Netezza / PureData – How to build a multi table drop command from a select

Database Management
Database Management

How to Quick Drop Multiple Tables

occasionally, there is a need to quickly drop a list of tables and you don’t always want to write or generate each command individually in Aginity.  So, here is a quick example of how you can use a ‘Select’ SQL statement to generate a list of drop commands for you. Now, this approach assumes there is a common naming convention, so, you may need to adapt it to your needs.

An outline of the Drop Multiple Tables Process

Here is a quick summary of the steps to generate the drop statements from _V_Table:

  1. Build required Netezza SQL select; paying particular attention to the where clause criteria to exclude any unnecessary tables.
  2. Execute the SQL statement
  3. Copy from Aginity Results Tab without headers
  4. Past into new Aginity Query window
  5. validate that only the tables are in the list — No extras
  6. Click with the SQL Drop command list and Execute as a single batch

Example generate the drop statements

select  ‘Drop table ‘||tablename||’;’

from _V_TABLE

where tablename like ‘NZCC_TT_%’;

 

Related References

IBM Knowledge Center > PureData System for Analytics 7.2.1

IBM Netezza database user documentation > Netezza SQL command reference > Drop Table

Netezza / PureData – Table Describe SQL

Netezza Puredata Table Describe SQL
Netezza / Puredata Table Describe SQL

If you want to describe a PureData / Netezza table in SQL, it can be done, but Netezza doesn’t have a describe command.  Here is a quick SQL, which will give the basic structure of a table or a view.  Honestly, if you have Aginity Generating the DDL is fast and more informative, at least to me.  If you have permissions to access NZSQL you can also use the slash commands (e.g. \d).

Example Netezza Table Describe SQL

select  name as Table_name,

owner as Table_Owner,

Createdate as Table_Created_Date,

type as Table_Type,

Database as Database_Name,

schema as Database_Schema,

attnum as Field_Order,

attname as Field_Name,

format_type as Field_Type,

attnotnull as Field_Not_Null_Indicator,

attlen as Field_Length

from _v_relation_column

where

name='<<Table Name Here>>’

Order by attnum;

 

Related References

IBM Knowledge Center, PureData System for Analytics, Version 7.2.1

IBM Netezza database user documentation, Command-line options for nzsql, Internal slash options

IBM Knowledge Center, PureData System for Analytics, Version 7.2.1

IBM Netezza getting started tips, About the Netezza data warehouse appliance, Commands and queries, Basic Netezza SQL information, Commonly used nzsql internal slash commands

IBM Knowledge Center, PureData System for Analytics, Version 7.2.1

IBM Netezza database user documentation, Netezza SQL introduction, The nzsql command options, Slash options

 

 

Netezza / PureData – Substring Function On Specific Delimiter

SQL (Structured Query Language), Netezza / PureData - Substring Function On Specific Delimiter, substr
Netezza / PureData – Substring Function On Specific Delimiter

The function Substring (SUBSTR) in Netezza PureData provides the capability parse character type fields based on position within a character string.  However, it is possible, with a little creativity, to substring based on the position of a character in the string. This approach give more flexibility to the substring function and makes the substring more useful in many cases. This approach works fine with either the substring or substr functions.  In this example, I used the position example provide the numbers for the string command.

 

Example Substring SQL

Netezza PureData Substring Function On Specific Character In String, substring, substr
Netezza PureData Substring Function On Specific Character In String

 

Substring SQL Used In Example

select LOCATIONTEXT

,position(‘,’ in LOCATIONTEXT) as Comma_Postion_In_String

—without Adjustment

,SUBSTRING(LOCATIONTEXT,position(‘,’ in LOCATIONTEXT)) as Substring_On_Comma

—Adjusted to account for extra space

,SUBSTRING(LOCATIONTEXT,position(‘,’ in LOCATIONTEXT)+2) as Substring_On_Comma_Ajusted

,’==Breaking_Up_The_Sting==’ as Divider

— breaking up the string

,SUBSTRING(LOCATIONTEXT,1, position(‘ ‘ in LOCATIONTEXT)-1) as Beggining_of_String

,SUBSTRING(LOCATIONTEXT,position(‘ ‘ in LOCATIONTEXT)+1, position(‘ ‘ in LOCATIONTEXT)-1) as Middle_Of_String

,SUBSTRING(LOCATIONTEXT,position(‘,’ in LOCATIONTEXT)+2) as End_Of_String

 

FROM Blog.D_ZIPCODE

where STATE = ‘PR’

AND CITY = ‘REPTO ROBLES’

Related References

IBM Knowledge Center, PureData System for Analytics, Version 7.2.1

IBM Netezza database user documentation, Netezza SQL basics, Netezza SQL extensions, Character string functions

IBM Knowledge Center, PureData System for Analytics, Version 7.1.0

IBM Netezza Database User’s Guide, Netezza SQL basics, Functions and operators, Functions, Standard string functions

IBM Knowledge Center, PureData System for Analytics, Version 7.2.1

IBM Netezza database user documentation, Netezza SQL command reference, Functions

Aginity for Netezza – How to Display Query Results in a Single Row Grid

Aginity
Aginity

Displaying your Netezza query results in a grid can be useful.  Especially, when desiring to navigation left and right to see an entire rows data and to avoid the distraction of other rows being displayed on the screen. I use this capability in Aginity when I’m proofing code results and/or validating data in a table.

