来自 Python 的复杂 SQL Server 查询

Posted 2023-04-12

【中文标题】来自 Python 的复杂 SQL Server 查询

【英文标题】：Complex SQL Server query from Python

【发布时间】：2016-11-15 10:20:18

【问题描述】：

我有一个复杂的 SQL Server 查询，需要从 python 执行。

SQL 查询如下所示：

SELECT * 
FROM(
    SELECT DATEADD(HOUR, CONVERT(INT, SUBSTRING(hour_id, 2, 2)), CAST(FECHA as DATETIME)) as 'Time_', value
    FROM
        (
        SELECT * FROM [MyTable]
        ) as sel
    UNPIVOT(value for hour_id in (H01, H02, H03, H04, H05, H06, H07, H08, H09, H10, H11, H12, H13, H14, H15, H16, H17, H18, H19, H20, H21, H22, H23, H24) ) as unpvte
) as Q1;

我创建了一个函数来运行查询并将结果转为 Pandas：

import pandas as pd
import numpy as np
import datetime
import pypyodbc

def execute_sql_command(database_name, server_name, user, password, SQLCommand, index_col=0):
        """
        Executed a query in an SQL Server database and returns a Pandas DataFrame
        :param database_name: Name of the Database
        :param SQLCommand: SQL command with no comments
        :param index_col: Index of the column
        :return: Pandas DataFrame
        """

        connection_string = 'DRIVER=SQL Server;Database=' + database_name \
                            + ';SERVER=' + server_name \
                            + ';UID=' + user \
                            + ';PWD=' + password

        connection = pypyodbc.connect(connection_string)
        cursor = connection.cursor()

        data = list()
        idx = list()
        cursor.execute(SQLCommand)
        hdr = [tuple[0] for tuple in cursor.description]

        hdr.pop(index_col)

        results = cursor.fetchone()
        if results is not None:
            results = list(results)

        while results:
            idx.append(results[index_col])  # add the index
            results.pop(index_col)  # remove the index from the row (we already accounted for it)
            data.append(results)  #
            results = cursor.fetchone()
            if results is not None:
                results = list(results)

        connection.close()

        data = np.array(data)
        df = pd.DataFrame(data=data, columns=hdr, index=idx)

        return df

我收到此错误：

pypyodbc.ProgrammingError: ('42000', "[42000] [Microsoft][ODBC SQL 服务器驱动程序][SQL Server]靠近 'L' 的语法不正确。")

我的代码适用于像 SELECT * FROM Table 这样的简单查询，但对于这个复杂的查询却失败了。该查询在 Microsoft SQL Server Management Studio 中运行。

【参考方案1】：

嗯，我知道问题出在哪里了。

我正在从.sql 文件中读取查询。所以文件必须是UTF-8格式。

然后在一行中编写 SQL 命令，这是删除 \n 字符。