Here is the simplified example for web sql db create, read, update and delete operations:
<!DOCTYPE HTML>
<html>
<head>
<script type="text/javascript">
var db;
function createDatabase(dbName){
db = openDatabase(dbName, '1.0', 'Test DB', 2 * 1024 * 1024);
}
function createTable(tableName, arrFields){
db.transaction(function (tx) {
var fields = "";
for(f=0;f<arrFields.length;f++){
fields += arrFields[f] + ',';
}
fields = fields.substring(0, fields.length-1);
tx.executeSql('CREATE TABLE IF NOT EXISTS '+ tableName + ' (' + fields + ')');
});
}
function insertRecord(query){
db.transaction(function (tx) {
tx.executeSql(query);
});
}
function selectRecord(query, callBack){
var empArr = new Array();
db.transaction(function (tx) {
tx.executeSql(query, [], function (tx, results) {
var len = results.rows.length;
// Create the object of emp
for(i=0;i<len;i++){
var emp = {
id:results.rows.item(i).id,
name:results.rows.item(i).name,
salary:results.rows.item(i).salary
};
// Add objects to array
empArr[i] = emp;
}
callBack(empArr); // This is the callback
});
});
}
createDatabase('db_emp');
createTable('emp', ["id", "name", "salary"]);
insertRecord('INSERT INTO emp (id, name, salary) VALUES (1, "Rahul", 5000)');
// We are using callback in this method
selectRecord('select * from emp', function (results){
console.log(results);
});
</script>
</head>
<body>
</body>
</html>
<!DOCTYPE HTML>
<html>
<head>
<script type="text/javascript">
var db;
function createDatabase(dbName){
db = openDatabase(dbName, '1.0', 'Test DB', 2 * 1024 * 1024);
}
function createTable(tableName, arrFields){
db.transaction(function (tx) {
var fields = "";
for(f=0;f<arrFields.length;f++){
fields += arrFields[f] + ',';
}
fields = fields.substring(0, fields.length-1);
tx.executeSql('CREATE TABLE IF NOT EXISTS '+ tableName + ' (' + fields + ')');
});
}
function insertRecord(query){
db.transaction(function (tx) {
tx.executeSql(query);
});
}
function selectRecord(query, callBack){
var empArr = new Array();
db.transaction(function (tx) {
tx.executeSql(query, [], function (tx, results) {
var len = results.rows.length;
// Create the object of emp
for(i=0;i<len;i++){
var emp = {
id:results.rows.item(i).id,
name:results.rows.item(i).name,
salary:results.rows.item(i).salary
};
// Add objects to array
empArr[i] = emp;
}
callBack(empArr); // This is the callback
});
});
}
createDatabase('db_emp');
createTable('emp', ["id", "name", "salary"]);
insertRecord('INSERT INTO emp (id, name, salary) VALUES (1, "Rahul", 5000)');
// We are using callback in this method
selectRecord('select * from emp', function (results){
console.log(results);
});
</script>
</head>
<body>
</body>
</html>