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...
begintran ifexists(select*fromtablewith(updlock,serializable)wherekey=@key)beginupdatetableset...wherekey=@keyendelsebegininsert intotable(key, ...)values(@key, ...)endcommittran 或者 begintranupdatetablewith(serializable)set...wherekey=@keyif @@rowcount=0begininsert intotable(key, ...)values...
CREATE TRIGGER tr_T_A ON T_A for INSERT,UPDATE,DELETE 如IF exists (select * from inserted) and not exists (select * from deleted) 则为 INSERT 如IF exists(select * from inserted ) and exists (select * from deleted) 则为 UPDATE 如IF exists (select * from deleted) and not exists (s...
3. 组合多个INSERT和UPDATE操作: 也可以考虑将INSERT和UPDATE操作组合在一起,以便在一个操作中完成INSERT或更新,而不是使用ON DUPLICATE KEY UPDATE,这种方式可能在逻辑上更方便。例如: 代码语言:sql 复制 STARTTRANSACTION;INSERTINTOtable(id,name)SELECTid+1,'New Name'FROMtableWHEREnotexists(SELECTNULLFROMdbo.ne...
<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> ...
PeopleSex nvarchar(1) default('男') check(PeopleSex='男' or PeopleSex='女'),--性别 --default表示默认值,就是你不在这格里面填,那它默认就是男 --check表示对PeopleSex进行约束, --check(),括号里面表示具体约束上述表示PeopleSex只能是男或女, ...
SELECT IF (EXISTS( SELECT * FROM Terminal WHERE IP_address=10.40.186.7)) UPDATE terminals SET IP_address=10.40.186.7 WHERE ID=1 and Name='anshu' ELSE INSERT INTO Terminal (ID, type_ID, Name,IP_address,tags,create_access_ID,Status_ID) ...
方案1:SET TRANSACTION ISOLATION LEVEL SERIALIZABLE; BEGIN TRANSACTION; IF EXISTS (SELECT 1 FROM dbo.table WHERE PK = @PK) BEGIN UPDATE ... END ELSE BEGI
SQL Copy -- check the update SELECT x.query(' //ProductDescription/Features') FROM T; GO I. Inserting based on an if condition statementIn the following example, an IF condition is specified as part of Expression1 in the insert XML DML statement. If the condition is True, an attribute...
Specifies the number of rows in a batch. Each batch is copied to the server as one transaction. If this fails, SQL Server commits or rolls back the transaction for every batch. By default, all data in the specified data file is one batch. For information about performance considerations, ...