1 lesson01数据库增删查改 2 #备注:潭州课堂网页,视频没有了 3 4 5 #视频1 6 7 安装:sudo apt-get install mysql-server 8 进入mysql:mysql -uroot -pqwe123 9 10 关闭sql:service mysql stop 11 开启sql: service mysql start 12 13 #视频4 14 显示所有数据库:show databases; 15 创建库:create database[if not exists]db_name; //重复创建会报错,所以加上if not exists 16 删除库:drop database [if exists] db_name; //如果不知道数据库是否存在,记得加if exists 17 切换当前库:use db_name; 18 19 显示表:show tables; 20 创建表:create table tbl_name(create_definition,...) 21 显示创建表的信息:show create table tb_name; 22 删除表:drop table tb_name; 23 显示表属性:desc student; 24 25 注意事项: 26 语句结束符;或\G 27 大小写:不严格区分大小写,默认大写为程序代码,小写为程序员写的代码 28 类型:强制数据类型,任何数据都有自己的类型 29 逗号:创建表最后一列不需要逗号 30 31 32 33 #xshell 中练习 34 35 36 #视频5 增删改查 37 指定列插入:INSERT INTO tb_name(col_names) VALUES (col_values) 38 全列插入:INSERT INTO tb_name VALUES (all_values); 39 多行插入:INSERT INTO tb_name(col_names) VALUES(value_1),(value_2),..., 40 41 区别 42 指定列插入某列某值,单行操作 43 全列插入:需要给所有列赋值,单行操作 44 多行插入:插入多行数据 45 46 insert into test(id) values('hello') 47 insert into test(id,name) values(1,'句号'); 48 select *from test; 49 50 z指定列查询:select col_names from tb_name; 51 全列查询:select *from tb_name; 52 带条件的查询:select col_names from tb_name where conditions; 53 54 55 修改表中所有数据:update tb_name set field_1=value_1 56 修改表中指定的数据:update tb_name set field_1=value_1 where conditions; 57 58 注意:一定要写where条件,不然会修改表中全部数据 59 60 删除表中所有数据:delete from tb_name; 61 删除表中满足条件的数据:delete from tb_name where conditions; 62 注意:一定要写where条件,不然会删除表中全部数据 63 64 65 看ppt 66 #在xhell 练习mysql 67 mysql -uroot -pqwe123 68 show databases; 69 create database juhao; 70 use juhao; 71 create table student (id int,name varchar(20)); 72 desc student; 73 show tables; 74 insert into student (id,name) values(1,'dabu'); 75 select *from student; 76 insert into student values(2,'da'), (3,'zz'), (4,'dd'), (5,'dd'); 77 select *from student where name='dd'; 78 update student set name='new_zz' where id=3; 79 delete from student where id=2; 80 81 82 83 creat table tb2( 84 id INT, 85 name VARCHAR(20), 86 sex CHAR(4), 87 price DOUBLE(4,2), 88 detail TEXT, 89 datae DATATIME, 90 ping ENUM('好评','差评') 91 ); 92 93 insert intotb2 value(1,'裤子','男',20.0,'这条裤子超级好!',now(),'好评'); 94 95 96 97 ------------------------------------------------------ 98 #作业: 99 1.建一张学生表 包含(id,姓名,年龄,性别)。 100 1.查看表结构 101 2.增加四条数据 102 3.查询所有数据 103 4.删除id =3的数据, 104 5.将性别为女的,修改为男 105 106 //mysql代码 107 create table student02(id int,name varchar(20),age int,sex enum('man','woman','weizhi')); 108 109 desc student02; 110 111 insert into student02 values 112 113 (1,'dabu',18,'man') 114 (2,'xiaoli',18,'woman') 115 (3,'zhaosi',18,'man') 116 (4,'wanger',18,'man') 117 118 delete from student02 where id=3; 119 120 mysql> update student02 set sex='man' where sex='woman'; 121 122 123 -------------------------------------------- 124 #1 125 pyvip@Vip:~$ mysql -uroot -pqwe123 126 127 128 #2 129 mysql> show databases; 130 +--------------------+ 131 | Database | 132 +--------------------+ 133 | information_schema | 134 | 05test | 135 | juhao | 136 | lianjia_db | 137 | mydb | 138 | mysql | 139 | performance_schema | 140 | sys | 141 | tudo27 | 142 +--------------------+ 143 144 #3 145 mysql> use juhao; 146 147 148 #4 149 mysql> show tables; 150 +-----------------+ 151 | Tables_in_juhao | 152 +-----------------+ 153 | student | 154 | student02 | 155 +-----------------+ 156 157 158 #5 159 mysql> select *from student02; 160 +------+--------+------+------+ 161 | id | name | age | sex | 162 +------+--------+------+------+ 163 | 1 | dabu | 18 | man | 164 | 2 | xiaoli | 18 | man | 165 | 4 | wanger | 18 | man | 166 +------+--------+------+------+ 167 3 rows in set (0.00 sec) 168 169 #6 170 mysql> desc student02; 171 +-------+------------------------------+------+-----+---------+-------+ 172 | Field | Type | Null | Key | Default | Extra | 173 +-------+------------------------------+------+-----+---------+-------+ 174 | id | int(11) | YES | | NULL | | 175 | name | varchar(20) | YES | | NULL | | 176 | age | int(11) | YES | | NULL | | 177 | sex | enum('man','woman','weizhi') | YES | | NULL | | 178 +-------+------------------------------+------+-----+---------+-------+ 179 4 rows in set (0.00 sec)
1-数据库增删查改
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