chore: Address CR comments

src/common/error/src/ext.rs

@@ -20,7 +20,7 @@ macro_rules! define_opaque_error {
         /// An error behaves like `Box<dyn Error>`.
         ///
         /// Define this error as a new type instead of using `Box<dyn Error>` directly so we can implement
-        /// more method or trait for it.
+        /// more methods or traits for it.
         pub struct $Error {
             inner: Box<dyn $crate::ext::ErrorExt + Send + Sync>,
         }

src/common/error/src/mock.rs

@@ -33,7 +33,7 @@ impl MockError {
 
 impl fmt::Display for MockError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{:?}", self.code)
+        write!(f, "{}", self.code)
     }
 }
 

src/common/error/src/status_code.rs

@@ -1,3 +1,5 @@
+use std::fmt;
+
 /// Common status code for public API.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub enum StatusCode {
@@ -6,6 +8,8 @@ pub enum StatusCode {
     Unknown,
     /// Unsupported operation.
     Unsupported,
+    /// Unexpected error, maybe there is a BUG.
+    Unexpected,
     /// Internal server error.
     Internal,
     // ====== End of common status code ================
@@ -15,8 +19,38 @@ pub enum StatusCode {
     InvalidSyntax,
     // ====== End of SQL related status code ===========
 
+    // ====== Begin of query related status code =======
+    /// Fail to create a plan for the query.
+    PlanQuery,
+    /// The query engine fail to execute query.
+    EngineExecuteQuery,
+    // ====== End of query related status code =========
+
     // ====== Begin of catalog related status code =====
     /// Table already exists.
     TableAlreadyExists,
     // ====== End of catalog related status code =======
 }
+
+impl fmt::Display for StatusCode {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // The current debug format is suitable to display.
+        write!(f, "{:?}", self)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn assert_status_code_display(code: StatusCode, msg: &str) {
+        let code_msg = format!("{}", code);
+        assert_eq!(msg, code_msg);
+    }
+
+    #[test]
+    fn test_display_status_code() {
+        assert_status_code_display(StatusCode::Unknown, "Unknown");
+        assert_status_code_display(StatusCode::TableAlreadyExists, "TableAlreadyExists");
+    }
+}