SQLAlchemy中使用UPSERT的操作方法_MsSqlserver

前言

sqlite 和 postgresql 都支持 upsert 操作，即"有则更新，无则新增"。冲突列必须有唯一约束。

语法：

postgresql: insert ... on conflict (column) do update/nothing
sqlite: insert ... on conflict(column) do update/nothing。注意括号位置

场景	postgresql	sqlite	说明
基本 upsert	`on conflict (col) do update set ...`	`on conflict(col) do update set ...`	括号位置略有不同
冲突忽略	`on conflict (col) do nothing`	`on conflict(col) do nothing`	相同
引用新值	`excluded.col`	`excluded.col`	postgresql 大写，sqlite 小写
返回结果	`returning *`	`returning *`	相同
条件更新	`where condition`	不支持 where	sqlite 限制

注意事项

冲突列必须有唯一约束
postgresql 和 sqlite 的语法相似，但仍有细微差别。使用原生 sql 时需要注意。
sqlite 在 upsert 时不支持 where 子句，需要改用 case 表达式或应用层过滤。
sqlite 3.35+ 版本才支持 returning

excluded 和 returning

excluded

excluded 表示冲突时被拦截的新值。

insert into users (email, name, age)
values ('test@example.com', '新名字', 30)
on conflict (email) do update set
    name = excluded.name,   -- ← 引用新值 "新名字"
    age = excluded.age      -- ← 引用新值 30

场景	表达式	含义	示例值
原表字段	`users.name`	冲突行的当前值	"老名字"
新值字段	`excluded.name`	试图插入的新值	"新名字"
混合计算	`users.age + excluded.age`	原值 + 新值	25 + 30 = 55

示例 1：累加库存

-- 商品库存累加：原库存 100 + 新增 50 = 150
insert into products (sku, stock)
values ('iphone15', 50)
on conflict (sku) do update set
    stock = products.stock + excluded.stock  -- 100 + 50
returning stock;

示例 2：仅更新非空字段

-- 如果新值为 null，保留原值
insert into users (email, name, age)
values ('test@example.com', '新名字', null)
on conflict (email) do update set
    name = coalesce(excluded.name, users.name),  -- 新名字
    age = coalesce(excluded.age, users.age)      -- 保留原 age

示例 3：时间戳更新

-- 更新时刷新 updated_at
insert into users (email, name)
values ('test@example.com', '新名字')
on conflict (email) do update set
    name = excluded.name,
    updated_at = now()  -- postgresql
    -- updated_at = current_timestamp  -- sqlite

returning

returning 用于返回操作结果。在 insert/update/delete 后直接返回指定列，避免额外 select 查询：

insert into users (email, name)
values ('test@example.com', '张三')
returning id, email, name, created_at;

示例 1：插入后立即获取 id

# postgresql / sqlite 3.35+
sql = text("""
    insert into users (email, name)
    values (:email, :name)
    returning id, email, created_at
""")
result = await session.execute(sql, {"email": "test@example.com", "name": "张三"})
user = result.mappings().first()
print(user["id"])  # 直接获取 id

示例 2：upsert 后统一返回

-- 无论插入还是更新，都返回最终状态
insert into users (email, name, login_count)
values ('test@example.com', '张三', 1)
on conflict (email) do update set
    name = excluded.name,
    login_count = users.login_count + 1  -- 累加登录次数
returning 
    id,
    email,
    name,
    login_count,
    case 
        when xmax = 0 then 'inserted'  -- postgresql 特有：xmax=0 表示插入
        else 'updated'
    end as action

示例 3：批量操作返回所有结果

-- postgresql 支持批量 returning
insert into users (email, name)
values 
    ('a@example.com', 'a'),
    ('b@example.com', 'b')
on conflict (email) do update set
    name = excluded.name
returning id, email, name;

python 处理批量返回：

result = await session.execute(sql)
users = [dict(row) for row in result.mappings().all()]
# [{'id': 1, 'email': 'a@example.com', 'name': 'a'}, ...]

