Is there a way to get max function to ignore nulls within a column in sqlite?










0














Simply put, if I have a table with two columns (say people and height), I can use select max(height) from 'table' group by people and it will yield the largest height for any group of people_ignoring any nulls_.



If, however, I have a table with more columns (height_1, height_2, height_3, etc.) and I want to simply reproduce that table with a new column showing the maximum height (height_1, height_2, height_3, max_height), I would intuitvely like to put.



select
height_1,
height_2,
height_3,
max(height_1, height_2, height_3) as max_height
from 'table'


but used this way, max seems to behave differently, returning null if any of the arguments are null.



Is there some form of use which will get it to behave the way it does when aggregating a column, and ignore null values?, even when aggregating single values across a range of columns?










share|improve this question




























    0














    Simply put, if I have a table with two columns (say people and height), I can use select max(height) from 'table' group by people and it will yield the largest height for any group of people_ignoring any nulls_.



    If, however, I have a table with more columns (height_1, height_2, height_3, etc.) and I want to simply reproduce that table with a new column showing the maximum height (height_1, height_2, height_3, max_height), I would intuitvely like to put.



    select
    height_1,
    height_2,
    height_3,
    max(height_1, height_2, height_3) as max_height
    from 'table'


    but used this way, max seems to behave differently, returning null if any of the arguments are null.



    Is there some form of use which will get it to behave the way it does when aggregating a column, and ignore null values?, even when aggregating single values across a range of columns?










    share|improve this question


























      0












      0








      0







      Simply put, if I have a table with two columns (say people and height), I can use select max(height) from 'table' group by people and it will yield the largest height for any group of people_ignoring any nulls_.



      If, however, I have a table with more columns (height_1, height_2, height_3, etc.) and I want to simply reproduce that table with a new column showing the maximum height (height_1, height_2, height_3, max_height), I would intuitvely like to put.



      select
      height_1,
      height_2,
      height_3,
      max(height_1, height_2, height_3) as max_height
      from 'table'


      but used this way, max seems to behave differently, returning null if any of the arguments are null.



      Is there some form of use which will get it to behave the way it does when aggregating a column, and ignore null values?, even when aggregating single values across a range of columns?










      share|improve this question















      Simply put, if I have a table with two columns (say people and height), I can use select max(height) from 'table' group by people and it will yield the largest height for any group of people_ignoring any nulls_.



      If, however, I have a table with more columns (height_1, height_2, height_3, etc.) and I want to simply reproduce that table with a new column showing the maximum height (height_1, height_2, height_3, max_height), I would intuitvely like to put.



      select
      height_1,
      height_2,
      height_3,
      max(height_1, height_2, height_3) as max_height
      from 'table'


      but used this way, max seems to behave differently, returning null if any of the arguments are null.



      Is there some form of use which will get it to behave the way it does when aggregating a column, and ignore null values?, even when aggregating single values across a range of columns?







      sqlite






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Nov 12 at 7:11









      a_horse_with_no_name

      291k46444537




      291k46444537










      asked Nov 12 at 7:05









      Isaacson

      946




      946






















          1 Answer
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          1














          You can use something like:



          SELECT height_1
          , height_2
          , height_3
          , max(ifnull(height_1, 0), ifnull(height_2, 0), ifnull(height_3, 0)) AS max_height
          FROM "table"





          share|improve this answer




















          • Thanks. Follow up question, is there a way to do the same with min()? the problem here being that replacing nulls with '0' would give a false impression from the set 2,4,null,5,null,7 that the minimum was 0 when in fact the minimum non-null value is 2.
            – Isaacson
            Nov 12 at 7:51






          • 1




            @Isaacson Just use a larger-than-possible number for min(), and a smaller-than-possible one for max() (And check if your select returned that number to handle cases of all values being null).
            – Shawn
            Nov 12 at 8:05










          • That's perfect, thanks.
            – Isaacson
            Nov 12 at 8:10










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          1 Answer
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          oldest

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          1 Answer
          1






          active

          oldest

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          active

          oldest

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          active

          oldest

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          1














          You can use something like:



