通过MERGE语句,根据一张表或子查询的连接条件对另外一张表进行查询,连接条件匹配上的进行UPDATE,无法匹配的执行INSERT。这个语法仅需要一次全表扫描就完成了全部工作,执行效率要高于INSERT+UPDATE。 语法: MERGE INTO [your table-name] [rename your table here] USING ( [write your query here] )[rename your ...
• 未使用索引合并时,MySQL利用索引idx_a获取到满足条件a=1的所有主键id,根据主键id进行回表查询到相关记录,随后再使用条件b='C'对这些记录进行判断,获取最终查询结果。 mysql> explain SELECT/*+ NO_INDEX_MERGE(T idx_a,idx_b)*/* FROM T WHERE a=1AND b='C';+---+---+---+---+---+---...
pg数据库merge语句改写为mysql Oracle中merge Into的用法 使用场景 在操作数据库时,数据存在的情况下,进行update操作;不存在的情况下,进行insert操作;在Oracle数据库中,能够使用merge into来实现。 基本语法 merge into table_name alias1 -- 目标表 可以用别名表示 using (table|view|sub_query) alias2 -- 数据...
If all columns used in the query are covered by the used indexes, full table rows are not retrieved (EXPLAIN output contains Using index in Extra field in this case). Here is an example of such a query: SELECT COUNT(*) FROM t1 WHERE key1 = 1 AND key2 = 1; If the used indexes...
mysql>insertintopayment_allvalues(3,'2006-03-31',112200); Query OK,1row affected (0.00sec)mysql>select*frompayment_all;+---+---+---+|country_id|payment_date|amount|+---+---+---+|1|2006-05-0100:00:00|100000.00||2|2006-08-1500:00:00|150000.00||1|2007-02-2000:00:00|350000....
August 18, 2015MySQLAnvesh Patel,database,database research and development,MySQL,MySQL Command,MySQL Database Administrator,MySQL Database Designing,MySQL Database Programming,MySQL Error,MySQL Performance Tunning,MySQL Query,MySQL Tips and Tricks,ON DUPLICATE KEY UPDATE...
1 row in set (0.00 sec) mysql> insert into `200702` (`domain`, `2nd_domain`, `tld`, `query_ns1`, `query_ns2`, `report_date`) values (dnspod.com, dnspod, com, 1000, 2000, 2007-02-04) ON DUPLICATE KEY UPDATE `query_ns1` = `query_ns1` + 1000, `query_ns2` = `query_ns2...
mysql tables in use 3, locked 3 LOCK WAIT 5 lock struct(s), heap size 1136, 4 row lock(s) MySQL thread id 2289, OS thread handle 123145606135808, query id 1725930 localhost 127.0.0.1 root updating UPDATE `lists` SET `updated_at` = '2019-04-20 17:17:57.752797' WHERE (`interval` ...
一下这个点 merge语句具有按条件获取要更新或插入到表中的数据行,然后从一个或多个源头对表进行更新或者向表中插入行两方面的能力...,它最经常用在数据仓库中来移动大量的数据,这个语句提供的一个很大的附加值在于你可以很方便的把多个操作结合成一个 Merge的语法: Merge Into 别名 USING...
This topic provides reference information about migrating from Microsoft SQL Server 2019’s MERGE statement to equivalent functionality in Amazon Aurora MySQL. You can understand the key differences and similarities between SQL Server’s MERGE capabiliti