Question

tableA contains {id, fromPos not null, toPos}

• fromPos and toPos denotes a range of values for a particular row
• toPos is a nullable field

and has the following values

tableA (1, 5)     // means any position greater than or equal to 5
tableA (2, 5, 10) // means any position between 5 and 10 (inclusive)
tableA (3, 6) 
tableA (4, 7, 9)

• How to fetch all entries whose position is 7. It should return the id’s (1,2,3,4)
• How to fetch all entries whose position is 5. It should return the id’s (1,2)
• How to fetch all entries whose position is 8. It should return the id’s (1,2,3,4)

Answer 1

For a given target value, X, the query appears to be:

SELECT id
  FROM TableA
 WHERE fromPos <= X
   AND (toPos >= X OR toPos IS NULL);