Update from Sync Service

数据库/去重.md

@@ -1,15 +1,57 @@
-begin tran
+# 数据去重方法
+
+> SQL Server 数据去重常用方法
+
+## 方法一：使用 DISTINCT
 
 ```sql
-select distinct * into #temp from DataSyncStationSX
+SELECT DISTINCT * FROM TableName
-delete DataSyncStationSX
-go
-insert DataSyncStationSX select * from #temp Sqlclub
-go
-drop table #temp
-
-select * from DataSyncStationSX
 ```
-order by sid
 
-commit
+## 方法二：临时表去重
+
+```sql
+BEGIN TRAN
+
+-- 1. 选中不重复的数据到临时表
+SELECT DISTINCT * INTO #temp FROM DataSyncStationSX
+
+-- 2. 删除原表数据
+DELETE FROM DataSyncStationSX
+
+-- 3. 从临时表导回
+INSERT INTO DataSyncStationSX SELECT * FROM #temp
+
+-- 4. 删除临时表
+DROP TABLE #temp
+
+COMMIT
+```
+
+## 方法三：ROW_NUMBER 去重
+
+```sql
+-- 删除重复数据，保留最新一条
+DELETE FROM TableName
+WHERE ID IN (
+    SELECT ID FROM (
+        SELECT ID, ROW_NUMBER() OVER (PARTITION BY duplicate_column ORDER BY created_time DESC) AS rn
+        FROM TableName
+    ) t
+    WHERE rn > 1
+)
+```
+
+## 方法四：查找重复数据
+
+```sql
+-- 查找重复记录
+SELECT column1, column2, COUNT(*) as cnt
+FROM TableName
+GROUP BY column1, column2
+HAVING COUNT(*) > 1
+```
+
+---
+
+> ⚠️ 执行删除前请先备份数据！

数据库/循环批量删除数据库表.md

@@ -1,55 +1,58 @@
---创建临时表
+# 循环批量删除数据库表
-```sql
-create table #Man(
-```
-id int identity(1,1),
-tbName nvarchar(50)
-)   --往临时表插入数据
-```sql
-insert into #Man
-select name from sys.tables
-where create_date<='2018-03-10 15:36:35.687' and name not in ('DeviceNetState','EphInfo','FilterStatistic','UserInfo','AlmInfo')
-```
-order by create_date desc
 
---确认
+> SQL Server 批量删除指定条件的表
-```sql
-select * from #Man
 
-```
+## 存储过程
-commit
-rollback
-begin tran
-
-
---定义循环变量
-```sql
-declare @i int
-set @i = 1
-declare @count int
-select @count = count(*) from #Man
-
-```
---print @count
 
 ```sql
-declare @str nvarchar(500)
+-- 创建临时表存储表名
-declare @tb nvarchar(50)
+CREATE TABLE #Man (
+    id INT IDENTITY(1,1),
+    tbName NVARCHAR(50)
+)
 
-```
+-- 插入要删除的表名（排除保留表）
-while(@i <= @count) begin
+INSERT INTO #Man
+SELECT name 
+FROM sys.tables
+WHERE create_date <= '2018-03-10 15:36:35.687'
+  AND name NOT IN ('DeviceNetState', 'EphInfo', 'FilterStatistic', 'UserInfo', 'AlmInfo')
+ORDER BY create_date DESC
 
-```sql
+-- 确认要删除的表
-select @tb = isnull(tbName, '') from #Man where id = @i
+SELECT * FROM #Man
-```
---循环执行语句
-```sql
-set @str = 'drop table [' + @tb+ ']'
-```
-exec(@str)
 
-```sql
+-- 开始删除
-set @str = ''
+DECLARE @i INT = 1
-set @i = @i + 1
+DECLARE @count INT
+SELECT @count = COUNT(*) FROM #Man
+
+DECLARE @str NVARCHAR(500)
+DECLARE @tb NVARCHAR(50)
+
+WHILE (@i <= @count)
+BEGIN
+    SELECT @tb = ISNULL(tbName, '') FROM #Man WHERE id = @i
+    
+    SET @str = 'DROP TABLE [' + @tb + ']'
+    EXEC(@str)
+    
+    SET @i = @i + 1
+END
+
+-- 清理临时表
+DROP TABLE #Man
 ```
-end
+
+---
+
+## 安全建议
+
+1. **先 SELECT 确认**：删除前先只 SELECT，确认无误再执行 DELETE
+2. **排除保留表**：一定要排除系统表和重要业务表
+3. **备份**：生产环境先备份再执行
+4. **分批执行**：大量删除时分批进行，避免锁表时间过长
+
+---
+
+> ⚠️ **警告**：此操作不可逆，执行前务必确认！