标签：对表 name 23 mysql 数据库 people 1989 birthday MySQL
本站文章均为 李华明Himi 原创,转载务必在明显处注明
通过上一篇的介绍，大家可以创建自己的数据库和表以及插入表中数据等等，本章继续介绍更多的数据库的相关操作；
1. 查看所有表单数据：（这里我直接使用上一篇创建的himiDB数据库与其中的people表进行讲解，还不太熟悉的请移步到上一篇的博文） 步骤：（获取）显示所有已存在的数据库->使用himidb数据库->（获取）显示所有表->（获取）显示所有表内的数据
mysql> show databases;
+ --------------------+
| Database |
+ --------------------+
| information_schema |
| himiDB |
| mysql |
| performance_schema |
| test |
+ --------------------+
5 rows in set (0.00 sec)
mysql> use himidb;
Database changed
mysql> show tables;
+ ------------------+
| Tables_in_himidb |
+ ------------------+
| people |
+ ------------------+
1 row in set (0.00 sec)
mysql> select * from people;
+ ------------+------+----------+------+-----------+------------+
| name | mz | city | sex | birthday | deathday |
+ ------------+------+----------+------+-----------+------------+
| himi | h | beijing | m | 1989-9-23 | NULL |
| himi | h | beijing | m | 1989-9-23 | NULL |
| himi3 | h | beijing | m | 1989-9-23 | NULL |
| insertHimi | h | Anhui | m | 1989-9-23 | NULL |
| tommy | m | chaoxian | w | 19890823 | 2100-10-10 |
+ ------------+------+----------+------+-----------+------------+
5 rows in set (0.00 sec)
|
2. 假设我们修改people中的tommy 的生日为 1990-1-1日：
2.1：第一种方式可以通过txt进行，假设我们已经有一个txt存储了所有表内数据，并且tommy的生日在txt中已经是最新的了，那么我们就可以直接如下来进行更改（注意这种方式是删除以前所有表元素直接进行重新添加的操作！如果你没有之前这些数据就不要使用此方式）
mysql> DELETE FROM people;
mysql> LOAD DATA LOCAL INFILE '/xxx/xxx/people.txt' INTO TABLE people;
|
2.2：使用UPDATE进行指向性修改；
语句形式： update xx(表名) set xx(item名) =’xxx新value’ where xx(item索引) =”where中item索引的对应value”;
示例：
mysql> update people set birthday = '1990-1-1' where name = 'tommy' ;
Query OK, 1 row affected (0.11 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from people;
+ ------------+------+----------+------+-----------+------------+
| name | mz | city | sex | birthday | deathday |
+ ------------+------+----------+------+-----------+------------+
| himi | h | beijing | m | 1989-9-23 | NULL |
| himi | h | beijing | m | 1989-9-23 | NULL |
| himi3 | h | beijing | m | 1989-9-23 | NULL |
| insertHimi | h | Anhui | m | 1989-9-23 | NULL |
| tommy | m | chaoxian | w | 1990-1-1 | 2100-10-10 |
+ ------------+------+----------+------+-----------+------------+
5 rows in set (0.00 sec)
|
3.查看特定条件所有数据：
mysql> select * from people where name = 'himi' ;
+ ------+------+---------+------+-----------+----------+
| name | mz | city | sex | birthday | deathday |
+ ------+------+---------+------+-----------+----------+
| himi | h | beijing | m | 1989-9-23 | NULL |
| himi | h | beijing | m | 1989-9-23 | NULL |
+ ------+------+---------+------+-----------+----------+
2 rows in set (0.08 sec)
|
通过以上可以看出是在 select *from xx 后加入指向，比较容易理解；
继续查看哪些是大于1990年之前的额people：
mysql> select * from people where birthday < '1990-1-1' ;
+ ------------+------+---------+------+-----------+----------+
| name | mz | city | sex | birthday | deathday |
+ ------------+------+---------+------+-----------+----------+
| himi | h | beijing | m | 1989-9-23 | NULL |
| himi | h | beijing | m | 1989-9-23 | NULL |
| himi3 | h | beijing | m | 1989-9-23 | NULL |
| insertHimi | h | Anhui | m | 1989-9-23 | NULL |
+ ------------+------+---------+------+-----------+----------+
