Transaction (SeaQL/sea-orm#142)

SeaORM/docs/01-index.md

@@ -76,6 +76,8 @@
 
 	6.5 [More joins](/docs/advanced-query/more-join)
 
+	6.6 [Transaction](/docs/advanced-query/transaction)
+
 7. Internal Design
 
 	7.1 [Traits and Types](/docs/internal-design/trait-and-type)

SeaORM/docs/07-advanced-query/06-transaction.md

@@ -0,0 +1,58 @@
+# Transaction
+
+You can perform atomic operations inside transaction. There are two transaction APIs available to you.
+
+## `Closure` style
+
+Transaction will be committed if the closure returned `Ok`, rollbacked if `Err`.
+
+```rust
+db.transaction::<_, _, DbErr>(|txn| {
+    Box::pin(async move {
+        bakery::ActiveModel {
+            name: Set("SeaSide Bakery".to_owned()),
+            profit_margin: Set(10.4),
+            ..Default::default()
+        }
+        .save(txn)
+        .await?;
+
+        bakery::ActiveModel {
+            name: Set("Top Bakery".to_owned()),
+            profit_margin: Set(15.0),
+            ..Default::default()
+        }
+        .save(txn)
+        .await?;
+
+        Ok(())
+    })
+})
+.await;
+```
+
+## `Begin` ... `commit` / `rollback` style
+
+`Begin` the transaction followed by `commit` or `rollback`. If `txn` goes out of scope, it'd automatically rollback.
+
+```rust
+let txn = db.begin().await?;
+
+bakery::ActiveModel {
+    name: Set("SeaSide Bakery".to_owned()),
+    profit_margin: Set(10.4),
+    ..Default::default()
+}
+.save(&txn)
+.await?;
+
+bakery::ActiveModel {
+    name: Set("Top Bakery".to_owned()),
+    profit_margin: Set(15.0),
+    ..Default::default()
+}
+.save(&txn)
+.await?;
+
+txn.commit().await?;
+```