The source code

    // Asbtract base class for SqlDB classes
    Ext.data.SqlDB = function(config){
    	Ext.apply(this, config);
    	Ext.data.SqlDB.superclass.constructor.call(this);

    	this.addEvents({
    		open : true,
    		close: true
    	});
    };

    Ext.extend(Ext.data.SqlDB, Ext.util.Observable, {
    	maxResults: 10000,
    	openState : false,

        // abstract methods
        open : function(file, cb, scope){
    	},

    	close : function(){
    	},

        exec : function(sql, cb, scope){
    	},

    	execBy : function(sql, args, cb, scope){
    	},

    	query : function(sql, cb, scope){
    	},

    	queryBy : function(sql, args, cb, scope){
    	},

        // protected/inherited method
        isOpen : function(){
    		return this.openState;
    	},

    	getTable : function(name, keyName){
    		return new Ext.data.SqlDB.Table(this, name, keyName);
    	},

    	createTable : function(o){
    		var tableName = o.name;
    		var keyName = o.key;
    		var fs = o.fields;
    		var cb = o.callback;
    		var scope = o.scope;
    		if(!(fs instanceof Array)){ // Ext fields collection
    			fs = fs.items;
    		}
    		var buf = [];
    		for(var i = 0, len = fs.length; i < len; i++){
    			var f = fs[i], s = f.name;
    			switch(f.type){
    	            case "int":
    	            case "bool":
    	            case "boolean":
    	                s += ' INTEGER';
    	                break;
    	            case "float":
    	                s += ' REAL';
    	                break;
    	            default:
    	            	s += ' TEXT';
    	        }
    	        if(f.allowNull === false || f.name == keyName){
    	        	s += ' NOT NULL';
    	        }
    	        if(f.name == keyName){
    	        	s += ' PRIMARY KEY';
    	        }
    	        if(f.unique === true){
    	        	s += ' UNIQUE';
    	        }

    	        buf[buf.length] = s;
    	    }
    	    var sql = ['CREATE TABLE IF NOT EXISTS ', tableName, ' (', buf.join(','), ')'].join('');
            this.exec(sql, cb, scope);
    	}
    });

    Ext.data.SqlDB.getInstance = function(db, config){
        if(window.htmlControl){ // air
            return new Ext.data.AirDB(config);
        } else { // gears
            return new Ext.data.GearsDB(config);
        }
    };

    Ext.data.SqlDB.Table = function(conn, name, keyName){
    	this.conn = conn;
    	this.name = name;
    	this.keyName = keyName;
    };

    Ext.data.SqlDB.Table.prototype = {
    	update : function(o, cb, scope){
    		var clause = this.keyName + " = :" + this.keyName;
    		this.updateBy(o, clause, {}, cb, scope);
    	},

    	updateBy : function(o, clause, args, cb, scope){
    		var sql = "UPDATE " + this.name + " set ";
    		var fs = [], a = [];
    		for(var key in o){
    			if(o.hasOwnProperty(key)){
    				fs[fs.length] = key + ' = ?';
    				a[a.length] = o[key];
    			}
    		}
    		for(var key in args){
    			if(args.hasOwnProperty(key)){
    				a[a.length] = args[key];
    			}
    		}
    		sql = [sql, fs.join(','), ' WHERE ', clause].join('');
    		this.conn.execBy(sql, a, cb, scope);
    	},

    	insert : function(o, cb, scope){
    		var sql = "INSERT into " + this.name + " ";
    		var fs = [], vs = [], a = [];
    		for(var key in o){
    			if(o.hasOwnProperty(key)){
    				fs[fs.length] = key;
    				vs[vs.length] = '?';
    				a[a.length] = o[key];
    			}
    		}
    		sql = [sql, '(', fs.join(','), ') VALUES (', vs.join(','), ')'].join('');
            this.conn.execBy(sql, a, cb, scope);
        },

    	select : function(clause, cb, scope){
    		this.selectBy(clause, null, cb, scope);
    	},

    	selectBy : function(clause, args, cb, scope){
    		var sql = "select * from " + this.name;
    		if(clause){
    			sql += ' ' + clause;
    		}
    		args = args || {};
    		this.conn.queryBy(sql, args, cb, scope);
    	},

    	remove : function(clause, cb, scope){
    		this.deleteBy(clause, null, cb, scope);
    	},

    	removeBy : function(clause, args, cb, scope){
    		var sql = "delete from " + this.name;
    		if(clause){
    			sql += ' where ' + clause;
    		}
    		args = args || {};
    		this.conn.execBy(sql, args, cb, scope);
    	}
    };

    Ext.data.SqlDB.Proxy = function(conn, table, keyName, store){
        Ext.data.SqlDB.Proxy.superclass.constructor.call(this);
        this.conn = conn;
        this.table = this.conn.getTable(table, keyName);
        this.store = store;

        this.store.on('add', this.onAdd, this);
        this.store.on('update', this.onUpdate, this);
        this.store.on('remove', this.onRemove, this);
    };

    Ext.extend(Ext.data.SqlDB.Proxy, Ext.data.DataProxy, {
        load : function(params, reader, callback, scope, arg){
        	if(!this.conn.isOpen()){ // assume that the connection is in the process of opening
        		this.conn.on('open', function(){
        			this.load(params, reader, callback, scope, arg);
        		}, this, {single:true});
        		return;
        	};
        	if(this.fireEvent("beforeload", this, params, reader, callback, scope, arg) !== false){
    			var clause = params.where || '';
    			var args = params.args || [];
    			var group = params.groupBy;
    			var sort = params.sort;
    			var dir = params.dir;

    			if(group || sort){
    				clause += ' ORDER BY ';
    				if(group && group != sort){
    					clause += group + ' ASC, ';
    				}
    				clause += sort + ' ' + (dir || 'ASC');
    			}

    			this.table.selectBy(clause, args,
    					this.onLoad.createDelegate(this, [{callback:callback, scope:scope, arg:arg, reader: reader}], 0));
            }else{
                callback.call(scope||this, null, arg, false);
            }
        },

        onLoad : function(trans, rs, e, stmt){
            if(rs === false){
        		this.fireEvent("loadexception", this, null, trans.arg, e);
                trans.callback.call(trans.scope||window, null, trans.arg, false);
                return;
        	}
        	var result = trans.reader.readRecords(rs);
            this.fireEvent("load", this, rs, trans.arg);
            trans.callback.call(trans.scope||window, result, trans.arg, true);
        },

        processData : function(o){
        	var fs = this.store.fields;
        	var r = {};
        	for(var key in o){
        		var f = fs.key(key), v = o[key];
    			if(f){
    				if(f.type == 'date'){
    					r[key] = v ? v.format('Y-m-d H:i:s') : '';
    				}else if(f.type == 'boolean'){
    					r[key] = v ? 1 : 0;
    				}else{
    					r[key] = v;
    				}
    			}
    		}
    		return r;
        },

        onUpdate : function(ds, record){
        	var changes = record.getChanges();
        	var kn = this.table.keyName;
        	this.table.updateBy(this.processData(changes), kn + ' = ?', [record.data[kn]]);
        	record.commit(true);
        },

        onAdd : function(ds, records, index){
        	for(var i = 0, len = records.length; i < len; i++){
            	this.table.insert(this.processData(records[i].data));
        	}
        },

        onRemove : function(ds, record, index){
            var kn = this.table.keyName;
        	this.table.removeBy(kn + ' = ?', [record.data[kn]]);
        }
    });