头歌hive表ddl操作(二)答案

在Hive中，DDL（数据定义语言）操作主要用于创建、修改和删除数据库、表、视图等对象。以下是一些常见的Hive表DDL操作及其示例： 1. **创建表** ```sql CREATE TABLE employees ( id INT, name STRING, salary FLOAT, department STRING ) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' STORED AS TEXTFILE; ``` 2. **创建外部表** ```sql CREATE EXTERNAL TABLE external_employees ( id INT, name STRING, salary FLOAT, department STRING ) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' STORED AS TEXTFILE LOCATION '/path/to/data'; ``` 3. **修改表** ```sql ALTER TABLE employees ADD COLUMNS (age INT); ``` 4. **删除表** ```sql DROP TABLE employees; ``` 5. **重命名表** ```sql ALTER TABLE employees RENAME TO staff; ``` 6. **创建分区表** ```sql CREATE TABLE employees_partitioned ( id INT, name STRING, salary FLOAT, department STRING ) PARTITIONED BY (country STRING) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' STORED AS TEXTFILE; ``` 7. **添加分区** ```sql ALTER TABLE employees_partitioned ADD PARTITION (country='USA'); ``` 8. **删除分区** ```sql ALTER TABLE employees_partitioned DROP PARTITION (country='USA'); ``` 这些操作可以帮助你在Hive中管理和组织数据。通过DDL操作，你可以创建复杂的表结构，管理和优化数据的存储和查询。