Tag：average age
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Multi table join query and sub query of MySQL
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 […]
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More than half of the enterprise workstations cannot run Windows 11; Python 3.10.0 officially released; Android 12 releases Sina weekly
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 […]
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MySQL Basics
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 […]
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Basic knowledge of MySQL
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 […]
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MySQL filter criteria, aggregate grouping, connection query
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: […]