How to select the comparison of two columns as one column in Oracle

Question

I cannot figure out how to add a column to my SELECT query indicating whether two columns contain the same data in Oracle   I would like to write a query like   select column1  column2  column1 column2 from table   and  if I have this table    --------- ---------    column1   column2    --------- ---------    value1    value1      value2    value3      value4    value4     --------- ---------    get a result like    --------- --------- -----------------    column1   column2   column1 column2    --------- --------- -----------------    value1    value1    true                value2    value3    false               value4    value4    true               --------- --------- -----------------    What is the correct syntax to do this

User · Answer

select column1  coulumn2  case when colum1 column2 then  true  else  false  end from table    HTH

User · Answer

I stopped using DECODE several years ago because it is non-portable  Also  it is less flexible and less readable than a CASE WHEN    However  there is one neat  trick  you can do with decode because of how it deals with NULL  In decode  NULL is equal to NULL  That can be exploited to tell whether two columns are different as below   select a  b  decode a  b   true    false   as same   from t        A       B  SAME ------  ------  -----      1       1  true      1       0  false      1          false   null    null  true

User · Answer

If you want to consider null values equality too  try the following  select column1  column2      case       when column1 is NULL and column2 is NULL then  true          when column1 column2 then  true         else  false      end  from table

[sql] How to select the comparison of two columns as one column in Oracle

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