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sql - 比较两个表并找出列值的差异

问题描述

我想比较两个表（相同的列）并找出哪些列值发生了变化。

这是示例数据的示例。

employee_original表有 6 列。

CREATE TABLE [dbo].[employee_original](
    [emp_id] [int] IDENTITY(1,1) NOT NULL,
    [first_name] [varchar](100) NOT NULL,
    [last_name] [varchar](100) NOT NULL,
    [salary] int NOT NULL,
    [city] [varchar](20) NOT NULL,
    [department] [varchar](20) NOT NULL,
PRIMARY KEY CLUSTERED 
(
    [emp_id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 90) ON [PRIMARY]
) ON [PRIMARY]
GO

INSERT INTO employee_original VALUES ( 'Julia', 'Schultz', 100, 'New York', 'Tech');
INSERT INTO employee_original VALUES ( 'Vincent', 'Trantow', 200, 'Moscow', 'HR');
INSERT INTO employee_original VALUES ( 'Whitney ', 'Pouros', 500, 'Miami', 'Accounting');
INSERT INTO employee_original VALUES ( 'Chandler', 'Osinski', 10, 'Singapore', 'Purchasing');
INSERT INTO employee_original VALUES ( 'Sydnie', 'Green', 700, 'Ireland', 'Operations');
INSERT INTO employee_original VALUES ( 'Josefa', 'Anderson', 800, 'Berlin', 'Purchase');
INSERT INTO employee_original VALUES ( 'Brayan', 'Bergstrom', 900, 'New York', 'Operations');
INSERT INTO employee_original VALUES ( 'Shyanne', 'Kris', 900, 'New York', 'Sales');

employee_modified具有相同的员工，但少数员工的某些属性已更改。

CREATE TABLE [dbo].[employee_modified](
    [emp_id] [int] IDENTITY(1,1) NOT NULL,
    [first_name] [varchar](100) NOT NULL,
    [last_name] [varchar](100) NOT NULL,
    [salary] int NOT NULL,
    [city] [varchar](20) NOT NULL,
    [department] [varchar](20) NOT NULL,
PRIMARY KEY CLUSTERED 
(
    [emp_id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 90) ON [PRIMARY]
) ON [PRIMARY]
GO

INSERT INTO employee_modified VALUES ( 'Julia', 'Schultz', 100, 'New York', 'Tech');
INSERT INTO employee_modified VALUES ( 'Vincent', 'Wyman', 500, 'Moscow', 'HR');
INSERT INTO employee_modified VALUES ( 'Whitney ', 'Pouros', 500, 'Miami', 'Sales');
INSERT INTO employee_modified VALUES ( 'Chandler', 'Osinski', 10, 'Singapore', 'Purchasing');
INSERT INTO employee_modified VALUES ( 'Sydnie', ' Cartwright', 900, 'Ireland', 'Operations');
INSERT INTO employee_modified VALUES ( 'Joseph', 'Anderson', 800, 'Berlin', 'Purchase');
INSERT INTO employee_modified VALUES ( 'Bryan', 'Bergstrom', 900, 'Naples', 'Operations');
INSERT INTO employee_modified VALUES ( 'Shyanne', 'Jakubowski', 900, 'New York', 'Accounting');

我正在寻找可以告诉我哪个员工更改了哪个字段的结果。例如emp_id =2 有姓氏和薪水变化。所以输出应该是这样的：

emp_id  attribute   orignial_value  new_value
2       last_name   Trantow         Wyman
2       salary      200             500

这是我到目前为止所尝试的：

(1) 加入表格并找出改变的地方：

DROP TABLE IF EXISTS #temp;

SELECT      distinct 
            o.emp_id,
            o.first_name [original_first_name], m.first_name [modified_first_name],
            o.last_name [original_last_name], m.last_name [modified_last_name],
            o.salary [original_salary], m.salary [modified_salary],
            o.city [original_city], m.city [modified_city],
            o.department [original_department], m.department [modified_department]
            into #temp from  
            [dbo].[employee_original] o inner join [dbo].[employee_modified] m on o.emp_id = m.emp_id

select * from #temp

给我

在此处输入图像描述

(2) 自加入#temp并找出哪些属性发生了变化。

-- All Last Name Changes. 
select distinct t1.emp_id, t1.original_last_name, t2.modified_last_name
        from #temp t1
            inner join #temp t2 on t1.emp_id = t2.emp_id
        where t1.original_last_name <> t2.modified_last_name

-- All Department changes
select distinct t1.emp_id, t1.original_department, t2.modified_department
        from #temp t1
            inner join #temp t2 on t1.emp_id = t2.emp_id
        where t1.original_department <> t2.modified_department

关于如何达到我想要的结果的任何指示。

标签： sqlsql-servertsql

解决方案

您可以使用以下代码取消透视所有可能的更改

SELECT
  o.emp_id,
  v.column_name,
  v.old_value,
  v.new_value
FROM employee_original o
JOIN employee_modified m ON o.emp_id = m.emp_id
CROSS APPLY (
    SELECT 'first_name', CAST(o.first_name AS nvarchar(max)), CAST(m.first_name AS nvarchar(max))
      WHERE o.first_name <> m.first_name
    UNION ALL
    SELECT 'last_name', o.last_name, m.last_name
      WHERE o.last_name <> m.last_name
    UNION ALL
    SELECT 'salary', o.salary, m.salary
      WHERE o.salary <> m.salary
    UNION ALL
    SELECT 'city', o.city, m.city
      WHERE o.city <> m.city
    UNION ALL
    SELECT 'department', o.department, m.department
      WHERE o.department <> m.department
) v(column_name, old_value, new_value);

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