MySQL - 집계함수

집계함수

{
    CREATE TABLE myRecode (
        recodeID int(10) unsigned auto_increment,
        memberID int(10) unsigned,
        javascript tinyint unsigned NOT NULL,
        html tinyint NOT NULL, 
        css tinyint NOT NULL, 
        mysql tinyint NOT NULL, 
        react tinyint NOT NULL, 
        PRIMARY KEY (recodeID)
    ) charset=utf8;
    
    INSERT INTO myRecode(memberID, javascript, html, css, mysql, react) VALUE(1, 60, 30, 10, 20, 20);
    INSERT INTO myRecode(memberID, javascript, html, css, mysql, react) VALUE(2, 50, 40, 20, 30, 30);
    INSERT INTO myRecode(memberID, javascript, html, css, mysql, react) VALUE(3, 40, 50, 40, 40, 50);
    INSERT INTO myRecode(memberID, javascript, html, css, mysql, react) VALUE(4, 30, 60, 50, 10, 40);
    INSERT INTO myRecode(memberID, javascript, html, css, mysql, react) VALUE(5, 20, 70, 80, 50, 60);
    INSERT INTO myRecode(memberID, javascript, html, css, mysql, react) VALUE(6, 10, 80, 70, 60, 90);
    INSERT INTO myRecode(memberID, javascript, html, css, mysql, react) VALUE(7, 80, 10, 60, 70, 70);
    INSERT INTO myRecode(memberID, javascript, html, css, mysql, react) VALUE(8, 70, 20, 50, 80, 60);
    INSERT INTO myRecode(memberID, javascript, html, css, mysql, react) VALUE(9, 90, 30, 40, 90, 90);
    INSERT INTO myRecode(memberID, javascript,  html, css, mysql, react) VALUE(10, 10, 40, 30, 90, 30);
}

{
    집계함수의 종류
    SELECT count(javascript) FROM myRecode;
    SELECT sum(javascript) FROM myRecode;
    SELECT avg(javascript) FROM myRecode;    (평균)
    SELECT max(javascript) FROM myRecode;    (최고)
    SELECT min(javascript) FROM myRecode;    (최저)
}