第 51 章 DML (Data Manipulation Language)
目录
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51.1. INSERT
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51.1.1. INSERT INTO ... SELECT
51.1.2. INSERT IGNORE
51.1.3. INSERT...ON DUPLICATE KEY UPDATE
51.2. REPLACE
51.3. DELETE
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51.3.1. 删除重复数据
SELECT - retrieve data from the a database INSERT - insert data into a table UPDATE - updates existing data within a table DELETE - deletes all records from a table, the space for the records remain CALL - call a PL/SQL or Java subprogram EXPLAIN PLAN - explain access path to data LOCK TABLE - control concurrency
51.1. INSERT
51.1.1. INSERT INTO ... SELECT
SET @OLDTMP_SQL_MODE=@@SQL_MODE, SQL_MODE=''; DELIMITER // CREATE TRIGGER `members_mobile_insert` BEFORE INSERT ON `members_mobile` FOR EACH ROW BEGIN insert into members_location(id,province,city) select NEW.id,mobile_location.province,mobile_location.city from mobile_location where mobile_location.id = md5(LEFT(NEW.number, 7)); END// DELIMITER ; SET SQL_MODE=@OLDTMP_SQL_MODE;
51.1.2. INSERT IGNORE
INSERT IGNORE 与INSERT INTO的区别就是INSERT IGNORE会忽略数据库中已经存在 的数据，如果数据库没有数据，就插入新的数据，如果有数据的话就跳过这条数据。
insert ignore into table(name) select name from table2
51.1.3. INSERT...ON DUPLICATE KEY UPDATE
create table foo (id serial primary key, u int, unique key (u)); insert into foo (u) values (10); insert into foo (u) values (10) on duplicate key update u = 20; mysql> select * from foo; +----+------+ | id | u | +----+------+ | 1 | 20 | +----+------+
DROP TRIGGER IF EXISTS `cms`.`jc_content_BEFORE_DELETE`;
DELIMITER $$
USE `cms`$$
CREATE DEFINER=`5kwords`@`%` TRIGGER `jc_content_BEFORE_DELETE` BEFORE DELETE ON `jc_content`
FOR EACH ROW BEGIN
insert into `cms`.elasticsearch_trash(id) values(OLD.content_id) on duplicate key update ctime = now();
insert into `cms`.trash(id,`type`, site_id) values(OLD.content_id, "delete", OLD.site_id) on duplicate key update `type`="delete", ctime = now();
END$$
DELIMITER ;
原文出处：Netkiller 系列 手札
本文作者：陈景峯
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