Cum se creează o bază de date în MySQL (Crea MySQL Mese)

Pași pentru a crea o bază de date în MySQL

A database in MySQL is a named container for tables, views, and related objects. You can create one in two ways:

1) Prin executarea unei interogări SQL simplă

2) Prin utilizarea ingineriei avansate în MySQL Banc de lucru

As SQL începător, să ne uităm mai întâi la metoda de interogare.

Cum se creează o bază de date în MySQL

Iată cum se creează o bază de date în MySQL:

CREATE DATABASE este comanda SQL folosită pentru crearea unei baze de date în MySQL.

Imagine you need to create a database with the name “movies”. You can create a database in MySQL by executing the following SQL command.

CREATE DATABASE movies;

Note: You can also use the command CREATE SCHEMA instead of CREATE DATABASE.

The statement works only once. Running it again throws an error, so let’s improve the query with more parameters.

DACĂ NU EXISTĂ

Un singur MySQL server can hold many databases. When several people share that server, you may try to create a database with the name of an existing one.

DACĂ NU EXISTĂ îl instruiește pe MySQL server to check for a database with the same name before creating it. The database is created only if the name is free; without this clause, MySQL aruncă o eroare.

CREATE DATABASE IF NOT EXISTS movies;

Once the database name is safe, the next decision is how MySQL should store and compare the text inside it.

Colaţionare şi set de caractere

A set de caractere decides which characters a column can store, while a gustare este setul de rules used in comparison and sorting. Both can be defined at four levels: server, database, table, and column.

The collation you choose depends on the character set. For instance, the latin1 character set uses the latin1_swedish_ci collation, which is the Swedish case-insensitive order.

CREATE DATABASE IF NOT EXISTS movies CHARACTER SET latin1 COLLATE latin1_swedish_ci;

For local languages such as Arabic or Chinese, select the Unicode utf8mb4 character set, which stores every Unicode character, including emoji. In MySQL 8.0, utf8mb4 is the default character set and utf8mb4_0900_ai_ci the default collation.

CREATE DATABASE IF NOT EXISTS movies CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci;

Puteți găsi lista cu toate colațiile și seturile de caractere aici.

You can see the list of existing databases by running the following SQL command.

SHOW DATABASES;

With the database in place, you can now add the tables that will actually hold the records.

Cum se creează un tabel în MySQL

The CREATE TABLE command is used to create tables in a database.

As the diagram shows, every table belongs to one database. Tables are created with the CREAȚI TABEL statement, which has the following syntax.

CREATE TABLE [IF NOT EXISTS] `TableName` (`fieldname` dataType [optional parameters]) ENGINE = storage Engine;

AICI

• “CREATE TABLE” is responsible for the creation of the table in the database.
• “[IF NOT EXISTS]” is optional and only creates the table if no matching table name is found.
• “`fieldName`” is the name of the field, and “data Type” defines the nature of the data stored in it.
• “[optional parameters]” is extra information about a field, such as “AUTO_INCREMENT” or NOT NULL.
• “storage Engine” manages the table, normally InnoDB, which supports transactions and foreign keys.

MySQL Creați un exemplu de tabel

Mai jos este a MySQL example to create a table in a database:

CREATE TABLE IF NOT EXISTS `MyFlixDB`.`Members` (
  `membership_number` INT AUTO_INCREMENT ,
  `full_names` VARCHAR(150) NOT NULL ,
  `gender` VARCHAR(6) ,
  `date_of_birth` DATE ,
  `physical_address` VARCHAR(255) ,
  `postal_address` VARCHAR(255) ,
  `contact_number` VARCHAR(75) ,
  `email` VARCHAR(255) ,
  PRIMARY KEY (`membership_number`) )
ENGINE = InnoDB;

Notă: corectă MySQL cuvântul cheie este AUTO_INCREMENT with an underscore. AUTOINCREMENT aparține lui SQLite and raises a syntax error in MySQL.

Every column carries a data type, so choose carefully: neither underestimate nor overestimate the range of data you expect.

MySQL Tipuri de date

Data types define the nature of the data that can be stored in a particular column of a table.

