hi, thanks for your answers. the error was caused by another query. i did not think twice. my strings came from another source, already single-quoted, so " .. where id=''uuidstring'';" was the actual mistake. if you want to say that 'a 'b' c' does not work. this is actually "a 'b' c". the outer single quotes from my simple printf-debugging. i know about "\'" and '\"'. but if you think of something different, i would like to know.