How to conduct Row Extraction across different Columns of arrays?

I have a 1x34 array where the columns have different nx7 arrays. In the nx7, column 7 are serial date num. This is a 2 part question.

• 1) How can I create a loop or find and extract the row associated with that date across the 1x34 in chronological order?
• 2) Is there a way as to fill in with empty vectors for dates that are not present?