MySQL tutorial: mysql inner, left, right, full join explained
Mysq joins two table query, roughly divided into inner join, full join (outer join), right join, and left join....
MySQL tutorial: mysql round() function
MySQL ROUND() is a mathematical function that rounds Numbers to a specified number of decimal places....
MySQL tutorial: mysql group by count percentage
Mysql group by count percentage, you can count the proportion of certain conditions in the total amount of data....
MySQL tutorial: mysql concat() function
The MySQL CONCAT function accepts one or more string parameters and concatenates them into a string....