Detailed explanation of mysql database (ubuntu 14.0.4 LTS 64)

Today I will review the concept of mysql for you and give a detailed analysis of mysql based on ubuntu 14.0.4 LTS 64-bit. Friends in need can refer to it.

1.The composition and related concepts of mysql database

First understand that mysql is a relational database, and a non-relational database The biggest difference is that the concept of table is different.

+The entire mysql environment can be understood as the largest database: A

+Database B created with mysql belongs to A and is a data warehouse, equivalent to a folder in the system

+Data table C: It is a specific place to store data, which is equivalent to a file in the system. A database B contains several data tables C (note that database B and A here are different)

+Record D: A row in the data table is called a record. Therefore, when we create the data table, we must create an id column to identify "which record is this". The values ​​of the id column cannot be the same. It must be unique, just like an ID number. There can be multiple records in a table C D

+Field E: Each column in a table is called a "field". Each field in the database has regulations, such as: field Data type, empty or not empty judgment, automatic growth, etc. A record D can have multiple fields E.

+Data F: The intersection of rows and columns is the real "data" F.

2. Examples of common commands for basic database operations (ubuntu environment).

2.1 Log in to mysql: mysql-uroot-p-u: Log in with user name, -p: Enter password

2.2 View the database: After entering the above command You will be asked to enter a password. After successful login, the interface as shown above will be displayed. View the data B

showdatabases that comes with system A; pay attention to the semicolon. The database that comes with the system is shown in the figure below.

2.3 Create database: create database mytest; This creates a database B with the name of mytest.

2.4 Among the above four databases, how to choose the database we want? usemytest, this will select our database mytest.

2.5 If you want to delete the database: dropdatabasemytest will delete the database without prompting.

2.6 Check the current status: status;

##2.7 Display table C in the current database. There are two ways below. a:showtables;b:showtablesFROMmytest;.where mytest is the database we established.

2.8 Creation and deletion of data tables

createtablemytable(idint,nameint);

droptablemytable;

2.9 How to use the established data table, that is, how to

insert data into the data table? insertintomytable(id,name)values(1,10);

2.10 Query the data in the table, selectid, namefrommytablewhereid=1order; or select*frommytable

2.11 Update the data in the table, update mytable set name=20 where id=1;

2.12 Delete the table: deletefrommytable; or droptablemytable;

2.13 Modification of table structure

(1) Add a field format:

altertabletable_nameaddcolumn (field name field type); --- This method has brackets

(2) Specify the field Inserted position:

altertabletable_nameaddcolumn field name field type after a certain field;

(3) Modify field name/type

altertabletable_namechange old field name new field name new field type ;

(4) Change the name of the table

altertabletable_namerenametonew_table_name;

(5) Clear all the data in the table at one time

truncatetabletable_name;This method also Will cause the number picker (ID) in the table to start from 1

(6) Delete a field:

altertabletable_namedrop field name;

2.14 Modify password format: mysqladmin- uusername -p old password password new password;

2.15 Display the structure of the table: describemytables;

2.16 Display the current database and user show database( ); show user();

3 Note:

3.1 If you find that you forgot to add a semicolon after pressing Enter when typing the command, you do not need to repeat it. Type the command again, just hit a semicolon and press Enter.

3.2 You can use the cursor up and down keys to call up previous commands.

# I believe you have mastered the methods after reading these cases. For more exciting information, please pay attention to other related articles on the php Chinese website!

Related reading:

AJAX implementation of simple registration page asynchronous request example code

Using jQuery+Ajax in PHP Paging query function

Detailed example of ajax implementation of uploading files without refreshing

The above is the detailed content of Detailed explanation of mysql database (ubuntu 14.0.4 LTS 64). For more information, please follow other related articles on the PHP Chinese website!