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Don Burleson Blog 







Suppressing NULL Column Values in SQL Output

Expert Oracle Database Tips by Donald BurlesonNovember 29, 2015

Question:  I am running a SQL query and I get improperly formatted NULL output, displayed as back to back double quotes:

 1 51 10  ""
 1 51 10  "JACK"
 2 52 10  "BOB"
 2 52 10  ""
 3 51 11  "BILL"
 3 51 11  ""
 4 52 999 ""

How can I remove these double quotes from my SQL output?

Answer:  There are many ways to remove unwanted NULL values in SQL output:

  •  NVL

  • SQL*Plus column format command

  • decode or case statements

  • where clause filtering

I would start by experimenting with the NVL operator to suppress a NULL value.  The Oracle NULL Value (NVL) SQL operator is a great way to substitute NULL values with numeric values or a blank string in Oracle SQL statements.

The most common use for the NULL value (NVL) clause is to prevent mathematical operations from aborting with a zero divisor. Here are examples of the NVL SQL operator:

select nvl(b.buffer_gets,0) - NVL replaces a NULL value with a zero
select nvl(current_status, "Not disclosed") - NVL replaces a NULL value with a string

As you can see, the NVL function replaces a NULL with whatever value you desire.

If your output is in SQL*Plus, you can use the column and format command to suppress the display of any column.

I'm not positive, but you may be able to use decode to change the NULL's to a blank.

Lastly, you can suppress a NULL value by using a where clause if doing an aggregate:

where mycol is not null or length(trim(mycol)) > 0

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