Cleaning

Question 1

Records where x is the same as y

Answer 1

Select Count (*) From (…) Where x=y

Question 2

Records where x is blank

Answer 2

Select Count(*) From (…) Where x is null

Question 3

Records where there are duplicate copies of x

Answer 3

Select x, count() From(…) Group by x Having Count () > 1

Question 4

Update an incorrect value of an attribute

Answer 4

Update (…) Set attribute1 = ‘…’ where attribute2 = ‘…’

Question 5

Check if there are illegal invalid entries

Answer 5

Select * from (…) where x not in (select x from (…))

Question 6

is empty, is not within and is similar to

Answer 6

aaa like ‘xxx%’ and aaa not in and aaa is null