You have found one of the current limitations of ESS - external fields from the external source cannot be indexed and therefore cannot be used with features such as value lists based on an ESS field (index) and auto-complete (type ahead) in an ESS field.
Nothing you can do about it. Sorry :(
I've tryed to bypass this problem with a script that import in filemaker local tables the data in the mysql tables but I must go through a tab file. I mean that the script export the data of mysql tables in that file and then import them on local table.
Could you suggest me an easier method??
This limitation affect also the arranging of the field? example: arranging by name, date, etc..??
If you want the data out of SQL and into FileMaker Pro, you'll need some kind of export routine from SQL and then import through a tab-delimited file. There is no direct way. Once the data is in FileMaker Pro, you can index it, sort it, use it in value lists, etc.
If you are going to be doing this on an ongoing basis, then you may want to develop a script to automate the importing of the file.
You can import from the SQL table as an ODBC source, thereby skipping the need for a SQL export.