title: SQL query to update a column(multiple rows) in a table from another table
body: <p>Suppose there is a column in a table with NULL values with 'n' rows. Now I want to update that column with the values from another table column with same number of rows (n). How?</p>
  
  <p>Edit:
  My tables are: A and B, A has call_id, operator with 10 rows. call_id is primary key there. Now, B has call_id, calllog_id and duration as columns where call_id is FK and calllog_id is PK, In B, call_id is null in every row (same 10 rows). Now i want to copy the 10 row values of A.call_id into B.call_id</p>