The source code

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

    	if (readonly !== true) {
    		this.store.on('add', this.onAdd, this);
    		this.store.on('update', this.onUpdate, this);
    		this.store.on('remove', this.onRemove, this);
    	}
    };

    Ext.sql.Proxy.DATE_FORMAT = 'Y-m-d H:i:s';

    Ext.extend(Ext.sql.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');
    			}

    			var rs = this.table.selectBy(clause, args);
    			this.onLoad({callback:callback, scope:scope, arg:arg, reader: reader}, rs);
            }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(Ext.sql.Proxy.DATE_FORMAT,10) : '';
    				}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]]);
        }
    });