Data Analysis Tools - DDL operations & DML operations in HQL

DDL operations in HQL

Create table statement

1) table creation method:

Create table:

CREATE [EXTERNAL] TABLE [IF NOT EXISTS] table_name  [(col_name data_type [COMMENT col_comment], ...)]  [COMMENT table_comment]   [PARTITIONED BY (col_name data_type [COMMENT col_comment], ...)]  [CLUSTERED BY (col_name, col_name, ...) [SORTED BY (col_name [ASC|DESC], ...)] INTO num_buckets BUCKETS]  [ROW FORMAT row_format]  [STORED AS file_format]  [LOCATION hdfs_path]

Description:

1.1) CREATE TABLE creates a table with the specified name.If a table with the same name already exists, an exception is thrown; the user can ignore this exception with the IF NOT EXISTS option.

1.2) The EXTERNAL keyword allows users to create an external table and specify a path (LOCATION) pointing to the actual data while creating the table. When Hive creates an internal table, it will move the data to the path pointed to by the data warehouse; ifCreate an external table that only records the path where the data is located, without making any changes to the location of the data.When a table is dropped, the metadata and data of the internal table will be included together