How do I enter data in cells that were left blank

[DK13]

I have a data set with a column that indicates poor sleep, but instead of filling in all of the cells, they only indicated "y" if the patient had poor sleep. 

How can I fill in the blank cells so they contain "n"?

I tried making a new column:

DATA polphar.Polypharm_DataV3;
SET polyphar.polypharm_data;
IF poor_sleep= "." then poor_sleepYN= "N";
IF poor_sleep= "y" THEN poor_sleepYN= "Y";
RUN;

But it keeps giving me this error: ERROR: Libref POLPHAR is not assigned.

I am using SAS University Edition. 

[Reeza]

if missing(poor_sleep) then poor_sleepYN="N";
else poor_sleepYN = upcase(poor_sleepYN);

[Reeza · Accepted solution]

Actually, you just have a typo, not the y in one and not the other.

DATA polphar.Polypharm_DataV3;
SET polyphar.polypharm_data;

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@DK13 wrote:

I have a data set with a column that indicates poor sleep, but instead of filling in all of the cells, they only indicated "y" if the patient had poor sleep. 

How can I fill in the blank cells so they contain "n"?

I tried making a new column:

DATA polphar.Polypharm_DataV3;
SET polyphar.polypharm_data;
IF poor_sleep= "." then poor_sleepYN= "N";
IF poor_sleep= "y" THEN poor_sleepYN= "Y";
RUN;

But it keeps giving me this error: ERROR: Libref POLPHAR is not assigned.

I am using SAS University Edition. 

---

[DK13]

Good catch! Thanks!