Fix：修复 SQL Server datetime 查询和导出精度

crates/dbx-core/src/db/sqlserver.rs

@@ -598,7 +598,11 @@ fn sqlserver_cell_to_json(cell: &ColumnData<'static>) -> serde_json::Value {
         return serde_json::Value::String(v.to_string());
     }
     if let Ok(Some(v)) = <chrono::NaiveDateTime as FromSql>::from_sql(cell) {
-        return serde_json::Value::String(v.to_string());
+        let value = match cell {
+            ColumnData::DateTime(_) => crate::sqlserver_temporal::format_sqlserver_datetime_display(&v),
+            _ => v.to_string(),
+        };
+        return serde_json::Value::String(value);
     }
     if let Ok(Some(v)) = <chrono::NaiveDate as FromSql>::from_sql(cell) {
         return serde_json::Value::String(v.to_string());
@@ -2125,6 +2129,13 @@ mod tests {
         assert_eq!(sqlserver_cell_to_json(&cell), serde_json::json!("2026-05-13 09:08:07.123"));
     }
 
+    #[test]
+    fn sqlserver_datetime_cells_display_millisecond_precision() {
+        let cell = ColumnData::DateTime(Some(tiberius::time::DateTime::new(46_200, 11_001_869)));
+
+        assert_eq!(sqlserver_cell_to_json(&cell), serde_json::json!("2026-06-29 10:11:12.897"));
+    }
+
     #[test]
     fn sqlserver_binary_cells_are_json_hex_strings() {
         let cell =