Difference between bulk update with FROM VALUES and without it?

還沒有人認領這個 Issue。

```python3
await conn.executemany(
"""
UPDATE user SET login=$2, name=$3, age=$4, sex=$5
WHERE id=$1
""",
users,
)
```

```python3
await conn.executemany(
"""
UPDATE user SET login=actual_user.login, name=actual_user.name, age=actual_user.age, sex=actual_user.sex
FROM (VALUES ($1, $2, $3, $4, $5)) AS actual_user (id, login, name, age::integer, sex::integer)
WHERE user.id=actual_user.id
""",
users,
)
```

The first is cleaner. But I worry about performance. I know the second is performed as one request. But the first is the same?

Is there any reason to use the second way?

從 asyncpg 的 executemany 入口點和 PostgreSQL 的 UPDATE ... FROM VALUES 語意開始，同時比較 SQL 範例及其請求行為。完成標準是清楚地記錄並說明這些方法在效能或用途上是否有所不同，以及第二種形式何時有用。

由索引模型根據 Issue 內容生成。