Friday, May 29, 2015

What you need to know about DBC in Teradata?

As a database developer you may think DBC* is for database administrator to care about, not for you as a database developer.

However, knowing about DBC can save your time when it come to query like. e.g. you need to  know all the tables in your database? or Column names in a table or existing views in a database. Sometimes, you may need to anonymous some of the columns in a few tables that you need to do using DBC.

You could say, I can see all table names by browsing the database table and can copy and paste names of all the tables. Yes, you can do it but that is time consumable and manual process. Would not it be nice if you can get all the table names by writing two lines of code.

Lets say, you want to find out all the tables name in your database then SQL will look like below:

Select * from dbc.tables where tablekind='T' and databasename='STUDENT103'

which will return below result (part of the full result):
Fig 1: Tables list of the database

To find out the view names from the database then SQL will look like below:

Select * from dbc.tables where tablekind='V' and databasename='STUDENT103'

Part of the result set look like below:
Fig 2: View list of the database(database contains only one view)

To get all the column names of a table of database, you need to write below SQL:

SELECT DatabaseName,TableName,ColumnName
FROM DBC.Columns
WHERE DatabaseName='STUDENT103'

Result of the above code will look like below:

Fig 3: List of columns in a table

By using DBC you can get not only column, table, view names but also more attributes like who created the table or view, when it's created and so on.

Note: DBC is the superuser on Teradata database

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