$re = '/[{(, ](?<Dimensions>[a-z0-9A-Z\[\.\]+[\-\ \_]*)[\.&\[]/m';
$str = 'SELECT { [Measures].[IMS Org Count] } ON COLUMNS, NONEMPTY ( { [End User].[End User ID].[End User ID].MEMBERS * [End User].[End User Name].[End User Name].MEMBERS * [Product].[PMBU Short Desc].[PMBU Short Desc].MEMBERS * [Product].[PMBU Medium Desc].[PMBU Medium Desc].MEMBERS * [IMS Org].[Unique Id].[Unique Id].MEMBERS * [IMS Org].[IMS Org Id].[IMS Org Id].MEMBERS * [IMS Org].[MC Org Name].[MC Org Name].MEMBERS * [Is Active Account].[Is Active Account].[Is Active Account].MEMBERS* [Billing End User].[End User ID].[End User ID].MEMBERS } , [Measures].[IMS Org Count] ) ON ROWS FROM ( SELECT CASE \'1\' WHEN "5" THEN [Account Manager].[AM Org Lead Ldap].[AM Org Lead Ldap].[xxxx] WHEN "4" THEN [Account Manager].[Regional Manager Ldap].[Regional Manager Ldap].[xxx] WHEN "3" THEN [Account Manager].[AM Manager Ldap].[AM Manager Ldap].[xxx] WHEN "2" THEN [Account Manager].[AM Lead Ldap].[AM Lead Ldap].[xxx] WHEN "1" THEN [Account Manager].[AM Ldap].[AM Ldap].[xxxx] END ON 0 FROM XX )';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
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 PHP, please visit: http://php.net/manual/en/ref.pcre.php