15.10 - FROM Clause - Teradata Database

Teradata Database SQL Data Definition Language Syntax and Examples

Teradata Database
December 2015
Programming Reference

For more information about the FROM clause, see SQL Data Manipulation Language, B035-1146.

FROM table_name
The name of a table containing the column or columns to include in the join index or the name of a table to join with at least one other table to form a join index. You cannot define a join index on any of the following database objects:
  • Global temporary tables
  • Hash indexes
  • Join indexes
  • Journal tables
  • Ordinary views
  • Queue tables
  • Recursive views
  • Volatile tables
Each table in the FROM clause should have at least one column in either the fixed column_name list or in the repeating column_name list, if you are using row-compression.
In a single-table join index, the column_name list must contain all columns in the FROM clause table.
You can only define column partitioning for a single-table join index.
Each table name can be qualified by a database name if necessary and can have a maximum of 64 different columns referenced in the entire join index definition.
Every table must be connected to at least one other table with a join condition. The cross join and full outer join conditions are not supported.
The maximum number of table_name references allowed is the same as the system limit for SELECT requests.
A FROM clause can have any number of simple tables, but is limited to a single joined non-simple table expression. For example, you can use a simple table list or a single non-simple table expression:
FROM table_1, table_2, table_3,  table_4
FROM (table_1 INNER JOIN table_2 ON x1 = x2)
INNER JOIN (table_3 ON x1 = x3)
The following example is not allowed because it has more than one non-simple table expression:
 FROM (table_1 INNER JOIN table_2   ON table_1 x1 = x2),(table_3 
 INNER JOIN table_4 ON x3 = x4)
An optional database name if table_name is contained in a database other than the current database.
An optional user name if table_name is contained in a user other than the current or user.
AS correlation_name
An alias for table_name.
The keyword AS preceding correlation_name is optional.