replace null values with content from another column based on condition

[dorothybl]

I have 20 million rows loaded. I want to replace null values from Column B. The value to be replaced will depends on what value is indicated on the column a.

Example:

For null values,

1 = W

4 = E

and so on..

Please take note that null values are many. And the null values is not limited to two only. 

Just new to power bi desktop. please guide me. How should I do this?

[Ashish_Mathur]

Hi,

Create a lookup table and then join your existing Table with the look up Table.

[dorothybl]

apologies but i cannot figure out how should i make a look up table for this.

i have 20 millions rows.

[Ashish_Mathur]

Hi,

Since there are multiple null values, you will have to tell the software what should go in place of each such cell.  So there will have to be an input table of 2 columns with column 1 values from your existing table.  The second column should be the result you want.

[v-jiascu-msft]

Hi @dorothybl,

Where are all the replacements? In other words, where is "1 = W 4 = E" from? It could be like this one.

Result_Column =
IF (
    ISBLANK ( [Column B] ),
    LOOKUPVALUE (
        'replacementsTable'[result],
        'replacementsTable'[Column A], [Column A]
    ),
    [Column B]
)

Best Regards,

[dorothybl]

Hi @v-jiascu-msft

it will come from a separate table called "FixTable" and here is the sample data inside it. Data in the "FixTable" are only those numbers with blank letters.

I tried using your code but it did not work. can you check what was wrong with it?

Result_Column =
IF (
    ISBLANK ( [Column B] ),
    LOOKUPVALUE (
        'FixTable'[Letter],
        'FixTable'[Number], [Column A]
    ),
    [Column B]
)

[v-jiascu-msft · Accepted solution]

Hi @dorothybl,

Did you get any error messages? Or it returns wrong results? 

Maybe this one.

Result_Column =
IF (
    [Column B] = blank(),
    LOOKUPVALUE (
        'FixTable'[Letter],
        'FixTable'[Number], [Column A]
    ),
    [Column B]
)

Best Regards,

[dorothybl]

hey it works! thanks @v-jiascu-msft