-- 資料庫的操作
-- 連結資料庫
mysql -uroot -p
mysql -uroot -pmysql
-- 退出資料庫
exit/quit/ctrl+d
-- sql語句最後需要有分號;結尾
-- 顯示資料庫版本
select version();
-- 顯示時間
select now();
-- 檢視所有資料庫
show databases;
-- 建立資料庫
-- create database 資料庫名 charset=utf8;
create database python04;
create database python04new charset=utf8;
-- 檢視建立資料庫的語句
-- show crate database ....
show create database python04;
-- 檢視當前使用的資料庫
select database();
-- 使用資料庫
-- use 資料庫的名字
use python04new;
-- 刪除資料庫
-- drop database 資料庫名;
drop database python04;
-- 資料表的操作
-- 檢視當前資料庫中所有表
show tables;
-- 建立表
-- auto_increment表示自動增長
-- not null 表示不能為空
-- primary key 表示主鍵s
-- default 預設值
-- create table 資料表名字 (欄位 型別 約束[, 欄位 型別 約束]);
create table xxxxx(
id int, name varchar(30)
);
create table yyyyy(
id int primary key not null auto_increment,
name varchar(30)
);
create table zzzzz(
id int primary key not null auto_increment,
name varchar(30)
);
-- 檢視錶結構
-- desc 資料表的名字;
desc xxxxx;
-- 建立students表(id、name、age、high、gender、cls_id)
create table students(
id int unsigned not null auto_increment primary key,
name varchar(30),
age tinyint unsigned default 0,
high decimal(5,2),
gender enum("男", "女", "中性", "保密") default "保密",
cls_id int unsigned
);
insert into students values(0, "老王", 18, 188.88, "男", 0);
insert into students values(0, "王小二", 19, 150.12, "女", 1);
insert into students values(0, "李爽", 22, 165.00, "女", 2);
insert into students values(0, "李傑", 60, 158.10, "男", 3);
insert into students values(0, "劉菲菲", 12, 175.50, "女", 4);
insert into students values(0, "小明", 19, 161.30, "男", 0);
insert into students values(0, "李蕾", 16, 158.20, "女", 1);
insert into students values(0, "韓沒滅", 25, 150.00, "男", 2);
insert into students values(0, "傑克", 36, 180.12, "女", 3);
insert into students values(0, "路西", 18, 183.12, "男", 4);
insert into students values(0, "王靜", 12, 196.12, "中性", 1);
insert into students values(0, "王姐", 34, 188.12, "男", 1);
insert into students values(0, "徐開心", 35, 200.12, "女", 2);
insert into students values(0, "江配", 39, 196.12, "", 3);
insert into students values(0, "盛淑星", 26, 162.12, "女", 4);
insert into students values(0, "鄧程飛", 19, 169.12, "男", 5);
insert into students values(0, "江鈴", 18, 175.12, "女", 6);
insert into students values(0, "唐世菊", 13, 190.12, "男", 1);
select * from students;
-- 建立classes表(id、name)
create table classes(
id int unsigned not null auto_increment primary key,
name varchar(30)
gender enum("男", "女", "中性", "保密") default "保密"
);
insert into classes values(0, "python04大神");
select * from classes;
-- 檢視錶的建立語句
-- show create table 表名字;
show create table students;
-- 修改表-新增欄位
-- alter table 表名 add 列名 型別;
alter table students add birthday datetime;
-- 修改表-修改欄位：不重新命名版
-- alter table 表名 modify 列名 型別及約束;
alter table students modify birthday date;
-- 修改表-修改欄位：重新命名版
-- alter table 表名 change 原名 新名 型別及約束;
alter table students change birthday birth date default "2000-01-01";
-- 修改表-刪除欄位
-- alter table 表名 drop 列名;
alter table students drop high;
-- 刪除表
-- drop table 表名;
-- drop database 資料庫;
-- drop table 資料表;
drop table xxxxx;
-- 增刪改查(curd)
-- 增加
-- 全列插入
-- insert [into] 表名 values(...)
