Using Database

HTML5 Web SQL Database connects to the device database. This section describes Web SQL Database usage.

Web SQL Database

You need to create a new Database object before accessing to it. window.openDatabase function creates a new SQLite database.

var db = window.openDatabase(database_name, database_version, database_displayname, database_size);

Creating a Database (SQLite)

<!DOCTYPE html>
<html>
  <head>
    <meta name="viewport" content="width=device-width, user-scalable=no">
    <script type="text/javascript" charset="utf-8" src="components/loader.js"></script>
    <script type="text/javascript" charset="utf-8">
      document.addEventListener("deviceready", onDeviceReady, false);
      function onDeviceReady() {
          var db = window.openDatabase("database", "1.0", "testdatabase", 1000000);
      }
    </script>
  </head>
  <body>
  <pre>Web SQL Database</pre>
  </body>
</html>

openDatabase Arguments

Arguments

Description

Value

database_name

Database name

String

database_version

Database version

String

database_displayname

Database display name

String

database_size

Database size (in bytes)

Integer number

Database Object Methods

Function

Description

transaction

Starts transaction.

changeVersion

Checks version and updates schema if necessary.

executesql function in SQLTransaction object is an actual method to execute SQL. You need to execute transaction function in Database object to get SQLTransaction object. When executing executeSql function in SQLTransaction object, the callback function is executed and SQLResultSet object is passed to it.

SQLResultSet Object Properties

Property

Description

insertId

Returns row number when INSERT statement is successful.

rowsAffected

Returns affected rows after sql execution.

rows

Returns ResultSetRowList object. It represents the results of the sql execution.

Executing SQL (SQLite)

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, user-scalable=no">
    <script type="text/javascript" charset="utf-8" src="components/loader.js"></script>
    <script type="text/javascript" charset="utf-8">

    document.addEventListener("deviceready", onDeviceReady, false);

    function onDeviceReady() {

        window.alert("Create a database and display the content");

    }


    function executeQuery(tx) {
        tx.executeSql('DROP TABLE IF EXISTS TestTable');
        tx.executeSql('CREATE TABLE IF NOT EXISTS TestTable (id unique, data)');
        tx.executeSql('INSERT INTO TestTable (id, data) VALUES (1, "あいうえお")');
        tx.executeSql('INSERT INTO TestTable (id, data) VALUES (2, "かきくけこ")');
        tx.executeSql('INSERT INTO TestTable (id, data) VALUES (3, "さしすせそ")');
        tx.executeSql('INSERT INTO TestTable (id, data) VALUES (4, "たちつてと")');        
        tx.executeSql('INSERT INTO TestTable (id, data) VALUES (5, "なにぬねの")');
        tx.executeSql('INSERT INTO TestTable (id, data) VALUES (6, "はひふへほ")');
        tx.executeSql('INSERT INTO TestTable (id, data) VALUES (7, "まみむめも")');

    }

    function queryDB(tx) {
        tx.executeSql('SELECT * FROM TestTable', [], querySuccess, errorCB);
    }

    function querySuccess(tx, results) {
        var len = results.rows.length;
        window.alert("There are " + len + " rows of records in the database.");
        for (var i=0; i<len; i++){
            document.writeln("row = " + i + " ID = " + results.rows.item(i).id + " Data = " + results.rows.item(i).data+"<br/>");
        }        
    }

    //Callback function when the transaction is failed.
    function errorCB(err) {
        console.log("Error occured while executing SQL: "+err.code);
    }

    // Callback function when the transaction is success.
    function successCB() {
        var db = window.openDatabase("Database", "1.0", "TestDatabase", 200000);
        db.transaction(queryDB, errorCB);
    }

    function createDB(){
        var db = window.openDatabase("Database", "1.0", "TestDatabase", 200000);
        db.transaction(executeQuery, errorCB, successCB);

    }      

    </script>
  </head>
  <body>
  <h1>Execute the SQL</h1>
  <input type="button" value="Execute SQL transactions" onclick="createDB()">
  </body>
</html>
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