1. Phonegap Bridge – File System CIS 136 Building Mobile Apps 1

2. Storage Options Storage API 2

3. Methods 3 1. First instruction will be to openDatabase() –  Creates a new SQLLite database or opens one that has already been created  database is in persistent storage  This method returns a database object that allows manipulation of the data var appDB = window.openDatabase(“myDB”,”1.0”,”notes”, 1024*1024); 2. Next instruction will be the transaction()–  executes SQL statements using executeSql() method  The first executeSql() method is to create/open a table appDB.transaction(txnSQLFunc,onTxnError,onTxnSuccess); function txnSQLFunc() { }

4. Process so far… 4 var appDB = window.openDatabase(“myDB”,”1.0”,”notes”, 1024*1024); appDB.transaction(CreateTable,onTxError,onTxSuccess); function CreateTable(tx) { var sqlString = ‘CREATE TABLE IF NOT EXISTS STUDENTS (StudentID TEXT PRIMARY KEY NOT NULL, FirstName TEXT, LastName TEXT, Email TEXT)’; tx.executeSql(sqlString, [], onSqlSuccess(), onSqlError(); } function onTxError(tx,err) { console.log(“transaction failed: Code: “ + err.code); } fuction onTxSuccess() { console.log(“Transaction successful”); }

5. Understanding executeSql() 5  Executes sql statements  Four parameters  SQL Statement – to execute against the database object the transaction isassociated with  Value – array of values passed to SQL statement  Success function – Function that will execute if the SQL statement is sucessfully processed  Error function –function that will execute if the SQL statement fails  The success function is passed two parameters:  a transaction object (which is used to execute additional SQL statements against the table)  A results object which contains the results of the SQL operation  The results object exposes the following properties:  insertID:If the SQL statement was to insert a record, the ROW ID  rowAffected: If the SQL statement selected, inserted, updated, or deleted records, the number of records affected  Rows: An object containing the records returned by the SQ statement

6. example sqlSuccess function 6 function onSqlSuccess(tx,res) { If (res) // make sure a results object was returned { console.log(“Insert ID: “ + res.insertID); console.log(“Rows affected: “ + res.rowAffected; if (res.rows) // if records were returned { var numRecs = res.rows.length; if numRecs > 0 { for (var i=0; i< numrecs; i++) { // do something with each record }

7. Select Statement 7  Retrieves records from a table  Syntax: SELECT * FROM table_name;  Syntax for sorting records SELECT * FROM table_name ORDER BY column_name ASC|DESC, column_name ASC|DESC ;  Syntax for filtering records SELECT * FROM table_name WHERE column_name operator value [AND column_name operator value] [OR column_name operator value];

8. Insert Into Statement 8  Adds a record to the table  Syntax INSERT INTO table_name (column1,column2,column3,...) VALUES (value1,value2,value3,...);  Example function insertRecord(tx) { var str= “INSERT INTO Customers (CustomerName,Country) VALUES ('Tom Smith', 'Norway')”; tx.executeSql(str,[],onInsertSuccess,onInsertError); }

9. Insert Into Statement 9  Example 2 function insertRecord(tx) { var strName = document.getElementById(“custName”).value; var strCtry = document.getElementById(“custCtry”).value; var str= “INSERT INTO Customers (CustomerName,Country) VALUES (?,?)”; tx.executeSql(str,[strName,strCtry],onInsertSuccess,onInse rtError); }

10. Update Statement 10  Updates a record that is in the table  Syntax UPDATE table_name SET column1=value1,column2=value2,... [WHERE some_column=some_value]; Example function updateRecord(tx) { var strName = document.getElementById(“custName”).value; var strCtry = document.getElementById(“custCtry”).value; var str= “UPDATE Customers SET CustomerName = strName,Country=strCtry) WHERE Country=‘Norway’ tx.executeSql(str,[],onUpdateSuccess,onUpdateError); }

11. Delete Statement 11  Removes a record from the table  Syntax DELETE FROM table_name [WHERE some_column=some_value]; Example function deleteRecord(tx) { var str= “DELETE FROM Customers WHERE Country=‘Norway’; tx.executeSql(str,[],onDeleteSuccess,onDeleteError); }