Shulou(Shulou.com)05/31 Report--

This article mainly introduces "what are the basic operations of MySQL database and data table". In the daily operation, I believe that many people have doubts about the basic operation of MySQL database and data table. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the questions of "what are the basic operations of MySQL database and data table". Next, please follow the editor to study!

Preface

Naicat for Mysql usage

Usually, we connect to the mysql service through mysql.exe (client).

But there's a problem.

The first problem is that it is too ugly.

The second problem is because it doesn't prompt automatically. I've been accustomed to all kinds of automatic prompt tools. I'm using such Low.

Installation

The next step is the next step!

Crack

Administrator runs PatchNavicat

After opening it, navigate to the directory where Navicat for MySQL is installed and finish it.

New query

After connecting, click query, and then click New query, you can write SQL.

Some Conceptual understanding of Mysql

One concept that needs to be clarified first is that Mysql is not a database.

We are connecting to a Mysql service, not a database

So when someone hears about connecting to a database, it actually refers to the Mysql service that the connection runs.

Understanding of database

A database can be understood as a folder.

Use the show DATABASES; command to see which databases you have under you.

And then switch to

You can also find these folders.

If you data again, create a new folder.

Then through the show DATABASES; command to see which databases are currently available, you can find that there are indeed more folders (databases) that have just been created.

So we come to the conclusion that the database is actually a folder.

Understanding of data tables

The database is equivalent to a folder, and what is put in the database is the data table.

Table content

In fact, you will find that the datasheet is very similar to Excel.

Then Excel has whatever data sheet it has.

It is usually the table header (blue box) and the table content (red box).

Summary

A database is a folder.

Data tables cannot exist alone and need to be placed in the database. Xlsx is used as an example.

The database is divided into headers, table contents, rows and columns.

Database related commands

View the database under the current Mysql

Command

Show DATABASES

Result

Using the database

Using a database means.

The database is actually a folder, to use the database is to enter the database, which is equivalent to entering this folder.

Command

Use; # for example, use enters the database mysql

In daily use, if you want to operate the tables in which database, you must use this database.

Create a database

Command

CREATE DATABASE DEFAULT CHARSET utf8 COLLATE utf8_general_ci;# example to create a school database CREATE DATABASE school DEFAULT CHARSET utf8 COLLATE utf8_general_ci

Execution result

Delete database

DROP # example, delete school database DROP school

Datasheet related commands

Remember that you must use the database before you can manipulate the table.

Create a tabl

Format

Create table table name (column name column type [other parameters 1 other parameters 2.], column name column types [other parameters 1 other parameters 2...]) ENGINE=InnoDB DEFAULT CHARSET=utf8

Other parameters include

Whether it can be empty

Not null-- not nullable null-- nullable

Default value

Defalut 2-default 2

Self-increasing

Self-increment is generally used on id, and there can be only one self-increment column. You don't need to care about this column when you insert it, and you will automatically add values.

Auto_increment-- self-increment-- although it is fine to add this keyword since the primary key cannot be empty, it is necessary to cooperate with other keywords not null auto_increment primary key

Primary key

The primary key, a special unique index, does not allow null values.

If the primary key uses a single column, its value must be unique.

If it is multiple columns, the combination must be unique.

... Primary key (nid,num)

Foreign key

Constraint fk_cc foreign key (color_id) references color (nid)

Other parameters correspond to one by one.

Example

Create a master table

Create table teacher (id int not null auto_increment PRIMARY key, teacher_name varchar (16) not null) ENGINE=InnoDB DEFAULT CHARSET=utf8

Check which tables are in the database

Command

Show TABLES

Result

Delete tabl

Drop table

Clear the table

At this point in delete from truncate table, the study on "what are the basic operations of MySQL databases and data tables" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.