Hive 简明教程

Hive - Create Database

Hive 是一种数据库技术，用于定义可分析结构化数据的数据库和数据表。结构化数据分析的主题是将数据以表格形式进行存储，并传递查询以进行分析。本章解释了如何创建 Hive 数据库。Hive 包含一个名为 default 的默认数据库。

Hive is a database technology that can define databases and tables to analyze structured data. The theme for structured data analysis is to store the data in a tabular manner, and pass queries to analyze it. This chapter explains how to create Hive database. Hive contains a default database named default.

Create Database Statement

Create Database 是一款用于在 Hive 中创建数据库的语句。Hive 中的数据库是 namespace 或一系列数据表。此语句的 syntax 如下：

Create Database is a statement used to create a database in Hive. A database in Hive is a namespace or a collection of tables. The syntax for this statement is as follows:

CREATE DATABASE|SCHEMA [IF NOT EXISTS] <database name>

此处，IF NOT EXISTS 是一个可选项，用于通知用户是否已存在同名数据库。我们可以在此命令中使用 SCHEMA 代替 DATABASE。执行以下查询可创建名为 userdb 的数据库：

Here, IF NOT EXISTS is an optional clause, which notifies the user that a database with the same name already exists. We can use SCHEMA in place of DATABASE in this command. The following query is executed to create a database named userdb:

hive> CREATE DATABASE [IF NOT EXISTS] userdb;

or

or

hive> CREATE SCHEMA userdb;

使用以下查询可验证数据库列表：

The following query is used to verify a databases list:

hive> SHOW DATABASES;
default
userdb

JDBC Program

以下为创建数据库的 JDBC 程序。

The JDBC program to create a database is given below.

import java.sql.SQLException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.sql.DriverManager;

public class HiveCreateDb {
   private static String driverName = "org.apache.hadoop.hive.jdbc.HiveDriver";

   public static void main(String[] args) throws SQLException {
      // Register driver and create driver instance

      Class.forName(driverName);
      // get connection

      Connection con = DriverManager.getConnection("jdbc:hive://localhost:10000/default", "", "");
      Statement stmt = con.createStatement();

      stmt.executeQuery("CREATE DATABASE userdb");
      System.out.println(“Database userdb created successfully.”);

      con.close();
   }
}

将程序保存到名为 HiveCreateDb.java 的文件中。使用以下命令编译并执行此程序。

Save the program in a file named HiveCreateDb.java. The following commands are used to compile and execute this program.

$ javac HiveCreateDb.java
$ java HiveCreateDb

Output:

Database userdb created successfully.