【CS 61a study notes 9】HIVE SQL

P.S. : all the sql codes in this note are based on hive sql , so may be a little different with 61a sql part, mysql,oracle,etc.
most of the content in this note is based on my work experiences.JUST A RECORD

Executing order of SQL

Bacis syntax

CREATE

• CREATE (TEMP or TEMPORARY) TABLE table_name (data) ;
• CREATE (TEMP or TEMPORARY) TABLE table_name AS SELECT … ;

INSERT

• INSERT INTO table_name VALUES() ;
• INSERT OVERWRITE table_name VALUES() ;
  • For partitioned tables, the insert overwrite table operation overwrites the data in the specified partition without affecting the data in other partitions.
  • **INSERT OVERWRITE TABLE table_name PARTITION(target_partition) SELECT … **
  • For a normal table (that is, a non-partitioned table), the insert overwrite table operation completely overwrites