-- 主鍵欄位 可以用 0 null default 來佔位
-- 向classes表中插入 一個班級
insert into classes values(0, "菜鳥班");
+--------+-------------------------------------+------+-----+------------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------+-------------------------------------+------+-----+------------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| name | varchar(30) | YES | | NULL | |
| age | tinyint(3) unsigned | YES | | 0 | |
| gender | enum('男','女','中性','保密') | YES | | 保密 | |
| cls_id | int(10) unsigned | YES | | NULL | |
| birth | date | YES | | 2000-01-01 | |
+--------+-------------------------------------+------+-----+------------+----------------+
-- 向students表插入 一個學生資訊
insert into students values(0, "小李飛刀", 20, "女", 1, "1990-01-01");
insert into students values(null, "小李飛刀", 20, "女", 1, "1990-01-01");
insert into students values(default, "小李飛刀", 20, "女", 1, "1990-01-01");
-- 失敗
-- insert into students values(default, "小李飛刀", 20, "第4性別", 1, "1990-02-01");
-- 列舉中 的 下標從1 開始 1---“男” 2--->"女"....
insert into students values(default, "小李飛刀", 20, 1, 1, "1990-02-01");
-- 部分插入
-- insert into 表名(列1,...) values(值1,...)
insert into students (name, gender) values ("小喬", 2);
-- 多行插入
insert into students (name, gender) values ("大喬", 2),("貂蟬", 2);
insert into students values(default, "西施", 20, "女", 1, "1990-01-01"), (default, "王昭君", 20, "女", 1, "1990-01-01");
-- 修改
-- update 表名 set 列1=值1,列2=值2... where 條件;
update students set gender=1; -- 全部都改
update students set gender=1 where name="小李飛刀"; -- 只要name是小李飛刀的 全部的修改
update students set gender=1 where id=3; -- 只要id為3的 進行修改
update students set age=22, gender=1 where id=3; -- 只要id為3的 進行修改
-- 查詢基本使用
-- 查詢所有列
-- select * from 表名;
select * from students;
---定條件查詢
select * from students where name="小李飛刀"; -- 查詢 name為小李飛刀的所有資訊
select * from students where id>3; -- 查詢 name為小李飛刀的所有資訊
-- 查詢指定列
-- select 列1,列2,... from 表名;
select name,gender from students;
-- 可以使用as為列或表指定別名
-- select 欄位[as 別名] , 欄位[as 別名] from 資料表 where ....;
select name as 姓名,gender as 性別 from students;
-- 欄位的順序
select id as 序號, gender as 性別, name as 姓名 from students;
-- 刪除
-- 物理刪除
-- delete from 表名 where 條件
delete from students; -- 整個資料表中的所有資料全部刪除
delete from students where name="小李飛刀";
-- 邏輯刪除
-- 用一個欄位來表示 這條資訊是否已經不能再使用了
-- 給students表新增一個is_delete欄位 bit 型別
alter table students add is_delete bit default 0;
update students set is_delete=1 where id=6;
-- 資料的準備
-- 建立一個資料庫
create database python_test charset=utf8;
-- 使用一個資料庫
use python_test;
-- 顯示使用的當前資料是哪個?
select database();
-- 建立一個資料表
-- students表
create table students(
id int unsigned primary key auto_increment not null,
name varchar(20), --default '',
age tinyint unsigned default 0,
height decimal(5,2),
gender enum('男','女','中性','保密'),-- default '保密',
cls_id int unsigned default 0,
is_delete bit default 0
);
-- classes表
create table classes (
id int unsigned auto_increment primary key not null,
name varchar(30) not null
);
-- 查詢
-- 查詢所有欄位
-- select * from 表名;
select * from students;
select * from classes;
select id, name from classes;
-- 查詢指定欄位
-- select 列1,列2,... from 表名;
select name, age from students;
-- 使用 as 給欄位起別名
-- select 欄位 as 名字.... from 表名;
select name as 姓名, age as 年齡 from students;
-- select 表名.欄位 .... from 表名;
select students.name, students.age from students;
-- 可以通過 as 給表起別名
-- select 別名.欄位 .... from 表名 as 別名;
select students.name, students.age from students;
select s.name, s.age from students as s;
-- 失敗的select students.name, students.age from students as s;
-- 消除重複行
-- distinct 欄位
select distinct gender from students;
-- 條件查詢
-- 比較運算子
-- select .... from 表名 where .....
