Populating New Field In Mobile Lookup

​@Pinmaya Kumar Singh 

Looks like a bit of syntax issues.

• getControlValue expects different inputs.
  object getControlValue(string tableName, string columnName)
• getUserInfo - This function is used to return information about the currently logged‐in user.
  Dont think this is your intention.
• Do you have the part synced into mobile? 
• setControlValue expects different inputs.
  bool setControlValue(string tableName, string columnName, object value)

This is my best guess:

var partid = getcontrolvalue('part','external_ref');
var rexid = getdbvalue(stringformat("select external_ref from part where part_id='{0}'", partid));
setcontrolvalue('part','external_ref',rexid);

Cheers!