INSERT OR UPDATE操作允许你在单个语句中执行插入或更新操作。如果记录不存在,则插入新记录;如果记录存在,则更新现有记录。SQL Server提供了多种方式来实现这一操作,包括使用MERGE语句、IF EXISTS条件和UPSERT函数(在某些情况下)。 优势 简化代码:通过单个语句完成插入和更新操作,减少了代码复杂性。 提高效率:减少了数据...
You do an insert with the data and if you've got an existing unique key (which isn't auto-incremented), if it exists, the insert will throw an error.Catch the error and then do an update.OrUse auto-incremented primary key and all inserts will be on a new line.Or...
INSERTINTOtable(SELECTid,'hisname'asnameFROMtableWHEREid>=3)ONDUPLICATEKEYUPDATEname=VALUES(name); 这种方法还可以用来批量执行UPDATE操作(因为单条UPDATE语句只能执行一种update操作) 方法二: 创建存储过程 CREATEPROCEDUREname()ifexists(select1from表whereID=@ID)beginUPDATE表SETXX=XXWHEREID=@IDendelsebeginI...
fsql.InsertOrUpdate<T>().SetSource(items)//Data to be processed//.IfExistsDoNothing() //If the data exists, do nothing (that means, insert the data if and only if the data does not exist)//.UpdateSet((a, b) => a.Count == b.Count + 10).ExecuteAffrows();//or..varsql=fsq...
有的时候会需要写一段insert的sql，如果主键存在，则update；如果主键不存在，则insert。Mysql中提供了...
Vibhore, While it is true that the update statement is doing nothing if you are just doing inserts, it is no less performant that using if (exists). In the case of an insert, both will perform one table scan (or index search) to perform the insert. In the case of Update first, it...
SQL(sql)语句大全 一、mysql基本指令 show databases 显示当前数据库 use mysql 使用当前数据库 show tables 显示当前数据库下的表 desc user 查看表结构 create database cd1706 创建数据库 二、创建表 create tableifnot existsperson( id int notnullauto_increment, ...
to_sql('person_age', engine, if_exists='append', index=False) ### Extra data to insert/update extra_data = pd.DataFrame({'id' : [2, 3], 'age' : [44, 95]}) extra_data.set_index('id', inplace=True) ### extra_data.to_sql() with row update or insert option expected_df ...
to be updated if it already exists and inserted if it does not. If we refer to the Books Online documentation, it gives examples that are similar to:IF EXISTS (SELECT * FROM Table1 WHERE Column1='SomeValue') UPDATE Table1 SET (...) WHERE Column1='SomeValue' ELSE INSERT INTO Table1...
<insert id="insertOrUpdate"> if not exists (select 1 from table_name where column_name = XX) insert into table_name(id, update_time) values(1, getdate()) else update table_name set update_time = getdate() where id = 1 </insert> ...