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  • sql基础语句

    mysql workbench

    create table s(`s#` int, `sname` char(8), `grade` int, primary key(`s#`)); #不知道为什么需要 ``, 居然因为是有了 #, 表示了注释,系统有点蒙

    alter table s add address char(10); #这个就不需要``括起来了

    alter table s drop address;

    改正:

    create table s(id_s char(10), name_s char(10), grade_s float, adress char(10),
    primary key(id_s)
    );

    alter table s add age_s int;

    alter table s drop adress;

    insert into s(id_s, name_s, grade_s, age_s)
    values ('001', 'xiaoming', 90, 18),
    ('002', 'xiaogang', 69, 17),
    ('003', 'xiaohua' , 85, 19),
    ('004', 'xiaomi' , 55, 19),
    ('005', 'xiaofa' , 65, 29);

    select *
    from s;

    delete from s
    where (grade_s < 60 or age_s < 12 or age_s > 20) and id_s != '000';

    select *
    from s
    where id_s > 0;

    update s
    set grade_s = grade_s * 1.09 #, id_s = id_s
    where grade_s < 60 and id_s != '0';

    drop table s;

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  • 原文地址:https://www.cnblogs.com/lucky-light/p/13059702.html
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