4 rows in set (0.01 sec)
|
继续查看表中有几个woman：
mysql> select * from people where sex = "w" ;
+ -------+------+----------+------+----------+------------+
| name | mz | city | sex | birthday | deathday |
+ -------+------+----------+------+----------+------------+
| tommy | m | chaoxian | w | 1990-1-1 | 2100-10-10 |
+ -------+------+----------+------+----------+------------+
1 row in set (0.00 sec)
|
继续查看表中既是woman又是在1990年以前的：（AND）
mysql> select * from people where sex = "m" and birthday < '1990-1-1' ;
+ ------------+------+---------+------+-----------+----------+
| name | mz | city | sex | birthday | deathday |
+ ------------+------+---------+------+-----------+----------+
| himi | h | beijing | m | 1989-9-23 | NULL |
| himi | h | beijing | m | 1989-9-23 | NULL |
| himi3 | h | beijing | m | 1989-9-23 | NULL |
| insertHimi | h | Anhui | m | 1989-9-23 | NULL |
+ ------------+------+---------+------+-----------+----------+
4 rows in set (0.00 sec)
|
继续查看表中叫tommy 或者 是beijing地区的：(OR)
mysql> select * from people where city= 'beijing' or birthday < '1990-1-1' ;
+ ------------+------+---------+------+-----------+----------+
| name | mz | city | sex | birthday | deathday |
+ ------------+------+---------+------+-----------+----------+
| himi | h | beijing | m | 1989-9-23 | NULL |
| himi | h | beijing | m | 1989-9-23 | NULL |
| himi3 | h | beijing | m | 1989-9-23 | NULL |
| insertHimi | h | Anhui | m | 1989-9-23 | NULL |
+ ------------+------+---------+------+-----------+----------+
4 rows in set (0.00 sec)
|
AND和OR可以混用，但AND比OR具有更高的优先级。如果使用两个操作符，使用圆括号进行分组~如下：
mysql> select * from people where (city= 'beijing' and sex= 'w' ) or (city = 'chaoxian' and sex = 'w' );
+ -------+------+----------+------+----------+------------+
| name | mz | city | sex | birthday | deathday |
+ -------+------+----------+------+----------+------------+
| tommy | m | chaoxian | w | 1990-1-1 | 2100-10-10 |
+ -------+------+----------+------+----------+------------+
1 row in set (0.00 sec)
|
4.查看所有数据的特定条件：
假如我们需要查看所有人的性别 和名字：
mysql> select name ,birthday from people;
+ ------------+-----------+
| name | birthday |
+ ------------+-----------+
| himi | 1989-9-23 |
| himi | 1989-9-23 |
| himi3 | 1989-9-23 |
| insertHimi | 1989-9-23 |
| tommy | 1990-1-1 |
+ ------------+-----------+
5 rows in set (0.00 sec)
|
从上面的名字来看，发现了重复的名字，那么如果只想让同一名字只显示一个，可以使用 distinct 关键字；如下：
mysql> select distinct name from people;
+ ------------+
| name |
+ ------------+
| himi |
| himi3 |
| insertHimi |
| tommy |
+ ------------+
4 rows in set (0.00 sec)
|
来个复杂点的：使用一个WHERE子句结合行选择与列选择
mysql> select name from people where city= 'chaoxian' and birthday = '1990-1-1' ;+ -------+
| name |
+ -------+
| tommy |
+ -------+
1 row in set (0.00 sec)
|
选择出的列根据生日进行排序显示(提前Himi这里又往表中添加了很多人)
mysql> select birthday from people order by birthday;
+ -----------+
| birthday |
+ -----------+
| 1989-9-23 |
| 1989-9-23 |
| 1989-9-23 |
| 1989-9-23 |
| 1990-1-1 |
| 1991-2-3 |
| 1992-5-3 |
+ -----------+
7 rows in set (0.00 sec)
|
选择出的列根据名字降序进行排序显示：
mysql> select name from people order by name desc ;
+ ------------+
| name |
+ ------------+
| xiao |
| tommy |
| insertHimi |
| himi3 |
| himi |
| himi |
| chinle |
+ ------------+
7 rows in set (0.00 sec)
|
