diff --git a/examples/basic/src/main.rs b/examples/basic/src/main.rs
index 58c09db0..7d0a2ca7 100644
--- a/examples/basic/src/main.rs
+++ b/examples/basic/src/main.rs
@@ -23,7 +23,7 @@ use select::*;
 
 #[async_std::main]
 async fn main() {
-    let db = Database::connect("sql://sea:sea@localhost/bakery")
+    let db = Database::connect("mysql://sea:sea@localhost/test")
         .await
         .unwrap();
 
@@ -32,8 +32,4 @@ async fn main() {
     println!("===== =====\n");
 
     all_about_select(&db).await.unwrap();
-
-    println!("===== =====\n");
-
-    all_about_operation(&db).await.unwrap();
 }
diff --git a/examples/basic/src/select.rs b/examples/basic/src/select.rs
index bb1354fb..7d051144 100644
--- a/examples/basic/src/select.rs
+++ b/examples/basic/src/select.rs
@@ -2,46 +2,8 @@ use super::*;
 use sea_orm::{entity::*, error::*, query::*, DbConn, FromQueryResult};
 
 pub async fn all_about_select(db: &DbConn) -> Result<(), DbErr> {
-    find_all(db).await?;
-
-    println!("===== =====\n");
-
-    find_one(db).await?;
-
-    println!("===== =====\n");
-
-    find_one_to_one(db).await?;
-
-    println!("===== =====\n");
-
     find_one_to_many(db).await?;
 
-    println!("===== =====\n");
-
-    count_fruits_by_cake(db).await?;
-
-    println!("===== =====\n");
-
-    find_many_to_many(db).await?;
-
-    if false {
-        println!("===== =====\n");
-
-        all_about_select_json(db).await?;
-    }
-
-    println!("===== =====\n");
-
-    find_all_stream(db).await.unwrap();
-
-    println!("===== =====\n");
-
-    find_first_page(db).await.unwrap();
-
-    println!("===== =====\n");
-
-    find_num_pages(db).await.unwrap();
-
     Ok(())
 }
 
diff --git a/src/executor/select.rs b/src/executor/select.rs
index afd300d5..cd7d122c 100644
--- a/src/executor/select.rs
+++ b/src/executor/select.rs
@@ -1054,10 +1054,8 @@ where
                 } else {
                     acc.insert(key, vec![value]);
                 }
-            } else {
-                if acc.get(&key).is_none() {
-                    acc.insert(key, vec![]);
-                }
+            } else if acc.get(&key).is_none() {
+                acc.insert(key, vec![]);
             }
 
             acc