Working with WebSQL. How to add new column to existing table?

Question

I have simple WebSQL database with 1 table and 3 columns. I would like to add one more column, but I can't do it if the database already exist. It's only possible after I have cleaned it in the cache, but then I'm loosing all the data.

How can I add new column to a table without removing the database?

// database creating
MYDB.init.open = function(){
       MYDB.init.db = openDatabase("MYDB","1.0"," super-data-base",1024*1024*5);
}


//table creating    
MYDB.init.createTable = function(){
           var database = MYDB.init.db;
           database.transaction(function(tx){
                  tx.executeSql("CREATE TABLE IF NOT EXISTS mytable (ID INTEGER PRIMARY KEY ASC,item TEXT,description TEXT)", []);
           });
    }

//
//a lot of code for adding datas and reading datas
//

//database updating that does not work
MYDB.init.updateTable = function(){
       var database = MYDB.init.db;
       database.transaction(function(tx){
              tx.executeSql("ALTER TABLE mytable ADD time VARCHAR NOT NULL BEFORE description");
       });
}

All other UPDATE functions are working well.

Answer 1

The correct Request is:

ALTER TABLE mytable ADD time VARCHAR NOT NULL DEFAULT '' 

(without BEFORE, AFTER, because WebSQL does't support this syntax)