SRA- GALAXY read input

[Babhitha_Balaji]

Hello everyone I have a doubt, why do I have to input two FASTQ files from NCBI when I only have to align one read against the reference genome?

[gbbio]

Which tool do you want to use to align? And do you already have a FASTQ file? Is it possible that your single fastq dataset is representing a paired-end run? If that is the case you can look at the tool named FASTQ splitter.

Maybe this page can also help:

Galaxy Training: NCBI SRA sourced fastq data

[Babhitha_Balaji]

After this step of uploading one SRA file in GALAXY

Why do we have to select two SRA accessions in the patterns field?

[gbbio]

Because it is just a tutorial and if you process all accessions it would take a while. It is explained on the page (under your first screenshot).
Hope this answers your question.
See selected in red: