#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = ".*?(?<=(?:FROM|JOIN))\s*(.*?)\s*(?=(?:ON|JOIN|WHERE|LIMIT|GROUP|ORDER|\(|;))"
Local $sString = "SELECT * FROM (SELECT * FROM table1, table2 WHERE bla,bla GROUP BY bla ORDER bla LIMIT bla) tableTmp UNION SELECT * FROM table3,table4 WHERE bla;"
Local $sSubst = "\1"
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm