Here is my list (now with this thread added )of this type of questions with all the various answers :)

• Merge two files with similar column entries
• Opening multiple files ( csvpaste.pl )
• Open multiple file handles?
• X, Y Table structure
• How to extract the particular residues from PDB files(text csv split hash bioperl)
• Select only desired features from a text (text csv split hash bioperl)
• Sort on Table headers (text csv split hash bioperl)
• I need help joining tab-delimited files/tables!
• split then join based on common value in field
• Smart way to read a file vertically?