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How to use EXTRACT function with date and time columns

Using Extract function with any date field is easy. Let’s try this out with system date and system time commands. To see the current date we use SELECT DATE; This would give output as "11/06/2007". Suppose you want to EXTRACT the month from the date then use this query SELECT EXTRACT (MONTH FROM date); This would give "11" as the output. Similarly for YEAR and DAY use the following commands SELECT EXTRACT (YEAR FROM date); SELECT EXTRACT (DAY FROM date); But for [+]

Usage of Macro in Teradata

A macro is created to execute a single or a set of SQL statements in a single execution. Each time the macro is run all of the SQL statements present inside the macro are executed and results are returned after the end of all the SQL present inside the macro. Why do we need a macro? If there is a set of frequently used SQL statement which are being repeatedly executed, this set of SQL statement [+]

Creating Column Aliases in Teradata

When you want the column name of the table to appear differently in your SQL query, just to make sure that you too can do some magic, you can use aliases. Though aliases can also be created for various database objects like tables, views, stored procedures and macros, it is the column aliases that are more frequently used. Aliases are also referred as correlation name. Except for having a better readability, column aliases can also [+]

What is a Derived Column

A derived column is a result of a calculation (most of the time mathematical) that happens during the SQL query processing and generates a new column which is not part of the original table definition. For example, in our table we have salary column present but when we want to extract a percentage of the salary or portion of the salary, we generally create a column on the fly with the mathematical calculation from the [+]

SELECT Query with Examples

In this Section we are going to try out all possible simple SELECT queries. First lets create a sample table called emp which should have rows like the following. emp_no dept_no first_name last_name salary 7000 114 Read Vitamin 62,000 4000 113 John Row 55,000 5000 114 Robert Howard 65,000 2000 112 Larry King 60,000 1000 112 Philip Josheph 65,000 6000 115 Tony Peter 72,000 3000 111 Micheal Reed 46,000 8000 113 Philip Josheph 65,000 9000 115 Tony Peter 72,000 1100 114 Micheal Reed 46,000 Follow this command to create a temporary table: CREATE SET VOLATILE TABLE emp, NO FALLBACK, CHECKSUM = DEFAULT, LOG ( "emp_no" INTEGER, "dept_no" VARCHAR (10), "first_name" CHAR (20) CHARACTER SET LATIN NOT CASESPECIFIC, "last_name" [+]

Teradata Components

The Teradata system comprises of several interconnected software and hardware which intercommunicate within each other to bring out the best of Teradata as a whole. Following are the main components in the Teradata system. Call Level Interface (CLI) Data Communications Manager or Teradata Director Program (TDP) Parser and Dispatcher or Parsing Engine (PE) Interprocessor Network (BYNET) Database Manager or Access Module Processor (AMP) File System Disk Subsystem [+]

Transaction Management

The principle objective of a transaction is to facilitate data completeness when a sequence of events happens. Although it is not necessary that a “sequence of events” has to take place. A single event can also be considered as a transaction. A single event could be any data manipulation events like INSERTING, UPDATING or DELETING a row or set of rows. Transaction is a logical unit of work. When we say a logical unit, it means [+]

Creating Tables with SET and MULTISET

When creating tables in Teradata, it is important to consider whether or not you want to allow duplicate values in the table. The SET and MULTISET clauses are used in CREATE TABLE statement in Teradata with characteristics to allow duplicate in the table or NOT. If you specify SET, which adheres to relational data model, it will NOT allow duplicate rows in a table. On the other hand, MULTISET concept follows multidimensional data model and [+]

A Brief Introduction On Teradata.

Teradata Corporation is a global leader in providing data warehousing technologies. Almost all of the largest data warehouses on earth use Teradata RDBMS. Teradata was formerly a division of NCR Corporation with their headquarters in Dayton. They spin-off from NCR on October 1, 2007 and now a truly technology oriented company. Teradata is a complete relational database management system with its massively parallel processing mechanism running on distributed computing architecture which is scalable in all dimensions [+]

Using “GROUP BY” instead of “DISTINCT” clause

If there is a need to SELECT unique rows from a table present in Teradata, a better performance oriented query option would be to use the GROUP BY clause instead of the DISTINCT.  You might wonder why? Here are the reasons: n        When you are using DISTINCT Clause, data would be spooled first and then duplicate rows would be eliminated. This is not a very efficient way unless you have less number of rows present in individual [+]