Does SAS write over initial defined variables if it is defined a second time?

[SAS93]

I don't recall having learned this "directly", but experience seems to point that it does. I just wanted to clarification on it. 

I have been using SAS to group a series of Y/N survey response variables into a single categorical variable for defining a respondent's insurance status.

I've been doing this for a single set of years (example: Set 1 = 2012 - 2014, Set 2 = 2015 - 2017). Each set has mostly the same variable names, except Set 1 has a few additional variables that Set 2 doesn't have, and one that is named differently. 

So:

/* Set 1 */

If work in (1) or comp in (1) then insurance = 1; *work or partner's work;

If medic in (1) or gov in (1) then insurance = 2; *Medicaid or other government-funded;

if other in (1) then insurance = 3; *other;

if none in (1) then insurance = 4; *none;

/* Set 2 */

If work4 in (1) or hcech in (1) then insurance = 1; *work or healthcare exchange program;

If medic in (1)  then insurance = 2; *Medicaid or other government-funded;

if other in (1) then insurance = 3; *other;

if none in (1) then insurance = 4; *none;

I ask because--when run the Set 1 and Set 2 datasets separately with their respective codes, I always get the same numbers for Set 2 regardless of running separately or combined with Set 1, but Set 1 is always different depending on how I run it. I just wanted to confirm that this "overwriting" is what was happening. 

[Kurt_Bremser]

Please post your complete data step code, so we know how you read the datasets.

[SAS93]

Data instatus;

Set ins.set1 ins.set2;

* Set 1 = 2012 - 2014;

* Set 2 = 2015 - 2017;

* YY_STAT  = survey year; char var, YYYY format;

/* Status for Set 1 */

If work in (1) or comp in (1) then insurance = 1; *work or partner's work;

If medic in (1) or gov in (1) then insurance = 2; *Medicaid or other government-funded;

if other in (1) then insurance = 3; *other;

if none in (1) then insurance = 4; *none;

/* Set 2 */

If work4 in (1) or hcech in (1) then insurance = 1; *work or HSA program;

If medic in (1)  then insurance = 2; *Medicaid or other government-funded;

if other in (1) then insurance = 3; *other;

if none in (1) then insurance = 4; *none;

Run;

[Kurt_Bremser]

The variable insurance exists only once in the PDV, so all those statements will have an effect on it.

If medic and other are both 1, then insurance = 3 will "overwrite" insurance = 2, simply because the test for other comes after the test for medic.