默認數據庫"default"

可以顯式切換數據庫：hive> use 數據庫名;

創建

hive>CREATE DATABASE ?
[IF NOT EXISTS] mydb ?
[LOCATION] '/.......' ?
[COMMENT] '....';

實例

hive (default)> create database test_db comment 'test database';
OK
Time taken: 0.33 seconds

hive (default)> create database if not exists test_db comment 'test database';
OK
Time taken: 0.013 seconds

hive (default)> create database if not exists test2_dblocation'/home/hive2.1/test_database';
OK
Time taken: 0.054 seconds

注意：location 不是linux的文件系統，是hdfs的。location是指定目錄，

如果不指定會默認放到/user/hive/warehouse 下。下面查看可知。

hive (test2_db)> describe database test2_db;
OK
db_name comment location ? ? ? ?owner_name ? ? ?owner_type ? ? ?parameters
test2_db ? ? ? ? ? ? ? ?hdfs://hello110:9000/home/hive2.1/test_database hadoop ?USER

Linux文件系統里沒有
[hadoop@hello110 test_database]$ pwd
/home/hive2.1/test_database
[hadoop@hello110 test_database]$ ll
total 0

顯示

hive>SHOW DATABASES;

描述

hive>DESCRIBE DATABASE [extended] mydb;

刪除

hive>DROP DATABASE [IF EXISTS] mydb [CASCADE];

實例

hive (test2_db)> drop database test2_db;
FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask. InvalidOperationException(message:Database test2_db is not empty. One or more tables exist.)

cascade關鍵字，強制刪除，hive會把文件移動hdfs回收站

hive (test2_db)> drop database test2_db cascade;
Moved: 'hdfs://hello110:9000/home/hive2.1/test_database/t1' to trash at: hdfs://hello110:9000/user/hadoop/.Trash/Current
Moved: 'hdfs://hello110:9000/home/hive2.1/test_database' to trash at: hdfs://hello110:9000/user/hadoop/.Trash/Current
OK
Time taken: 1.384 seconds
hive (test2_db)>?