-- >
-- 查詢大於18歲的資訊
select * from students where age>18;
select id,name,gender from students where age>18;
-- <
-- 查詢小於18歲的資訊
select * from students where age<18;
-- >=
-- <=
-- 查詢小於或者等於18歲的資訊
-- =
-- 查詢年齡為18歲的所有學生的名字
select * from students where age=18;
-- != 或者 <>
-- 邏輯運算子
-- and
-- 18到28之間的所以學生資訊
select * from students where age>18 and age<28;
-- 失敗select * from students where age>18 and <28;
-- 18歲以上的女性
select * from students where age>18 and gender="女";
select * from students where age>18 and gender=2;
-- or
-- 18以上或者身高查過180(包含)以上
select * from students where age>18 or height>=180;
-- not
- 不在 18歲以上的女性 這個範圍內的資訊
-- select * from students where not age>18 and gender=2;
select * from students where not (age>18 and gender=2);
-- 年齡不是小於或者等於18 並且是女性
select * from students where (not age<=18) and gender=2;
-- 模糊查詢
-- like
-- % 替換1個或者多個
-- _ 替換1個
-- 查詢姓名中 以 "小" 開始的名字
select name from students where name="小";
select name from students where name like "小%";
-- 查詢姓名中 有 "小" 所有的名字
select name from students where name like "%小%";
-- 查詢有2個字的名字
select name from students where name like "__";
-- 查詢有3個字的名字
select name from students where name like "__";
-- 查詢至少有2個字的名字
select name from students where name like "__%";
-- rlike 正則
-- 查詢以 周開始的姓名
select name from students where name rlike "^周.*";
-- 查詢以 周開始、倫結尾的姓名
select name from students where name rlike "^周.*倫$";
-- 範圍查詢
-- in (1, 3, 8)表示在一個非連續的範圍內
-- 查詢 年齡為18、34的姓名
select name,age from students where age=18 or age=34;
select name,age from students where age=18 or age=34 or age=12;
select name,age from students where age in (12, 18, 34);
-- not in 不非連續的範圍之內
-- 年齡不是 18、34歲之間的資訊
select name,age from students where age not in (12, 18, 34);
-- between ... and ...表示在一個連續的範圍內
-- 查詢 年齡在18到34之間的的資訊
select name, age from students where age between 18 and 34;
-- not between ... and ...表示不在一個連續的範圍內
-- 查詢 年齡不在在18到34之間的的資訊
select * from students where age not between 18 and 34;
select * from students where not age between 18 and 34;
-- 失敗的select * from students where age not (between 18 and 34);
-- 空判斷
-- 判空is null
-- 查詢身高為空的資訊
select * from students where height is null;
select * from students where height is NULL;
select * from students where height is Null;
-- 判非空is not null
select * from students where height is not null;
-- 排序
-- order by 欄位
-- asc從小到大排列，即升序
-- desc從大到小排序，即降序
-- 查詢年齡在18到34歲之間的男性，按照年齡從小到到排序
select * from students where (age between 18 and 34) and gender=1;
select * from students where (age between 18 and 34) and gender=1 order by age;
select * from students where (age between 18 and 34) and gender=1 order by age asc;
-- 查詢年齡在18到34歲之間的女性，身高從高到矮排序
select * from students where (age between 18 and 34) and gender=2 order by height desc;
-- order by 多個欄位
-- 查詢年齡在18到34歲之間的女性，身高從高到矮排序, 如果身高相同的情況下按照年齡從小到大排序
;
-- 查詢年齡在18到34歲之間的女性，身高從高到矮排序, 如果身高相同的情況下按照年齡從小到大排序,
-- 如果年齡也相同那麼按照id從大到小排序
select * from students where (age between 18 and 34) and gender=2 order by height desc,age asc,id desc;
-- 按照年齡從小到大、身高從高到矮的排序
select * from students order by age asc, height desc;
-- 聚合函式
-- 總數
-- count
-- 查詢男性有多少人，女性有多少人
select * from students where gender=1;
select count(*) from students where gender=1;
select count(*) as 男性人數 from students where gender=1;
select count(*) as 女性人數 from students where gender=2;
-- 最大值
-- max
-- 查詢最大的年齡
select age from students;
select max(age) from students;
-- 查詢女性的最高 身高
