// Escape a SQL string for embedding as a Python string literal.
//// Placeholder rewriting (e.g. $1 → %(name)s for psycopg) lives per-driver
// because only some drivers need it. This helper operates on already-
// rewritten SQL.
pubfnescape_sql(s:&str)-> String{
s.replace('\\',"\\\\").replace('"',"\\\"").replace('\n',"\\n").replace('\r',"\\r").replace('\t',"\\t")}