MairDB 查詢表(四)

第一部分 基本SELECT

1.1 檢索單列

> SELECT 列名 FROMM 表名;

1.2 檢索多列

> SELECT 列名1, 列名2, 列名3...     FROM 表名;

1.3 檢索全部的列

> SELECT * FROM 表名;

1.4 去除重複列DISTINCT: 去除重複行

> SELECT DISTINCT 列名 FROM 表名;

1.5 限制檢索數

> SELECT 列名 FROM 表 LIMIT 4;

1.6 基本排序

升序: 默認 <ASC>(ascending order); 降序:**DESC**(descending order); > SELECT * FROM books ORDER BY book_id;     +---------+------------------+------------------+------------------+-------------+----------+------+ | book_id | book_name        | book_author_name | publication_date | description | classify | c    | +---------+------------------+------------------+------------------+-------------+----------+------+ |       1 | 跟我學MariaDB    | NULL             | 2016-12-03       | NULL        | 18       | NULL | |       2 | NodeJS           | NULL             | 2016-12-02       | NULL        | 18       | NULL | |       3 | HTTP權威指南     | NULL             | 2002-01-01       | NULL        | 18       | NULL |   > SELECT * FROM books ORDER BY book_id DESC; +---------+------------------+------------------+------------------+-------------+----------+------+ | book_id | book_name        | book_author_name | publication_date | description | classify | c    | +---------+------------------+------------------+------------------+-------------+----------+------+ |      22 | 巨人的隕落       | NULL             | 2016-05-01       | NULL        | 11       | NULL | |      21 | 史記             | NULL             | 1982-11-01       | NULL        | 11       | NULL | |      20 | 國史大綱         | NULL             | 2013-08-01       | NULL        | 11       | NULL | |      19 | 人類簡史         | NULL             | 2014-11-01       | NULL        | 11       | NULL |