显示账户及日期时间:
select USER(),now();
USER() | now() |
root@localhost | 2020-04-03 08:16:35 |
显示版本及日期:
select version(),current_date();
version() | current_date() |
8.0.17 | 2020-04-03 |
进行简单运算:
select (20+5)*4;
select (20+5)*4,sin(pi()/3);
select (20+5)*4 as Result ,sin(pi()/3);
Result | sin(pi()/3) |
100 | 0.8660254037844386 |
创建一个数据库并显示当前数据库:
create database lianxi;
show databases;
Database |
information_schema |
lianxi |
mydatabase |
mysql |
performance_schema |
delete from tbname order by id desc limit n
首先倒序,然后n条,最后删除