示例：用户登录计数器

async def record_user_login(session: asyncsession, email: str, name: str) -> dict:
    """
    用户登录计数器：
    - 新用户：插入，login_count = 1
    - 老用户：更新，login_count += 1
    - 返回最终状态 + 操作类型
    """
    sql = text("""
        insert into users (
            email, name, login_count, last_login, created_at
        ) values (
            :email, :name, 1, :now, :now
        )
        on conflict (email) do update set
            name = excluded.name,                          -- 更新用户名
            login_count = users.login_count + 1,           -- 累加登录次数
            last_login = excluded.last_login               -- 更新最后登录时间
        returning
            id,
            email,
            name,
            login_count,
            last_login,
            created_at,
            case 
                when xmax = 0 then 'inserted' 
                else 'updated' 
            end as action  -- postgresql 特有：区分插入/更新
    """)
    now = datetime.utcnow()
    result = await session.execute(
        sql,
        {"email": email, "name": name, "now": now}
    )
    row = result.mappings().first()
    return dict(row) if row else none
# 使用示例
user = await record_user_login(session, "test@example.com", "张三")
print(f"{user['action']} user {user['email']} with {user['login_count']} logins")
# 输出: inserted user test@example.com with 1 logins
# 或: updated user test@example.com with 5 logins

示例数据模型类

from sqlalchemy import column, integer, string, uniqueconstraint
from sqlalchemy.orm import declarativebase
class base(declarativebase):
    pass
class user(base):
    __tablename__ = "users"
    id = column(integer, primary_key=true, autoincrement=true)
    email = column(string(100), unique=true, nullable=false)  # 唯一约束
    name = column(string(50))
    age = column(integer)
    balance = column(integer, default=0)
    __table_args__ = (
        uniqueconstraint("email", name="uq_users_email"),
    )
class product(base):
    __tablename__ = "products"
    id = column(integer, primary_key=true)
    sku = column(string(50), unique=true, nullable=false)  # 唯一 sku
    name = column(string(100))
    stock = column(integer, default=0)
    price = column(integer)

orm 方式

注意 insert 的导入路径。

基本示例

from sqlalchemy.dialects.postgresql import insert as pg_insert
from sqlalchemy.dialects.sqlite import insert as sqlite_insert
from sqlalchemy import insert
async def upsert_user_orm(session: asyncsession, user_data: dict) -> dict:
    """
    upsert 用户（orm 风格）
    如果 email 冲突则更新，否则插入
    """
    # 方式 1：使用通用 insert（推荐⭐）
    # sqlalchemy 会根据方言自动选择正确的语法
    stmt = (
        insert(user)
        .values(**user_data)
        .on_conflict_do_update(
            index_elements=["email"],  # 冲突检测列（唯一约束）
            set_={
                "name": user_data["name"],
                "age": user_data.get("age"),
                "updated_at": func.now()  # 假设有 updated_at 列
            }
        )
        .returning(user)  # 返回插入/更新后的行
    )
    result = await session.execute(stmt)
    user = result.scalar_one()
    return {
        "id": user.id,
        "email": user.email,
        "name": user.name,
        "age": user.age
    }
async def upsert_user_ignore(session: asyncsession, user_data: dict) -> bool:
    """
    upsert 但冲突时忽略（do nothing）
    """
    stmt = (
        insert(user)
        .values(**user_data)
        .on_conflict_do_nothing(
            index_elements=["email"]
        )
    )
    result = await session.execute(stmt)
    return result.rowcount > 0  # 返回是否插入成功

条件更新：仅更新特定字段

async def upsert_user_conditional(session: asyncsession, user_data: dict) -> dict:
    """
    upsert：冲突时只更新非空字段
    """
    stmt = (
        insert(user)
        .values(**user_data)
        .on_conflict_do_update(
            index_elements=["email"],
            set_={
                "name": user_data["name"],
                # 条件：只有提供了 age 才更新
                "age": user_data.get("age", user.age),  # 保持原值
            },
            # 可选：添加 where 条件
            where=user.email == user_data["email"]
        )
        .returning(user)
    )
    result = await session.execute(stmt)
    return result.mappings().first()

批量 upsert

async def bulk_upsert_users(session: asyncsession, users: list[dict]) -> int:
    """
    批量 upsert 用户
    """
    stmt = (
        insert(user)
        .values(users)
        .on_conflict_do_update(
            index_elements=["email"],
            set_={
                "name": insert(user).excluded.name,  # 使用 excluded 表示新值
                "age": insert(user).excluded.age,
            }
        )
    )
    result = await session.execute(stmt)
    return result.rowcount

