SQL daily practice (Niuke new question bank) - day 4: advanced operators

1. Advanced operator exercises (2）

subject ： Now I want to find a school for Peking University or GPA stay 3.7 above ( barring 3.7) Conduct research on users , Please take out the relevant data （ Use OR Realization ）

Create table statement ：

drop table if exists user_profile;
CREATE TABLE `user_profile` (
`id` int NOT NULL,
`device_id` int NOT NULL,
`gender` varchar(14) NOT NULL,
`age` int ,
`university` varchar(32) NOT NULL,
`province` varchar(32)  NOT NULL,
`gpa` float);
INSERT INTO user_profile VALUES(1,2138,'male',21,' Peking University, ','BeiJing',3.4);
INSERT INTO user_profile VALUES(2,3214,'male',null,' Fudan University ','Shanghai',4.0);
INSERT INTO user_profile VALUES(3,6543,'female',20,' Peking University, ','BeiJing',3.2);
INSERT INTO user_profile VALUES(4,2315,'female',23,' Zhejiang University ','ZheJiang',3.6);
INSERT INTO user_profile VALUES(5,5432,'male',25,' Shandong University ','Shandong',3.8);

The answer is ：

SELECT
    device_id,
    gender,
    age,
    university,
    gpa 
FROM
    user_profile 
WHERE
    gpa > '3.7'
OR 
    university = ' Peking University, '

2. Where in and Not in

subject ： Now I want to find a school for Peking University 、 Students from Fudan University and Shanda University conducted research , Please take out the relevant data .

Create table statement ：

drop table if exists user_profile;
CREATE TABLE `user_profile` (
`id` int NOT NULL,
`device_id` int NOT NULL,
`gender` varchar(14) NOT NULL,
`age` int ,
`university` varchar(32) NOT NULL,
`province` varchar(32)  NOT NULL,
`gpa` float);
INSERT INTO user_profile VALUES(1,2138,'male',21,' Peking University, ','BeiJing',3.4);
INSERT INTO user_profile VALUES(2,3214,'male',null,' Fudan University ','Shanghai',4.0);
INSERT INTO user_profile VALUES(3,6543,'female',20,' Peking University, ','BeiJing',3.2);
INSERT INTO user_profile VALUES(4,2315,'female',23,' Zhejiang University ','ZheJiang',3.6);
INSERT INTO user_profile VALUES(5,5432,'male',25,' Shandong University ','Shandong',3.8);

The answer is ：

select device_id,gender,age,university,gpa
from user_profile
WHERE university=" Peking University, " or university=" Fudan University " or university=" Shandong University "

3. Operators mix

subject ： Now I want to find gpa stay 3.5 above ( barring 3.5) Shandong University Users or gpa stay 3.8 above ( barring 3.8) Students from Fudan University conducted User Research , Please take out the corresponding data

Create table statement ：

drop table if exists user_profile;
CREATE TABLE `user_profile` (
`id` int NOT NULL,
`device_id` int NOT NULL,
`gender` varchar(14) NOT NULL,
`age` int ,
`university` varchar(32) NOT NULL,
`province` varchar(32)  NOT NULL,
`gpa` float);
INSERT INTO user_profile VALUES(1,2138,'male',21,' Peking University, ','BeiJing',3.4);
INSERT INTO user_profile VALUES(2,3214,'male',null,' Fudan University ','Shanghai',4.0);
INSERT INTO user_profile VALUES(3,6543,'female',20,' Peking University, ','BeiJing',3.2);
INSERT INTO user_profile VALUES(4,2315,'female',23,' Zhejiang University ','ZheJiang',3.6);
INSERT INTO user_profile VALUES(5,5432,'male',25,' Shandong University ','Shandong',3.8);

The answer is ：

 SELECT device_id, gender, age, university,gpa from user_profile where gpa > 3.8 and university = ' Fudan University ' UNION
SELECT device_id, gender, age, university,gpa from user_profile where gpa > 3.5 and university = ' Shandong University ' 

4. View users with Beijing in the school name

subject ： Now the operator wants to view the information of users with Beijing in all universities , Please take out the corresponding data .

Create table statement ：

drop table if exists user_profile;
CREATE TABLE `user_profile` (
`id` int NOT NULL,
`device_id` int NOT NULL,
`gender` varchar(14) NOT NULL,
`age` int ,
`university` varchar(32) NOT NULL,
`gpa` float);
INSERT INTO user_profile VALUES(1,2138,'male',21,' Peking University, ',3.4);
INSERT INTO user_profile VALUES(2,3214,'male',null,' Fudan University ',4.0);
INSERT INTO user_profile VALUES(3,6543,'female',20,' Peking University, ',3.2);
INSERT INTO user_profile VALUES(4,2315,'female',23,' Zhejiang University ',3.6);
INSERT INTO user_profile VALUES(5,5432,'male',25,' Shandong University ',3.8);
INSERT INTO user_profile VALUES(6,2131,'male',28,' Beijing Normal University ',3.3);

The answer is ：

select device_id,age,university
from user_profile
-- where university like '% Beijing %';
WHERE university regexp " Beijing ";
--  Regular expressions are used to match special strings of text （ Character set ）（ Matching text , Put a pattern （ Regular expressions ） Compare with a text string ）.

-- LIKE  and  REGEXP Important differences between 
-- LIKE  Match the entire column , If the matched text appears in the column value ,LIKE  It will not be found , The corresponding row is not returned （ Unless you use wildcards ）. and  REGEXP  Match within column values , If the matched text appears in the column value ,REGEXP  It will be found , The corresponding line is returned , also  REGEXP  Can match the entire column value （ And  LIKE  Same effect ）.

5. How to make question brushing more efficient ?

Recently, many kids who have learned the basics asked me how to improve my programming level ？ What should I do after learning the basics ？ Mingming learned a lot , Do the project but don't know how to get started , In fact, this is too little practice , Only pay attention to learning , But ignore the question , Only continuous practice can improve and consolidate programming thinking and ability ！

Link address ： Cattle from | SQL Brush topic , Stop talking nonsense and speed up ！！！