Oracle: Finding Columns with only null values

Question

I have a table with a lot of columns and a type column.

Some columns seem to be always empty for a specific type.

I want to create a view for each type and o

Answer 1

I think you can solve this using metaprogramming. Use a cursor to loop through each type and column, and use 'not exists' to check if the column is empty. For example:

CREATE TABLE result_table (type VARCHAR(50), column VARCHAR(50))

CURSOR c IS
    SELECT COLUMN_NAME FROM ALL_TAB_COLS WHERE TABLE_NAME = &table_name;

CURSOR ct IS
    SELECT DISTINCT type_name FROM &table_name;

BEGIN

FOR t in ct
LOOP
    FOR r in c
    LOOP
        --If you're confused about how this works, replace 'EXECUTE IMMEDIATE'
        --with print or something and look at the output
        EXECUTE IMMEDIATE
            'INSERT INTO result_table SELECT ''' ||
                t.type_name || ''', ''' || r.COLUMN_NAME ||
                ''' FROM DUAL WHERE NOT EXISTS (SELECT 1 FROM ' || 
                &table_name || ' WHERE t.type_name = ''' || t.type_name ||
                ''' AND ' || r.COLUMN_NAME || ' IS NOT NULL);';
    END LOOP
END LOOP

SELECT * FROM result_table

Apologies if there's a mistake in the syntax somewhere, I have nothing to check this on.