At present, there are about 400 million data in Table A, and the key fields are the mobile phone number and the C field. There are duplicates in the mobile phone number. Then compare each number found in Table A with the mobile phone number field in Table B. If the mobile phone number is duplicates, the C field will be updated, and if it is not, it will be added to Table B
Current practice: write a while loop, each loop from table A 3000 data, 3000 data in the loop, get each data look up table B for new or modified in turn
This method is too inefficient to process data. The for loop needs to check and change the library every time. Is there a better way to solve this problem? Please give advice or comments