使用 excluded 引用新值

async def upsert_product_with_stock(session: asyncsession, product_data: dict) -> dict:
    """
    upsert 产品：冲突时累加库存
    """
    stmt = (
        insert(product)
        .values(**product_data)
        .on_conflict_do_update(
            index_elements=["sku"],
            set_={
                # 累加库存：原库存 + 新库存
                "stock": product.stock + insert(product).excluded.stock,
                # 更新其他字段
                "name": insert(product).excluded.name,
                "price": insert(product).excluded.price,
            }
        )
        .returning(product)
    )
    result = await session.execute(stmt)
    return result.mappings().first()

用户服务

class userservice:
    """用户服务（支持 upsert）"""
    def __init__(self, session: asyncsession):
        self.session = session
    async def create_or_update(self, email: str, name: str, age: int | none = none) -> dict:
        """创建或更新用户"""
        stmt = (
            insert(user)
            .values(
                email=email,
                name=name,
                age=age,
                created_at=datetime.utcnow()
            )
            .on_conflict_do_update(
                index_elements=["email"],
                set_={
                    "name": name,
                    "age": age,
                    "updated_at": datetime.utcnow()
                }
            )
            .returning(user)
        )
        result = await self.session.execute(stmt)
        user = result.scalar_one()
        return {
            "id": user.id,
            "email": user.email,
            "name": user.name,
            "age": user.age
        }
    async def bulk_create_or_update(self, users: list[dict]) -> int:
        """批量创建或更新"""
        stmt = (
            insert(user)
            .values(users)
            .on_conflict_do_update(
                index_elements=["email"],
                set_={
                    "name": insert(user).excluded.name,
                    "age": insert(user).excluded.age,
                    "updated_at": datetime.utcnow()
                }
            )
        )
        result = await self.session.execute(stmt)
        return result.rowcount
    async def create_if_not_exists(self, email: str, name: str) -> bool:
        """仅当不存在时创建"""
        stmt = (
            insert(user)
            .values(
                email=email,
                name=name,
                created_at=datetime.utcnow()
            )
            .on_conflict_do_nothing(
                index_elements=["email"]
            )
        )
        result = await self.session.execute(stmt)
        return result.rowcount > 0  # true = 插入成功，false = 已存在

原生 sql

基本示例

postgresql

async def upsert_user_pg(session: asyncsession, user_data: dict) -> dict | none:
    """
    postgresql 原生 upsert
    """
    sql = text("""
        insert into users (email, name, age, created_at)
        values (:email, :name, :age, :created_at)
        on conflict (email) do update  -- 冲突列
        set 
            name = excluded.name,      -- excluded 表示新插入的值
            age = excluded.age,
            updated_at = now()
        returning id, email, name, age
    """)
    result = await session.execute(
        sql,
        {
            "email": user_data["email"],
            "name": user_data["name"],
            "age": user_data.get("age"),
            "created_at": datetime.utcnow()
        }
    )
    row = result.mappings().first()
    return dict(row) if row else none

sqlite

async def upsert_user_sqlite(session: asyncsession, user_data: dict) -> dict | none:
    """
    sqlite 原生 upsert（语法与 postgresql 几乎相同）
    """
    sql = text("""
        insert into users (email, name, age, created_at)
        values (:email, :name, :age, :created_at)
        on conflict(email) do update set  -- sqlite 语法稍有不同
            name = excluded.name,
            age = excluded.age,
            updated_at = current_timestamp
        returning id, email, name, age
    """)
    result = await session.execute(
        sql,
        {
            "email": user_data["email"],
            "name": user_data["name"],
            "age": user_data.get("age"),
            "created_at": datetime.utcnow()
        }
    )
    row = result.mappings().first()
    return dict(row) if row else none

冲突时忽略

async def insert_or_ignore_user(session: asyncsession, user_data: dict) -> bool:
    """
    插入用户，如果冲突则忽略
    """
    # postgresql
    sql = text("""
        insert into users (email, name, age, created_at)
        values (:email, :name, :age, :created_at)
        on conflict (email) do nothing
    """)
    # sqlite（语法相同）
    # sql = text("""
    #     insert into users (email, name, age, created_at)
    #     values (:email, :name, :age, :created_at)
    #     on conflict(email) do nothing
    # """)
    result = await session.execute(
        sql,
        {
            "email": user_data["email"],
            "name": user_data["name"],
            "age": user_data.get("age"),
            "created_at": datetime.utcnow()
        }
    )
    return result.rowcount > 0  # 返回是否插入成功

