I'm trying to inner join two tables imported from excel both tables have the same SIN data set

[AlonzoT]

[Tom]

Pasting text as pictures makes it very hard to read.

You define table aliases using different two letter abbreviations than the aliases you use in the WHERE clause.

[A_Kh]

Your ON clause has a typo: It shouldn't be on sc.SIN=ct.SIN, but ON ST.SIN=CT.SIN

[Reeza]

FYI - the fact that the data from Excel is really only minimal relevant. Once you've imported it, it's a SAS data set. You should take the time to review this to make sure it's occurred correctly, ie variable names, labels and types are correct and values were read in correctly.