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题解 | #将所有to_date为9999-01-01的全部更新为NULL#

update titles_test set to_date=null,from_date='2001-01-01'where to_date='9999-01-01'update table_name set column_name="value" where column=&...

Sqlite

2021-09-27

0 305

题解 | #在last_update后面新增加一列名字为create_date#

delete from titles_test where not id in(select id from titles_test group by emp_no order by id asc)不知道为什么这样就通过了，先以emp_no 分组，按id升序排序，然后删除掉其中id不等于这些最小值...

Mysql

2021-09-27

0 255

题解 | #在last_update后面新增加一列名字为create_date#

create trigger audit_log before insert on employees_testfor each rowbegin insert into audit (emp_no,name) values(new.id,new.name);end;创建触发器语法：creat...

Mysql

2021-09-27

0 431

题解 | #在last_update后面新增加一列名字为create_date#

alter table actor add column create_date datetime not null default"2020-10-01 00:00:00" after last_update在‘last_update’后追加一列，用‘after’指明所要追加的...

Mysql

2021-09-27

0 303

题解 | #针对上面的salaries表emp_no字段创建索引idx_emp_no#

select * from salaries force index (idx_emp_no) where emp_no = 10005强制使用索引 forceindex（“index_name”）select * from table_name force index（“index_name”）w...

Mysql

2021-09-26

0 250

题解 | #针对actor表创建视图actor_name_view#

create view actor_name_view as select first_name as first_name_v,last_name as last_name_v from actor创建视图语法：create view 'view_name' as select 'column1'...

Mysql

2021-09-26

0 311

题解 | #对first_name创建唯一索引uniq_idx_firstname#

Mysql 创建索引的方法：alter table actor add unique uniq_idx_firstname(first_name);alter table actor add index idx_lastname(last_name); sqllite创建索引方法：create u...

Mysql

2021-09-26

0 316

题解 | #创建一个actor_name表#

drop table if exists actor_name;create table actor_name ( first_name varchar(45) not null comment'名字', last_name varchar(45) not null comment'姓氏...

Mysql

2021-09-26

0 260

题解 | #批量插入数据#

insert ignore into actor(actor_id,first_name,last_name,last_update) values(1,'PENELOPE','GUINESS','2006-02-15 12:34:33'),(2,'NICK','WAHLBERG','2006-02...

Mysql

2021-09-26

0 257

题解 | #创建一个actor表，包含如下列信息#

insert into actor values(1,'PENELOPE','GUINESS',"2006-02-15 12:34:33");insert into actor values(2,'NICK','WAHLBERG',"2006-02-15 12:34:3...

Mysql

2021-09-26

0 230