Column Mapping

Column mapping is the process of deriving the schema of the target dataset from the source dataset, enabling you to select all columns, select some columns, or exclude columns from the source dataset, based on the needs of the business user.

You can choose to:

• Select all columns
• Select some columns
• Exclude columns

Select all columns

If you select all the columns from the source table or derived dataset, the column properties of the source dataset are inherited by the target dataset. The target dataset contains all the columns from the source or derived dataset with no modifications to the schema.

Description of the illustration dasrg-colmapping-all.png

IMPORT SOURCE CUSTOMERS
DEFINE DATASET CUSTOMERS_D 
   ROWSOURCE CUSTOMERS;
   THIS = CUSTOMERS;
END

In this example, these eight columns from the source table CUSTOMERS are in the target table CUSTOMERS_D with no modifications to their properties:

• CUST_ID
• CUST_FIRST_NAME
• CUST_LAST_NAME
• CUST_GENDER
• CUST_YEAR_OF_BIRTH
• CUST_MARITAL_STATUS
• CUST_CITY
• COUNTRY_ID

You can also simplify the code in the following way:

IMPORT SOURCE CUSTOMERS
DEFINE DATASET CUSTOMERS_D FROM CUSTOMERS END

Select some columns

You can choose to bring in a subset of columns from the schema of the source or derived dataset.

Description of the illustration dasrg-colmapping-some.png

IMPORT SOURCE CUSTOMERS
 DEFINE DATASET CUSTOMERS_D 
  ROWSOURCE CUSTOMERS;
  THIS = CUSTOMERS[CUST_ID,CUST_FIRST_NAME,CUST_LAST_NAME,
                   CUST_YEAR_OF_BIRTH,COUNTRY_ID,CUST_MARITAL_STATUS];
 END

In this example, only these selected columns from the source table CUSTOMERS form the schema in the target dataset CUSTOMERS_D:

• CUST_ID
• CUST_FIRST_NAME
• CUST_LAST_NAME
• CUST_YEAR_OF_BIRTH
• COUNTRY_ID
• CUST_MARITAL_STATUS

You can also simplify the code in the following way:

IMPORT SOURCE CUSTOMERS
DEFINE DATASET CUSTOMERS_D FROM CUSTOMERS[CUST_ID,CUST_FIRST_NAME,
CUST_LAST_NAME,CUST_YEAR_OF_BIRTH,COUNTRY_ID, CUST_MARITAL_STATUS] END

Exclude columns

If you want to exclude certain columns from the source table or derived dataset, you can use the EXCLUDE keyword. The remaining columns remain in the target dataset.

Description of the illustration dasrg-colmapping-exclude.png

IMPORT SOURCE CUSTOMERS
 DEFINE DATASET CUSTOMERS_D 
   ROWSOURCE CUSTOMERS;
   THIS = CUSTOMERS EXCLUDE [CUST_GENDER,CUST_MARITAL_STATUS];
 END

You can also simplify the code in the following way:

IMPORT SOURCE CUSTOMERS
DEFINE DATASET CUSTOMERS_D FROM CUSTOMERS EXCLUDE [CUST_GENDER,CUST_MARITAL_STATUS] END