PhoneGap storage, Passing Variables to db.transaction, SQL Lite

Question

I'm working with the PhoneGap Open Database API. According to this documentation values should be inserted into an existing table using the follow code

function populateDB(tx) {
     tx.executeSql('DROP TABLE IF EXISTS DEMO');
     tx.executeSql('CREATE TABLE IF NOT EXISTS DEMO (id unique, data)');
     tx.executeSql('INSERT INTO DEMO (id, data) VALUES (1, "First row")');
     tx.executeSql('INSERT INTO DEMO (id, data) VALUES (2, "Second row")');
}

function errorCB(tx, err) {
    alert("Error processing SQL: "+err);
}

function successCB() {
    alert("success!");
}

  var db = window.openDatabase("Database", "1.0", "PhoneGap Demo", 200000);
  db.transaction(populateDB, errorCB, successCB);

This works fine but now I'm trying to pass a variable to the populateDB function. When I try the code below

  var db = window.openDatabase("Database", "1.0", "PhoneGap Demo", 200000);
  db.transaction(populateDB("test variable"), errorCB, successCB);

the "test variable" string goes through but tx is undefined. Does anyone know how to do this?

Answer 1

I think the only way you could do this would be write a function that returns a function that makes use of the passed in value. Something along the lines of :

function makeMyDB(x) {
    var result = function() {
     tx.executeSql('DROP TABLE IF EXISTS DEMO');
     tx.executeSql('CREATE TABLE IF NOT EXISTS DEMO (id unique, data)');
     tx.executeSql('INSERT INTO DEMO (id, data) VALUES (1, "'+x+'")');
    }
   return result;
} 

You could then try passing makeMyDB(x) as the first argument.

Answer 2

If anyone else is still looking for a solution to this problem, I have a little solution for passing variable without changing or loosing the tx, you just have to write this for example:

var myvar = 1; //an int or something else
db.transaction(function(tx){
    selectQueryDB(tx,myvar);
    },errorCB);



function selectQueryDB(tx,myvar){
    tx.executeSql('SELECT * FROM mytable WHERE myparam='+myvar, [], renderList, errorCB);

}

function errorCB(err){
    alert("Error Processing SQL: "+ err.code );
}
function renderList(tx,results){
enter code here
}