Query regarding current_time and checksum... plz help
I am very new to teradata. I am using mainframe+teradata and also thru sql assistant. Today I observed something for which I want an explanation. two problems-- Prob 1. I had a table tablea, where a field operational_tim was declared as integer. But I was supposed to change this column to the below format. OPERATIONAL_TIM TIME(6) NOT NULL DEFAULT CURRENT_TIME(0). The table has data. So, I did below things ALTER TABLEA DROP OPERATIONAL_TIM ALTER TABLEA ADD OPERATIONAL_TIM TIME(6) NOT NULL DEFAULT CURRENT_TIME(0)
First alter ran fine but the second one gave me error as: incompatible default value. Plz help me regarding this
Prob 2. I created one table TableB with one column as OPERATIONAL_TIM TIME(6) NOT NULL DEFAULT CURRENT_TIME(0) got the same error as incompatible default value and then with a trial and error,when defined the table with CHECKSUM=DEFAULT option the table got created succesfully. Can anybody explain why with checksum=default option it got created successfully?