怎样用python+sqlalchemy获得mssql视图对应物理表关系(二)

ops/2024/10/21 5:47:59/

话不多说

目标:为了实现低代码数据视图对接,有必要得到视图所对应物理表及字段名称,字段类型等

1)约束:视图中用到的物理表不能起别名,所以修改上一篇中存储过程建立语句

USE [agui_conn]
GO
/****** Object:  StoredProcedure [dbo].[sp_GetOrdersByTimestamp]    Script Date: 09/29/2024 14:40:36 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[sp_GetOrdersByTimestamp]@Timestamp NVARCHAR(100),@Condition NVARCHAR(100) -- 假设这是一个额外的条件，如订单状态
AS
BEGINIF OBJECT_ID('dbo.vw_OrdersByTimestamp', 'V') IS NOT NULLBEGINEXEC sp_executesql N'DROP VIEW dbo.vw_OrdersByTimestamp';END-- 创建一个视图来显示所需的订单信息DECLARE @sql NVARCHAR(MAX);SET @sql = N'CREATE VIEW dbo.vw_OrdersByTimestamp ASSELECT Users.Username as 用户名, Orders.OrderTime as 订单时间,Orders.Amount as 订单金额,'''+ @Timestamp + ''' AS 查询时间FROM OrdersINNER JOIN Users ON Orders.UserId = Users.UserIdWHERE (Orders.Status = ''' + @Condition+ ''')'; -- 假设订单表中有一个Status字段o.OrderTime >= ''' + CONVERT(NVARCHAR, @Timestamp, 120) + ''' ANDEXEC sp_executesql @sql;END

2)在 SQL Server 中，用存储过程创建的视图没有出现在 sys.views 中，尝试查询 sys.objects 来获取所有对象的列表:

SELECT OBJECT_SCHEMA_NAME(object_id) AS SchemaName,OBJECT_NAME(object_id) AS ViewName
FROM sys.objects
WHERE OBJECTPROPERTY(object_id, 'IsView') = 1;

3)通过sys.objects获得指定视图的描述

SchemaName='dbo'ViewName='vw_OrdersByTimestamp'create_view_query = text(f"""SELECT OBJECT_DEFINITION(OBJECT_ID('{SchemaName}.{ViewName}')) as ViewDefinitionFROM sys.objectsWHERE OBJECTPROPERTY(object_id, 'IsView') = 1AND OBJECT_NAME(object_id) = '{ViewName}'AND OBJECT_SCHEMA_NAME(object_id) = '{SchemaName}'""")result = conn.execute(create_view_query)create_view_result = result.fetchone()view_creation_sql=create_view_result['ViewDefinition']print(view_creation_sql)

结果如图:

4)用正则表达式匹配视图字段名和对应的物理表名及字段名

# 正则表达式匹配视图字段名和对应的物理表名及字段名column_pattern = re.compile(r"(\w+\.\w+) as (\w+)", re.IGNORECASE)# 提取字段映射columns_mapping = column_pattern.findall(view_creation_sql)# 常量值匹配constant_pattern = re.compile(r"'([^']*)' AS (\w+)", re.IGNORECASE)constants_mapping = constant_pattern.findall(view_creation_sql)field_dict = {}for column, alias in columns_mapping:field_dict[f'{alias}'] = columnfor constant, alias in constants_mapping:field_dict[f'{alias}'] = None# 反射视图的列信息table = Table(view_name, metadata, autoload=True, autoload_with=engine)for column in table.columns:v_field = f"{column.name}"tb_field = field_dict[v_field]print(f"视图字段名: {column.name}, 对应表字段: {tb_field}, 数据类型: {column.type}")

最终实现结果