SQL 创建数据库

In this tutorial you will learn how to create database in a relational database management system like, MySQL, SQL Server, etc. using SQL.

## Creating a Database
Before doing anything with the data we must need to create a database first. We're assuming that you already have a MySQL, or SQL Server available for your use, as well as you've all the necessary privileges, if not please check out the [getting started guide](http://www.bixiaguangnian.com/manual/sql/3387.html "getting started guide").

The SQL `CREATE DATABASE` statement is used to create a database.

## Syntax
The basic syntax for creating a database can be given with:

```sql
CREATE DATABASE database_name;
```
The following SQL statement creates a database named demo:

```sql
CREATE DATABASE demo;
```
Creating a database does not select it for use. So, before moving further we must need to select the target database with the `USE` statement. For example, the `USE demo`; command sets the demo database as target database for all future commands.

<div class="callout callout-info mb-3">Note: In Unix, the database and table names are case-sensitive, so you must always refer to your database as demo, not as Demo, DEMO, or something else. But, SQL keywords are case-insensitive, like CREATE DATABASE is same as create database.</div>

## Creating Database in MySQL
Let's create a database in MySQL using the command-line tool.

### Step 1: Invoke the MySQL command-line tool
To invoke the MySQL command line, we've to log in to the MySQL server first. To log in as `root` user, type the following command in terminal and press enter. You will be asked for your password. Enter your password and press enter, if it is correct the `mysql>` prompt will appear, via which you will be able to issue SQL statements and view the results.

```shell
shell> mysql -u root -p
```
### Step 2: Creating a MySQL Database
Now, execute the following command to create the database named demo.

```shell
mysql> CREATE DATABASE demo;
```
If the database created successfully you'll see the output something like this:

```
Query OK, 1 row affected (0.03 sec)
```
If you try to create a database that is already exists you'll get an error message. To avoid this in MySQL you can use an optional clause `IF NOT EXISTS` as follow:

```shell
mysql> CREATE DATABASE IF NOT EXISTS demo;
```
### Step 3: Selecting the Database
Type the following command and press enter. You will see the output "Database changed". Now our demo database is selected as default database for all future operations.

```shell
mysql> USE demo;
```
<div class="callout callout-success mb-3">Tip: If you want to see a list of existing databases on the MySQL server, you can execute the statement SHOW DATABASES; on the command line.</div>