need to escape \ still?

src/sql/ser.rs

@@ -321,7 +321,14 @@ impl<'a, W: Write> Serializer for ParamSerializer<'a, W> {
     fn serialize_str(self, value: &str) -> Result {
         // ClickHouse expects strings in params to be unquoted until inside a nested type
         // nested types go through serialize_seq which'll quote strings
-        self.writer.write_str(value)?;
+        let mut rest = value;
+        while let Some(nextidx) = rest.find('\\') {
+            let (before, after) = rest.split_at(nextidx + 1);
+            rest = after;
+            self.writer.write_str(before)?;
+            self.writer.write_char('\\')?;
+        }
+        self.writer.write_str(rest)?;
         Ok(())
     }
 

tests/it/query.rs

@@ -111,12 +111,12 @@ async fn server_side_param() {
 
     let result = client
         .query("SELECT {val1: String} AS result")
-        .with_param("val1", "\x01\x02\x03\\\"\'")
+        .with_param("val1", "\x01\x02\x03\\ \"\'")
         .expect("failed to bind weird string")
         .fetch_one::<String>()
         .await
         .expect("failed to fetch string");
-    assert_eq!(result, "\x01\x02\x03\\\"\'");
+    assert_eq!(result, "\x01\x02\x03\\ \"\'");
 
     let result = client
         .query("SELECT {val1: Array(String)} AS result")