Database (Linux)

Hierarchical database

Tree-shaped. 1:n

Mesh Database

The mesh. Can be converted into hierarchical database by mathematical method

relational database

Convert relational database relationships into simple two-time patterns

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Create or select a database

Sqlite3 study.db

View Database

. databases

Exit database

. Quit

Create a table

CREATE TABLE Department (

Int

CHAR

TEXT

REAL

)

View Table

. Table

View table Structure

. Schema Comany

Check all table Structures

. Schema

Delete a table

drop TABLE Department;

Insert content into a table

1. INSERT into company values (.......) The values (...) are not the same as those of the ". ...."
2. INSERT into company values (.............);.);

Format Control

. Head On

. Mode column

Find table Contents

Select *from Company

WHERE clause

1. SELECT * FROM company where id= 7;
2. Operators:> < >= <= and or not like Glob exists
3. SELECT * FROM company where age= in (25,27);
4. The age of 25 or 27 years
5. SELECT * from Companny where age between and 27;
6. Age 22--27
7. SELECT * FROM company where age is not null;
8. Age cannot be empty
9. SELECT * FROM company where exists (select Age company wherer salary >65000);

Like child statement and Glob child statement

1. SELECT * from company where name like ' p% '; case insensitive
2. SELECT * FROM company where Glob ' p* ';

Limit statement

Limit the amount of return that matches a condition

1. SELECT * FROM company where age <30 limit 2;
2. SELECT * from company limit 2;
3. Select *from compay limit 2 offset 2;

ORDER BY clause

ASC Ascending DeSc Descending

Database (Linux)