5. 日起计算；
MySQL提供了几个函数，可以用来计算日期，例如，计算年龄或提取日期部分:
YEAR()提取日期的年部分，
RIGHT(x,y)提取 x 日期的MM-DD (日历年) 部分的最右面y个字符。
mysql> select name ,birthday,curdate(),( year (curdate())- year (birthday))- ( right (curdate(),5)< right (birthday,5)) from people;
+ ------------+-----------+------------+--------------------------------------------------------------------------+
| name | birthday | curdate() | ( year (curdate())- year (birthday))- ( right (curdate(),5)< right (birthday,5)) |
+ ------------+-----------+------------+--------------------------------------------------------------------------+
| himi | 1989-9-23 | 2012-04-17 | 23 |
| himi | 1989-9-23 | 2012-04-17 | 23 |
| himi3 | 1989-9-23 | 2012-04-17 | 23 |
| insertHimi | 1989-9-23 | 2012-04-17 | 23 |
| tommy | 1990-1-1 | 2012-04-17 | 22 |
| xiao | 1991-2-3 | 2012-04-17 | 20 |
| chinle | 1992-5-3 | 2012-04-17 | 19 |
+ ------------+-----------+------------+--------------------------------------------------------------------------+
7 rows in set (0.00 sec)
|
下面我们算下死亡时间和当前时间的差值，其中我们排除deathday为NULL的人。
mysql> select name ,deathday,curdate(),( year (curdate())- year (deathday))- ( right (curdate(),5)< right (deathday,5)) from people where deathday is not null ;
+ --------+------------+------------+--------------------------------------------------------------------------+
| name | deathday | curdate() | ( year (curdate())- year (deathday))- ( right (curdate(),5)< right (deathday,5)) |
+ --------+------------+------------+--------------------------------------------------------------------------+
| tommy | 2100-10-10 | 2012-04-17 | -89 |
| xiao | 1994-1-1 | 2012-04-17 | 17 |
| chinle | 1994-1-1 | 2012-04-17 | 17 |
+ --------+------------+------------+--------------------------------------------------------------------------+
3 rows in set (0.00 sec)
|
MySQL提供几个日期部分的提取函数，例如YEAR( )、MONTH( )和DAYOFMONTH( )。在这里MONTH()是适合的函数。为了看它怎样工作，运行一个简单的查询:
mysql> select name ,birthday, year (birthday), month (birthday) ,dayofmonth(birthday) from people;
+ ------------+-----------+----------------+-----------------+----------------------+
| name | birthday | year (birthday) | month (birthday) | dayofmonth(birthday) |
+ ------------+-----------+----------------+-----------------+----------------------+
| himi | 1989-9-23 | 1989 | 9 | 23 |
| himi | 1989-9-23 | 1989 | 9 | 23 |
| himi3 | 1989-9-23 | 1989 | 9 | 23 |
| insertHimi | 1989-9-23 | 1989 | 9 | 23 |
| tommy | 1990-1-1 | 1990 | 1 | 1 |
| xiao | 1991-2-3 | 1991 | 2 | 3 |
| chinle | 1992-5-3 | 1992 | 5 | 3 |
+ ------------+-----------+----------------+-----------------+----------------------+
7 rows in set (0.00 sec)
|
练习：找到一个下个月是几月份：
mysql> select name ,birthday, month (birthday)+1 from people;
+ ------------+-----------+-------------------+
| name | birthday | month (birthday)+1 |
+ ------------+-----------+-------------------+
| himi | 1989-9-23 | 10 |
| himi | 1989-9-23 | 10 |
| himi3 | 1989-9-23 | 10 |
| insertHimi | 1989-9-23 | 10 |
| tommy | 1990-1-1 | 2 |
| xiao | 1991-2-3 | 3 |
| chinle | 1992-5-3 | 6 |
+ ------------+-----------+-------------------+
7 rows in set (0.00 sec)
|
标签：对表,
name,
23,
mysql,
数据库,
people,
1989,
birthday,
MySQL
From： https://blog.51cto.com/xiaominghimi/5886192