sql - Calculating Number of Columns that have no Null value -

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i want make table following

| id | sibling1 |   sibling2 |   sibling 3  | total_siblings | ______________________________________________________________ | 1  |  tom     |    lisa    |    null      |       2        |  ______________________________________________________________ | 2  |  bart    |    jason   |    nelson    |       3        | ______________________________________________________________ | 3  |  george  |    null    |    null      |       1        | ______________________________________________________________ | 4  |  null    |    null    |    null      |       0        |

for sibling1, sibling2, sibling3: nvarchar(50) (can't change requirement).

my concern how can calculate value total_siblings display number of siblings above, using sql? attempted use (sibling1 + sibling 2) not display result want.

cheers

a query trick.

select id,sibling1,sibling2,sibling3 ,count(sibling1)+count(sibling2)+count(sibling3) total mytable group id

a little explanation required here. count field name count number of non-null values. since grouping id, ever return 0 or 1. now, if you're using other mysql, you'll have substitute 

group id

for

group id,sibling1,sibling2,sibling3

because other databases require specify columns don't contain aggregate function in group section.

also, aside, may want consider changing database schema store siblings in table, each person can have number of siblings.


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