I recently needed to parse a line of text which represents a stored procedure call to a database.
The format is
databaseName#storedProcedureName @parameterName=parameterValue

in .Net I used the named groups in my regular expression to get the parts:

^(?<database>[a-z]+)#(?<sproc>[a-z_0-9]+)( (?<parametername>@[a-z_0-9]+)=(?<parametervalue>[a-z_0-9']+))?

Database and stored procedure name are mandatory, then optionally separated by a space a single parameter.

   RegexOptions options = RegexOptions.IgnoreCase;
   Regex regex = new Regex(@"^(?[a-z]+)#(?[a-z_0-9]+)( (?@[a-z_0-9]+)=(?[a-z_0-9']+))?", options);

   Match match = regex.Match(sprocCall);

   if (match.Groups.Count == 6)
   {
       // we always expect six groups
       // if not the string format was not correct
       string database = match.Groups["database"].Value;
       string sprocName = match.Groups["sproc"].Value;
       string parameterName = match.Groups["parametername"].Value.Trim();
       string parameterValue = match.Groups["parametervalue"].Value.Trim();
       // use the components to make a database call
	}