select max(height) from students where gender=2;
-- 最小值
-- min
-- 求和
-- sum
-- 計算所有人的年齡總和
select sum(age) from students;
-- 平均值
-- avg
-- 計算平均年齡
select avg(age) from students;
-- 計算平均年齡 sum(age)/count(*)
select sum(age)/count(*) from students;
-- 四捨五入 round(123.23 , 1) 保留1位小數
-- 計算所有人的平均年齡，保留2位小數
select round(sum(age)/count(*), 2) from students;
select round(sum(age)/count(*), 3) from students;
-- 計算男性的平均身高 保留2位小數
select round(avg(height), 2) from students where gender=1;
-- select name, round(avg(height), 2) from students where gender=1;
-- 分組
-- group by
-- 按照性別分組,查詢所有的性別
select name from students group by gender;
--select * from students group by gender;
select gender from students group by gender;
-- 失敗select * from students group by gender;
-- 計算每種性別中的人數
select gender,count(*) from students group by gender;
-- 計算男性的人數
select gender,count(*) from students where gender=1 group by gender;
-- group_concat(...)
-- 查詢同種性別中的姓名
select gender,group_concat(name) from students where gender=1 group by gender;
select gender,group_concat(name, age, id) from students where gender=1 group by gender;
select gender,group_concat(name, "_", age, " ", id) from students where gender=1 group by gender;
-- having
-- 查詢平均年齡超過30歲的性別，以及姓名 having avg(age) > 30
select gender, group_concat(name),avg(age) from students group by gender having avg(age)>30;
-- 查詢每種性別中的人數多於2個的資訊
select gender, group_concat(name) from students group by gender having count(*)>2;
-- 分頁
-- limit start, count
-- 限制查詢出來的資料個數
select * from students where gender=1 limit 2;
-- 查詢前5個資料
select * from students limit 0, 5;
-- 查詢id6-10（包含）的書序
select * from students limit 5, 5;
-- 每頁顯示2個，第1個頁面
select * from students limit 0,2;
-- 每頁顯示2個，第2個頁面
select * from students limit 2,2;
-- 每頁顯示2個，第3個頁面
select * from students limit 4,2;
-- 每頁顯示2個，第4個頁面
select * from students limit 6,2; -- -----> limit (第N頁-1)*每個的個數, 每頁的個數;
-- 每頁顯示2個，顯示第6頁的資訊, 按照年齡從小到大排序
-- 失敗select * from students limit 2*(6-1),2;
-- 失敗select * from students limit 10,2 order by age asc;
select * from students order by age asc limit 10,2;
select * from students where gender=2 order by height desc limit 0,2;
-- 連線查詢
-- inner join ... on
-- select ... from 表A inner join 表B;
select * from students inner join classes;
-- 查詢 有能夠對應班級的學生以及班級資訊
select * from students inner join classes on students.cls_id=classes.id;
-- 按照要求顯示姓名、班級
select students.*, classes.name from students inner join classes on students.cls_id=classes.id;
select students.name, classes.name from students inner join classes on students.cls_id=classes.id;
-- 給資料表起名字
select s.name, c.name from students as s inner join classes as c on s.cls_id=c.id;
-- 查詢 有能夠對應班級的學生以及班級資訊，顯示學生的所有資訊，只顯示班級名稱
select s.*, c.name from students as s inner join classes as c on s.cls_id=c.id;
-- 在以上的查詢中，將班級姓名顯示在第1列
select c.name, s.* from students as s inner join classes as c on s.cls_id=c.id;
-- 查詢 有能夠對應班級的學生以及班級資訊, 按照班級進行排序
-- select c.xxx s.xxx from student as s inner join clssses as c on .... order by ....;
select c.name, s.* from students as s inner join classes as c on s.cls_id=c.id order by c.name;
-- 當時同一個班級的時候，按照學生的id進行從小到大排序
select c.name, s.* from students as s inner join classes as c on s.cls_id=c.id order by c.name,s.id;
-- left join
-- 查詢每位學生對應的班級資訊
select * from students as s left join classes as c on s.cls_id=c.id;
-- 查詢沒有對應班級資訊的學生
-- select ... from xxx as s left join xxx as c on..... where .....
