How to do it...

1. Connect to Teradata Database using SQLA or Studio.
2. Let's try to find pre-paid and post-paid customers based on the connection_type code column; the connection_type=1 would be Pre-paid and connection_type=2 would be post-paid:

/*Select for CASE*/
SELECT   
 cust_id,
 Cust_Add,
  CASE WHEN Connection_type=1 THEN 'Pre-paid'
      WHEN Connection_type=2 THEN 'Post-paid'
 ELSE 'Not Sure'
 END AS Connection_type
 FROM CUST_Type;

1. Let's check the output of the following:

cust_id         Cust_add         Connection_type
 -----------    -----------         ----------- 
     10         bal                 Pre-paid
     21         86 court            Post-paid
     31         62 st               Post-paid
     32         21 rd               Pre-paid
     102        271 main            Post-paid
     082        10sroad               Pre-paid
     23        jh1-0s                 Not Sure