Update statement is used to update rows in existing tables which is in your own schema or if you have update privilege on them. For example to raise the salary by Rs.500 of employee number 104. You can give the following statement. update emp set sal=sal+500 where empno = 104; In th...
Merge用法:Oracle 10g中对Merge语句的增强 在Oracle 10g之前,merge语句支持匹配更新和不匹配插入2种简单的用法,在10g中Oracle对merge语句做了增强,增加了条件选项和DELETE操作。下面我通过一个demo来简单介绍一下10g中merge的增强和10g前merge的用法。 参考Oracle 的SQL Reference,大家可以看到Merge Statement的语法如下:...
其实呢,merge into部分的update和update也没啥不同的,不同的地方在于使用merge into后执行计划变了。 merge方法是最简洁,效率最高的方式,在大数据量更新时优先使用这种方式。 1. 基本语法 merge into test1 using test2 on (test1.id = test2.id) when matched then update set test1.name = nvl2(test1.na...
在上面例子中, MERGE语句影响到是产品id为1502, 1601和1666的行. 它们的产品名字和种 类被更新为表newproducts中的值. 下面例子省略UPDATE子句, 把表NEWPRODUCTS中新的PRODUCT_ID插入到表PRODUCTS中, 对于在两个表中能够匹配上PRODUCT_ID的数据不作任何处理. 从这个例子你能看到PRODUCT_ID=1700的行被插入到表PROD...
使用MERGE语句选择行从一个或多个源更新或插入一个表或视图。您可以指定条件来决定是否更新或插入到目标表或视图。 This statement is a convenient way to combine multiple operations. It lets you avoid multipleINSERT,UPDATE, andDELETEDML statements. ...
原来一直没注意,merge是可以支持delete,只不过必须的是on条件满足,也就是要求系统支持逻辑删除,而非物理删除。 Using the DELETE Clause with MERGE Statements You may want to cleanse tables while populating or updating them. To do this, you may want to consider using theDELETEclause in aMERGEstatement,...
Update set …. When not matched then Insert values… 以上是merge的基本语法,其中alias是为表或者查询写的别名 如果你看着空洞的语法觉得头很痛,看下面的例子吧 首先我们创建两个表 create table test1(id int,name varchar(20)); create table test2(id int,name varchar(20)) ...
the human resources manager decides that employees with a salary of $8000 or less should receive a bonus. Those who have not made sales get a bonus of 1% of their salary. Those who already made sales get an increase in their bonus equal to 1% of their salary. The MERGE statement impleme...
参考Oracle 的SQL Reference,大家可以看到Merge Statement的语法如下: MERGE [hint] INTO [schema .] table [t_alias] USING [schema .] { table | view | subquery } [t_alias] ON ( condition ) WHEN MATCHED THEN merge_update_clause WHEN NOT MATCHED THEN merge_insert_clause; ...
3. DML: MERGE 3.1 Overview of DML Statements The five DML statements available in Oracle are INSERT, UPDATE, DELETE, MERGE and TRUNCATE. The first three are somewhatexplanatory. MERGE may not be. A MERGE statement will take one row source and merge it into another. And what that means is...