Tag:average age

  • Multi table join query and sub query of MySQL

    Time:2022-2-12

    1. Preliminary preparation #Build table create table department( id int, name varchar(20) ); create table employee( id int, name varchar(20), sex enum(‘male’,’female’), age int, dep_id int ); #Insert data insert into department values (200, ‘technology’), (201, ‘human resources’), (202, ‘sales’), (203, ‘operation’); insert into employee(id,name,sex,age,dep_id) values (1,’cai’,’male’,18,200), (2,’liu’,’female’,48,201), (3,’ling’,’male’,38,201), (4,’liangliang’,’female’,28,202), (5,’acai’,’male’,18,200), (6,’bao’,’female’,18,204) ; 2. Connected […]

  • More than half of the enterprise workstations cannot run Windows 11; Python 3.10.0 officially released; Android 12 releases Sina weekly

    Time:2021-10-25

    40s News Express The Municipal Administration of supervision has imposed administrative penalties on the “one out of two” monopoly of meituan   thirty-four point four two   Hundred million Apple   NFC   Chips face EU antitrust investigation or open to rivals Telegram   On Facebook   7000 new on the day of downtime   […]

  • MySQL Basics

    Time:2021-10-7

    MySQL table query statement DQL: query statement Sort query Syntax: order by clause Sort by: ASC: ascending, default Desc: descending order. be careful: If there are multiple sorting conditions, the second condition will be judged only when the condition values of the current edge are the same SELECT * from userinfo ORDER BY age ASC,id […]

  • Basic knowledge of MySQL

    Time:2021-1-17

    MySQL table query statement DQL: query statement Sort query Syntax: order by clause Sort by: ASC: ascending order, default Desc: descending order. be careful: If there are multiple sorting conditions, the second condition will be judged only when the condition values of the current edge are the same SELECT * from userinfo ORDER BY age […]

  • MySQL filter criteria, aggregate grouping, connection query

    Time:2020-7-7

    Screening criteria Comparison operator Equal to: = (note! Not = =) Not equal to:! = or < > Greater than: > Greater than or equal to: >= Less than:< Less than or equal to:<= IS NULL IS NOT NULL Logical operator And: and Or: or Not: not Other operations Order by Positive sequence: ASC Reverse: […]