MySQL are 3 main categories of data types, namely:

1. Numeric
2. Text
3. Data / ora

Tipuri de date numerice

Numeric data types are used to store numeric values. It is very important to make sure the range of your data is between the lower and upper boundaries of the numeric data type you pick.

Tipuri de date text

As the data type category name implies, these are used to store text values. Always make sure the length of your textual data does not exceed the maximum length of the column.

Tipuri de date pentru dată și oră

Date and time data types store calendar and clock values in a fixed format, which keeps sorting and comparison reliable.

Other Data Types

Apart from the above, there are some other data types in MySQL.

Now let’s see a query for creating a table which uses all the data types. Study it and identify how each data type is defined in the below create table MySQL exemplu.

CREATE TABLE `all_data_types` (
    `varchar` VARCHAR( 20 )  ,
    `tinyint` TINYINT  ,
    `text` TEXT  ,
    `date` DATE  ,
    `smallint` SMALLINT  ,
    `mediumint` MEDIUMINT  ,
    `int` INT  ,
    `bigint` BIGINT  ,
    `float` FLOAT( 10, 2 )  ,
    `double` DOUBLE  ,
    `decimal` DECIMAL( 10, 2 )  ,
    `datetime` DATETIME  ,
    `timestamp` TIMESTAMP  ,
    `time` TIME  ,
    `year` YEAR  ,
    `char` CHAR( 10 )  ,
    `tinyblob` TINYBLOB  ,
    `tinytext` TINYTEXT  ,
    `blob` BLOB  ,
    `mediumblob` MEDIUMBLOB  ,
    `mediumtext` MEDIUMTEXT  ,
    `longblob` LONGBLOB  ,
    `longtext` LONGTEXT  ,
    `enum` ENUM( '1', '2', '3' )  ,
    `set` SET( '1', '2', '3' )  ,
    `bool` BOOL  ,
    `binary` BINARY( 20 )  ,
    `varbinary` VARBINARY( 20 )
) ENGINE = MYISAM;

Cele mai bune practici pentru crearea a MySQL Baza de date

A few conventions keep your scripts readable:

• Use upper case letters for SQL keywords, i.e. “DROP SCHEMA IF EXISTS `MyFlixDB`;”
• End all your SQL commands using semicolons.
• Avoid using spaces in schema, table, and field names. Use underscores instead to separate schema, table, or field names.
• Prefer InnoDB over MyISAM for new tables, because InnoDB supports transactions, row-level locking, and foreign keys.

The query method is complete. The second route reaches the same database from a visual model instead of hand-written SQL.

Cum se creează MySQL Workbench ER Diagram Forward Engineering

MySQL Banc de lucru are utilități care suportă inginerie avansată. Inginerie avansată is the technical term that describes the process of translating a logical model into a physical implementation automatically.

Am creat un Diagrama ER în a noastră Modelare ER lesson. We will now use that ER model to generate the SQL scripts that will create our database.

Crearea bazei de date MyFlix din modelul MyFlix ER

Step 1) Open the ER model of the MyFlix database pe care l-ai creat mai devreme.

Pasul 2) Selectați inginerul de avans

Click on the Database menu and select Forward Engineer.

Step 3) Connection options

The next window allows you to connect to an instance of MySQL server. Click on the stored connection drop-down list and select local host. Click Execute.

Step 4) Select the options shown below

Select the options shown below in the wizard that appears. Click Next.

Step 5) Keep the selections default and click Next

The next screen shows the summary of objects in our EER diagram. Our MyFlix DB has 5 tables. Keep the selections default and click Next.

Pas 6) Revvezi scriptul SQL

The window below previews the SQL script that creates our database. Save the script to a *.sql file or copy it to the clipboard, then click Next.

Step 7) Commit progress

The window below appears once the database is created on the selected MySQL server instance. The tables from the ER model now exist physically on the server.

The database along with dummy data is attached. We will use this DB in the lessons that follow. Simply import it in MySQL Workbench to get started.

Faceți clic aici pentru a descărca MyFlixDB

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