Page History

...

• A SELECT statement can be part of a union query or a subquery of another query.
• table_reference indicates the input to the query. It can be a regular table, a view, a join construct or a subquery.
• Table names and column names are case insensitive.
  • In Hive 0.12 and earlier, only alphanumeric and underscore characters are allowed in table and column names.
  • In Hive 0.13 and later, column names can contain any Unicode character (see HIVE-6013). Any column name that is specified within backticks (`) is treated literally. Within a backtick string, use double backticks (``) to represent a backtick character.
  • To revert to pre-0.13.0 behavior and restrict column names to alphanumeric and underscore characters, set the configuration property hive.support.quoted.identifiers to none. In this configuration, backticked names are interpreted as regular expressions. For details, see Supporting Quoted Identifiers in Column Names (attached to HIVE-6013). Also see REGEX Column Specification below.

• Simple query. For example, the following query retrieves all columns and all rows from table t1.

  Code Block
  language sql
  SELECT * FROM t1

• To specify a database, either qualify the table names with database names ("db_name.table_name" starting in Hive 0.7) or issue the USE statement before the query statement (starting in Hive 0.6).

  "db_name.table_name" allows a query to access tables in different databases.

  USE sets the database for all subsequent HiveQL statements. Reissue it with the keyword "default" to reset to the default database.

  Code Block
  language sql
  USE database_name; SELECT query_specifications; USE default;

...