开始
1.show databases;
2.show tables;
框架
SELECT column1, column2, ...
FROM table_name
WHERE condition
GROUP BY column_name
HAVING condition
ORDER BY column_name
LIMIT number;
SELECT
:用于选择要检索的列。FROM
:指定要从中检索数据的表。WHERE
:可选,用于指定条件,过滤返回的行。GROUP BY
:可选,用于将结果集按一个或多个列分组。HAVING
:可选,类似于WHERE
,但是用于过滤分组后的行。ORDER BY
:可选,用于指定结果集的排序顺序。LIMIT
:可选,用于限制返回的行数。