How do you create a derived table?

Posted on by Muna Meyer

How do you create a derived table?

A derived table is a table expression that appears in the FROM clause of a query. You can apply derived tables when the use of column aliases is not possible because another clause is processed by the SQL translator before the alias name is known.

What is a derived table in Teradata?

Derived tables are an optional feature that you can specify in the FROM clause of SELECT, ABORT, ROLLBACK, and DELETE statements. You can use derived tables for these purposes: To avoid CREATE and DROP TABLE statements for storing retrieved information that is only needed for one request.

What is a derived table?

A derived table is an expression that generates a table within the scope of a query FROM clause. For example, a subquery in a SELECT statement FROM clause is a derived table: SELECT … The [AS] tbl_name clause is mandatory because every table in a FROM clause must have a name.

What is GTT in Teradata?

The definition for a global temporary table is persistent and stored in the Data Dictionary. Space usage is charged to login user temporary space. Each user session can materialize as many as 2000 global temporary tables at a time.

How do I create a multiset volatile table in Teradata?

Create Volatile Table in Teradata

  1. CREATE MULTISET VOLATILE TABLE performance_test_tmp (
  2. col1 integer NOT NULL ,
  3. col2 integer NOT NULL ,
  4. col3 integer NOT NULL)
  5. ON COMMIT PRESERVE ROWS;
  6. INSERT INTO performance_test_tmp (col1, col2, col3) VALUES (1,2,3);
  7. SELECT * FROM performance_test_tmp;

How do you create a derived table in alias?

The short answer is you need to give your subqueries an alias in your SELECT statement. Add an alias after the closing bracket of the FROM clause subquery. In other SQL vendors, this is not required, but MySQL requires you to alias your subqueries.

What is the difference between a derived table and a subquery?

A subquery is a SELECT statement that is nested within another statement….Differences Among CTE, Derived Table, Temp Table, Sub Query And Temp Variable.

Subquery Derived
Subquery can have only one column. Derived table can have one or more column.
Subquery mainly use in where clause. Derived table used in from clause.

How do I create a stored procedure in Teradata?

Teradata stored procedure is created from the following commands: BTEQ utility using the COMPILE command….Following is the syntax of the CREATE PROCEDURE statement.

  1. CREATE PROCEDURE ( [parameter 1 data type, parameter 2 data type..] )
  2. BEGIN.
  3. ;
  4. END;

What is the difference between a set table and a multiset table in Teradata?

Teradata classifies the tables as SET or MULTISET tables based on how the duplicate records are handled. A table defined as SET table doesn’t store the duplicate records, whereas the MULTISET table can store duplicate records.

How do I create a volatile table in Teradata stored procedure?

I create a stored procedure as follows: replace PROCEDURE mydb. sp_Insert_Values ( IN lastExecDate timestamp ) SQL SECURITY CREATOR BEGIN CREATE MULTISET VOLATILE TABLE vt_ref_table_1 ( Ref_Id integer, Ref_Unit_Type varchar(50) ) ON COMMIT PRESERVE ROWS; insert into mydb.