EDIT

BEGIN {

    FS="\t"

    tag_index = 1

}

NR>1{

    print NR"# "$0

    n = split($5, t, ",")

    #print "n: "n

    for (i = 1; i <= n; i++) {

        tag = t[i]

        #print "tag["i"]: "tag

        gsub(/^[ \t]+|[ \t]+$/, "", tag)

        id = get_index(taglist, tag, tagcount)

        if( id < 0){

            # unkown tag, add it to the list

            taglist[tag_index] = tag

            tagcount[tag_index] = 1

            id = tag_index

            tag_index++

        }

        if( tag == "" ) {

                continue

        }

        print "INSERT INTO taggings (tag_id, taggable_id, taggable_type, context, created_at) VALUES("id", "$3", 'Issue', 'tags', NOW());" > "taggings.sql"

    }

}

END {

    for ( k in taglist){

        print "INSERT INTO tags (id, name, taggings_count) VALUES("k", '"taglist[k]"', "tagcount[k]");" > "tags.sql"

    }

}

function get_index(array, value, count_array){

    for ( k in array) {

        if(array[k] == value){

           count_array[k] = count_array[k] + 1

           return k

        } 

    }

    return -1

}

# The following  SQL statement could be used to update the issue journal, but this is not necessary:

# ----

# insert into journal_details (journal_id, property, prop_key, old_value, value) (

#    select jd.journal_id, 'attr', 'tag_list', null, 'swagger, memory'  from journals j join journal_details jd on j.id=jd.journal_id

#        where j.journalized_id = 4414 order by j.created_on DESC LIMIT 1

#    )

# ----