Question: I'm not sure how to resolve this error:

*Procedure or Function 'sp\_executesql' expects parameter '@statement', which was not supplied.*

for this query:

```
DECLARE @a INT 
DECLARE @b VARCHAR 
SET @a = 1

WHILE @a < 30
BEGIN
set @b = @a  
exec sp_executesql update source_temp set pmt_90_day = pmt_90_day + convert(money,'trans_total_'+@b)+N'
    N'where convert(datetime,'effective_date_'+@b)+N' <= dateadd(day,90,ORSA_CHARGE_OFF_DATE)
    and DRC_FLAG_'+@b = 'C'''

SET @a = @a + 1
END

```

Also, can you help me understand the proper usage of N' and if its done correctly in this statement.

Thanks for your assistance.

Answer: 
For the US, you can check out the [HIPAA guide](http://www.hipaaguide.net/) for web programmers.
HL7 is what you need.

Some links:

<http://aurora.regenstrief.org/security/>

<http://www.hl7.org.au/docs/HL7-Sec.htm>