Pyodbc executemany only returns 最后插入的元素

Question

使用以下函数：

import pyodbc

def execute_side_effect_stmt(sql_stmt: str, params: list):
    with get_connection() as conn:
        cursor = conn.cursor()
        cursor.executemany(sql_stmt, params)
        columns = [column[0] for column in cursor.description]
        results = cursor.fetchall()
        response = []
        for row in results:
            response.append(dict(zip(columns, row)))
        conn.commit()
        if not response:
            return ''
        return response

使用以下参数：

sql = """INSERT INTO dbo.events
      (sha, duration)
      OUTPUT Inserted.id, Inserted.sha
      VALUES (?, ?)"""

params = [('123',1),('456', 2), ('789', 3)]

result = execute_side_effect_stmt(sql, params)

结果只有returns id和sha 参数中的最后一个条目。一切都正确地插入到数据库中。非常欢迎任何关于为什么只有最后一个插入给出输出的见解。

Answer 1

原因是cursor.executemany()对params中的每个元素执行了SQL语句。如docs所示，除非您设置cursor.fast_executemany = True，否则INSERT语句将被调用len(params)次。

使用 cursor.fast_executemany = True，结果将是单个插入，如 here

所述

如描述：

Here, all the parameters are sent to the database server in one bundle (along with the SQL statement), and the database executes the SQL against all the parameters as one database transaction. Hence, this form of executemany() should be much faster than the default executemany(). However, there are limitations to it, see fast_executemany for more details.

您的代码可以修改为：

import pyodbc

def execute_side_effect_stmt(sql_stmt: str, params: list):
    with get_connection() as conn:
        cursor = conn.cursor()
        cursor.fast_executemany = True
        cursor.executemany(sql_stmt, params)
        columns = [column[0] for column in cursor.description]
        results = cursor.fetchall()
        response = []
        for row in results:
            response.append(dict(zip(columns, row)))
        conn.commit()
        if not response:
            return ''
        return response

Pyodbc executemany only returns 最后插入的元素

Pyodbc executemany only returns last element inserted

python

database

insert

pyodbc