Fundamentals of SQL database operation

MySQL Basic operation

1. Connect to database

Enter the command ：

mysql -u root -p

After that Enter password Enter the database password

2. Display all database names in the system

Enter the command ： show databases;

Be careful ： most SQL Command to ; End of character .

3. New database student

Enter the command ：

create database student ;

Again using show databases; Look at the results .

 4. Using a database student

command ： 

use student;

5. In the database student Create a table result 

command ： create table result (id int(8),name varchar(20),city varchar(20),score int(5));

6. In the table result Add data to

stay result Insert data

command ：

insert into result(id,name,city,score) values(1,"wang","beijing",75);

Be careful When defining the form, you define the type for each data among id , score by int Integer type When adding data, increase the integer

name,city Defined characters char so When adding data increase "wang" "bengjing" Put in quotation marks .

Repeat adding data similar to the above command .

After successful insertion Use select * from result; see result Everything in the table . 

7. In the table result Delete in 1 Data

for example , Delete name = "han" This data of .

delete from result where name = "han"; 

After deleting successfully see select * from result;.

8. Modify table result Data in the  

for example , modify name = "zhou" The data of , Put it id Set to 4.

update result set id=4 where name ="zhou" ;

View results

 9. Query table result Data in

for example ：

select * from result ; // Query all fields in the table

select name,score,cty from result ; // In the query table name,score,city Field  .

select score from result where name ="li"; // Inquire about name by li Of the students score.

  The second part ：MYSQL Advanced operation

1.order by Usage of

（1） take result The data in the table is ranked from high to low ;

select * from result order by score desc;  // among ,desc Representation of descending order ,asc Expressing ascending order , If no parameter is added here, the default sorting is in ascending order .