func RegisterStmt(sql string) int {
	code := len(stmts)
	stmts[code] = sql
	return code
}
func RegisterStmt(sql string) int {
	code := len(stmts)
	stmts[code] = sql
	return code
}
// RegisterStmt register a SQL statement.
//
// Registered statements will be prepared upfront and re-used, to speed up
// execution.
//
// Return a unique registration code.