批量 upsert

async def bulk_upsert_products(session: asyncsession, products: list[dict]) -> int:
    """
    批量 upsert 产品（原生 sql）
    """
    # postgresql
    sql = text("""
        insert into products (sku, name, stock, price, created_at)
        values (
            :sku, :name, :stock, :price, :created_at
        )
        on conflict (sku) do update set
            name = excluded.name,
            stock = products.stock + excluded.stock,  -- 累加库存
            price = excluded.price,
            updated_at = now()
    """)
    # 批量执行
    for product in products:
        await session.execute(
            sql,
            {
                "sku": product["sku"],
                "name": product["name"],
                "stock": product.get("stock", 0),
                "price": product.get("price", 0),
                "created_at": datetime.utcnow()
            }
        )
    return len(products)

部分更新 + 条件判断

async def upsert_user_smart(session: asyncsession, user_data: dict) -> dict | none:
    """
    智能 upsert：
    - 如果提供了 age，才更新 age
    - 如果提供了 name，才更新 name
    - 更新 updated_at
    """
    sql = text("""
        insert into users (email, name, age, created_at)
        values (:email, :name, :age, :created_at)
        on conflict (email) do update set
            name = coalesce(:name, users.name),  -- 如果新值为 null，保持原值
            age = coalesce(:age, users.age),
            updated_at = now()
        returning id, email, name, age, updated_at
    """)
    result = await session.execute(
        sql,
        {
            "email": user_data["email"],
            "name": user_data.get("name"),  # 可能为 none
            "age": user_data.get("age"),    # 可能为 none
            "created_at": datetime.utcnow()
        }
    )
    row = result.mappings().first()
    return dict(row) if row else none

用户注册/登录：存在则更新最后登录时间

async def register_or_login(session: asyncsession, email: str, name: str) -> dict:
    """
    用户注册或登录：
    - 新用户：插入
    - 老用户：更新最后登录时间
    """
    sql = text("""
        insert into users (email, name, last_login, created_at)
        values (:email, :name, :now, :now)
        on conflict (email) do update set
            last_login = excluded.last_login,
            name = excluded.name  -- 可选：更新用户名
        returning id, email, name, last_login, created_at
    """)
    now = datetime.utcnow()
    result = await session.execute(
        sql,
        {"email": email, "name": name, "now": now}
    )
    return dict(result.mappings().first())

库存累加

async def add_product_stock(session: asyncsession, sku: str, quantity: int) -> bool:
    """
    增加商品库存：
    - 商品不存在：插入
    - 商品存在：累加库存
    """
    sql = text("""
        insert into products (sku, stock, created_at)
        values (:sku, :quantity, :now)
        on conflict (sku) do update set
            stock = products.stock + excluded.stock,
            updated_at = now()
    """)
    result = await session.execute(
        sql,
        {
            "sku": sku,
            "quantity": quantity,
            "now": datetime.utcnow()
        }
    )
    return result.rowcount > 0

用户积分累加

async def add_user_points(session: asyncsession, user_id: int, points: int) -> dict | none:
    """
    增加用户积分（累加）
    """
    sql = text("""
        insert into user_points (user_id, points, created_at)
        values (:user_id, :points, :now)
        on conflict (user_id) do update set
            points = user_points.points + excluded.points,
            updated_at = now()
        returning user_id, points
    """)
    result = await session.execute(
        sql,
        {
            "user_id": user_id,
            "points": points,
            "now": datetime.utcnow()
        }
    )
    row = result.mappings().first()
    return dict(row) if row else none

标签计数

存在则 +1，不存在则创建：

async def increment_tag_count(session: asyncsession, tag_name: str) -> int:
    """
    标签计数：
    - 标签不存在：插入 count=1
    - 标签存在：count += 1
    """
    sql = text("""
        insert into tags (name, count, created_at)
        values (:name, 1, :now)
        on conflict (name) do update set
            count = tags.count + 1,
            updated_at = now()
        returning count
    """)
    result = await session.execute(
        sql,
        {"name": tag_name, "now": datetime.utcnow()}
    )
    return result.scalar() or 0

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