Hi ballardw, Thank you for your help. It kinds worked, but did not help to get exactly I wanted. The story is...every month has a table which contains about 612k observations, but it did not have "month" indicator, and I need to add one, so I know which month the data was pulled from. The library name is MC201611, MC201610.....MC201301(there are more, till 200801). What I wanted was to add a column to indicate the month, so when I pull one observation, I know which month it was from. Hope this will clear the confusion before. Ro
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