Hello Guys!I am doing a master thesis but i have a question related to R coding.

I am doing some Geometadb tutorial to understand how it works, and i found this code line that i dont understand totally: 

 rs <- dbGetQuery(con,paste("select gpl.bioc_package,gsm.gpl,",
                            "gsm,gsm.supplementary_file",
                            "from gsm join gpl on gsm.gpl=gpl.gpl",
                            "where gpl.manufacturer='Affymetrix'",
                            "and gsm.supplementary_file like '%CEL.gz' ")) 

I dont understand the meaning of the bold part! I need to join the "tables" gsm, gpl, gse and gds to filter some metadata.

  Can anyone help me? I would be very greatfull!Thanks in advance  

This isn't a Bioconductor question, but is really a general SQL question. You are asking 'what is an inner join in SQL', which you could use as a Google query to get more information.

The basic idea is that you have two tables in a database, and you want to get data from both tables. The inner join (in SQLite 'join' is the same as 'inner join') is the same as the merge function in R, where you are combining two tables based on columns in each table, and then selecting rows from the resulting table. An inner join forces the constraint that the values being merged on must be found in both tables.