-- select ... from xxx as s left join xxx as c on..... having .....
select * from students as s left join classes as c on s.cls_id=c.id having c.id is null;
select * from students as s left join classes as c on s.cls_id=c.id where c.id is null;
-- right join on
-- 將資料表名字互換位置，用left join完成
-- 自關聯
-- 省級聯動 url:http://demo.lanrenzhijia.com/2014/city0605/
-- 查詢所有省份
select * from areas where pid is null;
-- 查詢出山東省有哪些市
select * from areas as province inner join areas as city on city.pid=province.aid having province.atitle="山東省";
select province.atitle, city.atitle from areas as province inner join areas as city on city.pid=province.aid having province.atitle="山東省";
-- 查詢出青島市有哪些縣城
select province.atitle, city.atitle from areas as province inner join areas as city on city.pid=province.aid having province.atitle="青島市";
select * from areas where pid=(select aid from areas where atitle="青島市";
-- 子查詢
-- 標量子查詢
-- 查詢出高於平均身高的資訊
-- 查詢最高的男生資訊
select * from students where height = 188;
select * from students where height = (select max(height) from students);
-- 列級子查詢
-- 查詢學生的班級號能夠對應的學生資訊
-- select * from students where cls_id in (select id from classes);
-- 資料的準備
-- 建立一個資料庫
create database python_test charset=utf8;
-- 使用一個資料庫
use python_test;
-- 顯示使用的當前資料是哪個?
select database();
-- 建立一個資料表
-- students表
create table students(
id int unsigned primary key auto_increment not null,
name varchar(20), --default '',
age tinyint unsigned default 0,
height decimal(5,2),
gender enum('男','女','中性','保密'),-- default '保密',
cls_id int unsigned default 0,
is_delete bit default 0
);
-- classes表
create table classes (
id int unsigned auto_increment primary key not null,
name varchar(30) not null
);
-- 查詢
-- 查詢所有欄位
-- select * from 表名;
select * from students;
select * from classes;
select id, name from classes;
-- 查詢指定欄位
-- select 列1,列2,... from 表名;
select name, age from students;
-- 使用 as 給欄位起別名
-- select 欄位 as 名字.... from 表名;
select name as 姓名, age as 年齡 from students;
-- select 表名.欄位 .... from 表名;
select students.name, students.age from students;
-- 可以通過 as 給表起別名
-- select 別名.欄位 .... from 表名 as 別名;
select students.name, students.age from students;
select s.name, s.age from students as s;
-- 失敗的select students.name, students.age from students as s;
-- 消除重複行
-- distinct 欄位
select distinct gender from students;
-- 條件查詢
-- 比較運算子
-- select .... from 表名 where .....