          SELECT height_1
          , height_2
          , height_3
          , max(ifnull(height_1, 0), ifnull(height_2, 0), ifnull(height_3, 0)) AS max_height
          FROM "table"





          share|improve this answer




















          • Thanks. Follow up question, is there a way to do the same with min()? the problem here being that replacing nulls with '0' would give a false impression from the set 2,4,null,5,null,7 that the minimum was 0 when in fact the minimum non-null value is 2.
            – Isaacson
            Nov 12 at 7:51






          • 1




            @Isaacson Just use a larger-than-possible number for min(), and a smaller-than-possible one for max() (And check if your select returned that number to handle cases of all values being null).
            – Shawn
            Nov 12 at 8:05










          • That's perfect, thanks.
            – Isaacson
            Nov 12 at 8:10















          1














          You can use something like:



          SELECT height_1
          , height_2
          , height_3
          , max(ifnull(height_1, 0), ifnull(height_2, 0), ifnull(height_3, 0)) AS max_height
          FROM "table"





          share|improve this answer




















          • Thanks. Follow up question, is there a way to do the same with min()? the problem here being that replacing nulls with '0' would give a false impression from the set 2,4,null,5,null,7 that the minimum was 0 when in fact the minimum non-null value is 2.
            – Isaacson
            Nov 12 at 7:51






          • 1




            @Isaacson Just use a larger-than-possible number for min(), and a smaller-than-possible one for max() (And check if your select returned that number to handle cases of all values being null).
            – Shawn
            Nov 12 at 8:05










          • That's perfect, thanks.
            – Isaacson
            Nov 12 at 8:10













          1












          1








          1






          You can use something like:



          SELECT height_1
          , height_2
          , height_3
          , max(ifnull(height_1, 0), ifnull(height_2, 0), ifnull(height_3, 0)) AS max_height
          FROM "table"





          share|improve this answer












          You can use something like:



          SELECT height_1
          , height_2
          , height_3
          , max(ifnull(height_1, 0), ifnull(height_2, 0), ifnull(height_3, 0)) AS max_height
          FROM "table"






          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 12 at 7:29









          Shawn

          3,4531613




          3,4531613











          • Thanks. Follow up question, is there a way to do the same with min()? the problem here being that replacing nulls with '0' would give a false impression from the set 2,4,null,5,null,7 that the minimum was 0 when in fact the minimum non-null value is 2.
            – Isaacson
            Nov 12 at 7:51






          • 1




            @Isaacson Just use a larger-than-possible number for min(), and a smaller-than-possible one for max() (And check if your select returned that number to handle cases of all values being null).
            – Shawn
            Nov 12 at 8:05










          • That's perfect, thanks.
            – Isaacson
            Nov 12 at 8:10
















          • Thanks. Follow up question, is there a way to do the same with min()? the problem here being that replacing nulls with '0' would give a false impression from the set 2,4,null,5,null,7 that the minimum was 0 when in fact the minimum non-null value is 2.
            – Isaacson
            Nov 12 at 7:51






          • 1




            @Isaacson Just use a larger-than-possible number for min(), and a smaller-than-possible one for max() (And check if your select returned that number to handle cases of all values being null).
            – Shawn
            Nov 12 at 8:05










          • That's perfect, thanks.
            – Isaacson
            Nov 12 at 8:10















          Thanks. Follow up question, is there a way to do the same with min()? the problem here being that replacing nulls with '0' would give a false impression from the set 2,4,null,5,null,7 that the minimum was 0 when in fact the minimum non-null value is 2.
          – Isaacson
          Nov 12 at 7:51




          Thanks. Follow up question, is there a way to do the same with min()? the problem here being that replacing nulls with '0' would give a false impression from the set 2,4,null,5,null,7 that the minimum was 0 when in fact the minimum non-null value is 2.
          – Isaacson
          Nov 12 at 7:51




          1




          1




          @Isaacson Just use a larger-than-possible number for min(), and a smaller-than-possible one for max() (And check if your select returned that number to handle cases of all values being null).
          – Shawn
          Nov 12 at 8:05




          @Isaacson Just use a larger-than-possible number for min(), and a smaller-than-possible one for max() (And check if your select returned that number to handle cases of all values being null).
          – Shawn
          Nov 12 at 8:05












          That's perfect, thanks.
          – Isaacson
          Nov 12 at 8:10




          That's perfect, thanks.
          – Isaacson
          Nov 12 at 8:10

















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