5.4.5 - Null Replacement - Teradata Warehouse Miner

In-Database Analytic Functions User Guide

Teradata Warehouse Miner
February 2018
User Guide


NULL value replacement is offered as a transformation function. A literal value, the mean, median, mode, or an imputed value joined from another table can be used as the replacement value. The median value can be requested with or without averaging of two middle values when there is an even number of values.

Literal value replacement is supported for numeric, character, and date data types. Mean value replacement is supported for columns of numeric type or date type. Median without averaging, mode, and imputed value replacement are valid for any supported type. Median with averaging is supported only for numeric and date type.


call twm. td_analyze('vartran','database=twm_source;tablename=twm_customer;keycolumns=cust_id;General Parameters;nullreplacement={nullstyle (imputed,twm_customer_analysis),columns (income)};');

Required Parameters

Controls the name of the output (transformed) column and its data type. The columns parameter is required by all transformations except Derive. A separate transformation is performed for each column in the list. If a column name is followed by a forward slash and a name, the name after the slash becomes the name of the transformed column in the resultant output table. Otherwise the column name is used as the output column name.
For the Derive transformation, the outputname parameter controls the naming of the transformed output column.
The database containing the input table.
When null replacement is requested, either via a Null Replacement transformation or in combination with a Bin Code, Derive, Design Code, Recode, Rescale, Sigmoid, or Z Score transformation, the keycolumns parameter must be specified. The column or columns listed must form a unique key into the input and output table of the transformation.
Identifies the type of transformation being performed.
Data types supported by various nullstyle parameters are:
Data Type Description Example
literal,value numeric, character, and date nullstyle (literal,value)
mean numeric and date nullstyle (mean)
median numeric and date nullstyle (median)
medianwithoutaveraging any supported data type nullstyle (medianwithoutaveraging)
mode any supported date type nullstyle (mode)
imputed,table any supported data type nullstyle (imputed,tablename)

If date values are entered, the keyword DATE must precede the date value, which should not be enclosed in single quotes.

The input table to build a predictive model from.
Required to run a variable transformation. Enclose the 'vartran' parameter in single quotes.

Optional Parameters

For all transformation types, the datatype casts the column to a desired database data type provided it is compatible with the transformed data.
Allowed output types include:
  • byteint
  • char
  • date
  • decimal
  • float
  • integer
  • smallint
  • time
  • timestamp
  • varchar
  • bigint
  • number
When true, requests a mirrored copy of the output table in the Teradata Database when outputstyle=table.
When true, the SQL for the requested transformations is returned as a result set but not executed. When not specified or set to false, the SQL is executed but not returned.
When true, requests the output table contain the index columns when outputstyle=table.
When true, requests the output table contain a unique primary index when outputstyle=table.

Requests the generated SQL contain the given locking clause in the appropriate location depending on the output style.

An example of a locking clause when the output style defaults to select is:

LOCKING mydb.mytable FOR ACCESS;

When true, requests an output table that can contain duplicate rows when outputstyle=table.
When true, requests the output table contain no index columns when outputstyle=table.
The database containing the resulting output table when outputstyle=table or view.
Allowed output styles are:
  • select
  • table
  • view
If outputstyle is not specified, the function generates a SELECT statement and does not create a table or view.
The name of the output table when outputstyle=table or view.

When overwrite is set to true (default), the output tables are dropped before creating new ones.

Requests the generated SQL containing the given WHERE clause in appropriate places in the generated SQL. This is independent of the output style requested.


These examples demonstrate the Null Replacement transformation. To execute the provided examples, the td_analyze function must be installed in a database called twm and the Teradata Warehouse Miner tutorial data must be installed in the twm_source database.

The first example operates on numeric data.

call twm.td_analyze('vartran','database=twm_source;tablename=twm_customer;keycolumns=cust_id;nullreplacement={nullstyle(literal,0),columns(age,income/inc)}{nullstyle(mean),columns(age/age1)}{nullstyle(median),columns(age/age2)}{nullstyle(medianwithoutaveraging),columns(age/age3)}{nullstyle(mode),columns(age/age4)}{nullstyle(imputed,twm_customer_analysis),columns(income)};');
This example operates on date and character type data.
call twm.td_analyze('vartran','database=twm_source;tablename=twm_credit_acct;keycolumns=cust_id;nullreplacement={nullstyle(literal,DATE 1995-12-23),columns(acct_end_date/date1)}{nullstyle(literal,U),columns(account_active/char1)}{nullstyle(mean),columns(acct_end_date/date2)}{nullstyle(median),columns(acct_end_date/date2A)}{nullstyle(medianwithoutaveraging),columns(acct_end_date/date3)}{nullstyle(mode),columns(acct_end_date/date4)}{nullstyle(imputed,twm_checking_acct),columns(acct_end_date/date5)}{nullstyle(medianwithoutaveraging),columns(account_active/char2)}{nullstyle(mode),columns(account_active/char3)}{nullstyle(imputed,twm_checking_acct),columns(account_active/char4)};');