以下：citeulike是数据库名，user_article是table名

create database citeulike;

create table user_article(user varchar(32), article varchar(12), tag varchar(40));

load data local infile 'path\\data.txt' into table user_article fields terminated by ',';

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删除列表：

delete from user_article；删除表里的内容，表仍在，表头不变

drop table user_article;

drop database citeulike;

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更改表项类型

用到timestamp类型，如果直接用timestamp类型，它默认default current_timestamp on update current_timestamp: 默认值是当前时间，并且该行其它项发生修改时自动更新时间

default current_timestamp:默认值是当前时间，不会自动更新时间

default 0/null：默认值是0/null

default 0/null on update current_timestamp:默认值是0/null，自动更新

on update current_timestamp:没写默认值，通常默认0

想把post_time的类型从current_timestamp on update current_timestamp改成default 0:

alter table user_article change post_time post_time timestamp default 0;

（改成default null显示错误：invalid default value for 'post_time'）

在表里添加字段：

alter table article_abstract add title mediumtext;

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导出数据时

select * from user_article into outfile 'path\output.txt' fields terminated by '\t' lines terminated by '\r\n'; 显示：mysql server is running with the --secure-file-priv option so it cannot execute this statement