td>
<td>Returns the number of tables in a database</td>
</tr>
<tr>
<td>commit()</td>
<td></td>
<td>Commits the database to localStorage</td>
</tr>


<tr>
<td>tableExists()</td>
<td>table_name</td>
<td>Checks whether a table exists in the database</td>
</tr>
<tr>
<td>createTable()</td>
<td>table_name, fields</td>
<td>Create a table&mdash;fields is an array of string fieldnames. 'ID' is a reserved fieldname.</td>
</tr>
<tr>
<td>dropTable()</td>
<td>table_name</td>
<td>Delete a table from the database</td>
</tr>
<tr>
<td>truncate()</td>
<td>table_name</td>
<td>Empties all records in a table</td>
</tr>
<tr>
<td>rowCount()</td>
<td>table_name</td>
<td>Returns the number of rows in a table</td>
</tr>


<tr>
<td>insert()</td>
<td>table_name, data</td>
<td>Inserts a row into a table. data is an object literal with field-values. Every row is assigned an auto-incremented numerical id automatically</td>
</tr>
<tr>
<td>query</td>
<td>table_name, query</td>
<td>Returns an array of rows (object literals) from a table matching the query&mdash;query is either an object literal or a function. Every returned row will have it's internal auto-incremented id assigned to the variable ID</td>
</tr>
<tr>
<td>update()</td>
<td>table_name, query, update_function</td>
<td>Updates an existing record. query is an object literal or a function. update_function is a function that returns an object literal with the updated values</td>
</tr>
<tr>
<td>delete()</td>
<td>table_name, query</td>
<td>Deletes rows from a table matching query&mdash;query is either an object literal or a function</td>
</tr>
</tbody>
</table>

<p>&mdash; <a href="http://kailashnadh.name">Kailash Nadh</a></p>

</div><!-- main //-->

</body>
</html>
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