How To switch to the Single Row Grid

  • Execute your Query
  • When the results return, right click on the gray bar above your results (where you see the drag a column box
  • Choose the ‘Show a Single Row Grid’ Menu item

    Aginity Show Single Row Grid
    Aginity Show Single Row Grid

 

Grid View Change

  • Your result display will change from a horizontal row to a vertical grid as shown below
Aginity Single Row Grid Display
Aginity Single Row Grid Display

How to Navigate in the Single Row Grid

  • To navigate in the single row grid, use the buttons provided at the bottom of the results section.
Aginity Single Row Grid Navigation Buttons
Aginity Single Row Grid Navigation Buttons

Related References

 

PureData / Netezza – What date/time ranges are supported by Netezza?

SQL (Structured Query Language), Date/Time ranges supported by Netezza
Date/Time ranges supported by Netezza

Here is a synopsis of the temporal ranges ( date, time, and timestamp), which Netezza / PureData supports.

Temporal Type

Supported Ranges

Size In Bytes

Date

A month, day, and year. Values range from January 1, 0001, to December 31, 9999. 4 bytes

Time

An hour, minute, and second to six decimal places (microseconds). Values range from 00:00:00.000000 to 23:59:59.999999. 8 bytes

Related References

Temporal data types

PureData System for Analytics, PureData System for Analytics 7.2.1, IBM Netezza database user documentation, Netezza SQL basics, Data types, Temporal data types

Netezza date/time data type representations

PureData System for Analytics, PureData System for Analytics 7.2.1, IBM Netezza user-defined functions, Data type helper API reference, Temporal data type helper functions, Netezza date/time data type representations

Date/time functions

PureData System for Analytics, PureData System for Analytics 7.2.1, IBM Netezza database user documentation, Netezza SQL basics, Netezza SQL extensions, Date/time functions

Netezza / PureData – How to rebuild a Netezza view in Aginity

How To Generate View or table DDL in Aginity For Netezza PureData
How To Generate View or table DDL in Aginity For Netezza

 

Rebuilding Netezza view sometimes becomes necessary when the view’s source table have changed underneath the view.  Rebuilding a view can be done on Netezza or in Aginity. In Aginity, it is a simple process, assume your user has permissions to create or replace a view.  The process breaks down into just a few steps:

Generate the create / replace view SQL of the original view into the query window, if you don’t have it already

In the object browser:

  • Navigate to the Database and view you wish to rebuild
  • Select the view and right click
  • Select ‘Scripts’, then ‘DDL to Query window’

Make may updates to create / replace View SQL

  • This step is not always necessary, sometimes the changes which invalided the view did not actually impact the code of the view. If changes are necessary, make may updates to the SQL code.

Execute The code

  • This I usually do by choosing the ‘Execute as a single batch’ option.  Make sure the code executes successfully.

Verify the view

  • To verify the simply execute a select statement and make it executes without errors and/or warning.

Related References

 

Netezza / PureData – How to calculate months between two dates

Netezza, PureData, Months Between Two Dates, function, SQL, difference between two dates
Netezza PureData Months Between Two Dates

Recently, I had reason to during the months between two dates to test some data against business rule/requirement.  Pleasantly surprised I was to find that Netezza had an easy to use function ‘months_between’ function to calculate the difference.

 

The Months Between SQL Function syntax

The months_Between function uses two dates to perform the calculation.  Whether you want the output to be a positive or negative number determines the field order within the function.

  • For a positive number result, put the Newest Date Field first, separated by a comma, then Oldest Date Field
  • For a negative number result, just reverse the order putting the Oldest Date Field first, separated by a comma, then the Newest Date Field

The results will contain a decimal for the days of the month and you will need to round, based on your business requirements, to achieve a whole number.

 

SELECT months_between(<<DateField>>, <<DateField>>) as <<OutputFiledName>>,

from <<TableName>>;

 

Example Months Between SQL

SELECT months_between(current_date, Date(‘2017-01-01’)) as Difference_In_Months,

round(months_between(current_date, Date(‘2017-01-01’)) ) as Difference_In_Months_Rounded

from _v_dual;

 

Related References

Date/time functions

PureData System for Analytics, PureData System for Analytics 7.2.1, IBM Netezza database user documentation, Netezza SQL basics, Netezza SQL extensions, Date/time functions