Question

I have the following table :

 X    Y    Z     T
 __________________
 A          2             
 B          5                       Z is UNIQUE
 C          8
 A          3
 B          6                     
 A          4
 C          1

I want reduce the table to the following one according to Z values;

 X    Y    Z     T
 __________________

 A         2           
 A         3                   
 A         4
 B         5
 B         6 

how can I want construct table as follows ?

difference btw 3 and 2 is 1, and PK, i.e X, are same so take “A 2” and “A 3”

difference btw 4 and 3 is 1, and PK, i.e X, are same so take “A 4” and “A 3”

difference btw 6 and 5 is 1, and PK, i.e X, are same so take “B 6” and “B 5”

how can I do that ?

Answer 1

SELECT a.*
FROM TableX AS a
WHERE EXISTS
      ( SELECT *
        FROM TABleX AS b
        WHERE b.X = a.X
          AND ( b.Z = a.Z + 1
             OR b.Z = a.Z - 1
              )
      )