title: SQL: How to update an empty column with pre-defined set of values
body: <p>I have a table with, let's say, 100 records. The table has two columns. The first column (A) has unique values. The second column (B) has NULL values</p>
  
  <p>For 4 elements from column A I'd like to associate some earlier defined values, and they are unique as well.</p>
  
  <p><img src="https://i.stack.imgur.com/PKNjx.png" alt="Example"></p>
  
  <p>I don't care about which value from column B will be associated with the value from column A. I'd like to associate 4 unique values with another 4 unique values. Basically, like I'd cut and paste a block of values from one column to another in excel.</p>
  
  <p>How can I do it without using cursors?</p>
  
  <p>I'd like to use one Update statement for ALL rows instead one Update statement for EVERY row as I do now.</p>