-- >
-- 查詢大於18歲的資訊
select * from students where age>18;
select id,name,gender from students where age>18;
-- <
-- 查詢小於18歲的資訊
select * from students where age<18;
-- >=
-- <=
-- 查詢小於或者等於18歲的資訊
-- =
-- 查詢年齡為18歲的所有學生的名字
select * from students where age=18;
-- != 或者 <>
-- 邏輯運算子
-- and
-- 18到28之間的所以學生資訊
select * from students where age>18 and age<28;
-- 失敗select * from students where age>18 and <28;
-- 18歲以上的女性
select * from students where age>18 and gender="女";
select * from students where age>18 and gender=2;
-- or
-- 18以上或者身高查過180(包含)以上
select * from students where age>18 or height>=180;
-- not
-- 不在 18歲以上的女性 這個範圍內的資訊
-- select * from students where not age>18 and gender=2;
select * from students where not (age>18 and gender=2);
-- 年齡不是小於或者等於18 並且是女性
select * from students where (not age<=18) and gender=2;
-- 模糊查詢
-- like
-- % 替換1個或者多個
-- _ 替換1個
-- 查詢姓名中 以 "小" 開始的名字
select name from students where name="小";
select name from students where name like "小%";
-- 查詢姓名中 有 "小" 所有的名字
select name from students where name like "%小%";
-- 查詢有2個字的名字
select name from students where name like "__";
-- 查詢有3個字的名字
select name from students where name like "__";
-- 查詢至少有2個字的名字
select name from students where name like "__%";
-- rlike 正則
-- 查詢以 周開始的姓名
select name from students where name rlike "^周.*";
-- 查詢以 周開始、倫結尾的姓名
select name from students where name rlike "^周.*倫$";
-- 範圍查詢
-- in (1, 3, 8)表示在一個非連續的範圍內
-- 查詢 年齡為18、34的姓名
select name,age from students where age=18 or age=34;
select name,age from students where age=18 or age=34 or age=12;
select name,age from students where age in (12, 18, 34);
-- not in 不非連續的範圍之內
-- 年齡不是 18、34歲之間的資訊
select name,age from students where age not in (12, 18, 34);
-- between ... and ...表示在一個連續的範圍內
-- 查詢 年齡在18到34之間的的資訊
select name, age from students where age between 18 and 34;
-- not between ... and ...表示不在一個連續的範圍內
-- 查詢 年齡不在在18到34之間的的資訊
select * from students where age not between 18 and 34;
select * from students where not age between 18 and 34;
-- 失敗的select * from students where age not (between 18 and 34);
-- 空判斷
-- 判空is null
-- 查詢身高為空的資訊
select * from students where height is null;
select * from students where height is NULL;
select * from students where height is Null;
-- 判非空is not null
select * from students where height is not null;
-- 排序
-- order by 欄位
-- asc從小到大排列，即升序
-- desc從大到小排序，即降序
-- 查詢年齡在18到34歲之間的男性，按照年齡從小到到排序
select * from students where (age between 18 and 34) and gender=1;
select * from students where (age between 18 and 34) and gender=1 order by age;
select * from students where (age between 18 and 34) and gender=1 order by age asc;
-- 查詢年齡在18到34歲之間的女性，身高從高到矮排序
select * from students where (age between 18 and 34) and gender=2 order by height desc;
-- order by 多個欄位
-- 查詢年齡在18到34歲之間的女性，身高從高到矮排序, 如果身高相同的情況下按照年齡從小到大排序
;
-- 查詢年齡在18到34歲之間的女性，身高從高到矮排序, 如果身高相同的情況下按照年齡從小到大排序,
-- 如果年齡也相同那麼按照id從大到小排序
select * from students where (age between 18 and 34) and gender=2 order by height desc,age asc,id desc;
-- 按照年齡從小到大、身高從高到矮的排序
select * from students order by age asc, height desc;
-- 聚合函式
-- 總數
-- count
-- 查詢男性有多少人，女性有多少人
select * from students where gender=1;
select count(*) from students where gender=1;
select count(*) as 男性人數 from students where gender=1;
select count(*) as 女性人數 from students where gender=2;