Count the Null columns in a row in SQL

Question

I was wondering about the possibility to count the null columns of row in SQL, I have a table Customer that has nullable values, simply I want a query that return an int of

Answer 1

For ORACLE-DBMS only.

You can use the NVL2 function:

NVL2( string1, value_if_not_null, value_if_null )

Here is a select with a similiar approach as Michael Berkowski suggested:

SELECT (NVL2(col1, 0, 1) 
        + NVL2(col2, 0, 1)
        + NVL2(col3, 0, 1)
        ...
        ...
        + NVL2(col10, 0, 1)
        ) AS sum_of_nulls
FROM table
WHERE Customer=some_cust_id

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A more generic approach would be to write a PL/SQL-block and use dynamic SQL. You have to build a SELECT string with the NVL2 method from above for every column in the all_tab_columns of a specific table.