primary key – Understanding linking tables in a many-to-many relationship

I am still working on a photo storage app (designing the database for the data for the photos stored), using MySQL, and have been told that a photo may have one or more people in it, and a person may be in many photographs, which makes sense.

My issue is in understanding the properties of the linking table between the photo and person tables. I have set up a linking table with the PK of both tables (Photo and Person) as the composite PK for the linking table. Both sets of PK in this table are set to Not Null (by me) but the project then stipulates that people can be in the database even if they aren’t in a photo, and I was wondering how this tallies with the NN setting of the composite PK. Surely if it has to be NN, this means it can’t allow for there to be any entries where I just have the PK of the photo and none for the person part of the linking table? Or am I totally misunderstanding how these relationships work? As mentioned previously, I am in the early stages of learning about databases.

search engine indexing – Will App Universal linking improve domain ranking?

I build a mobile app. It’ll have “share” button, which will be sharing link like

The itself is a one-page landing.

  1. If users will share the deep links on the internet, will it improve search ranking of the landing page?
  2. Would it be better to use root url like instead of

Why are unknown sites to which I don’t link listed in Google Search Console’s “Top linking sites” report?

Those are sites that link to your site, not sites to which you link. If you click on the circled question mark, you can see Google’s explanation:

Links from outside your property to your property. Values are trimmed to root domain and grouped. If the current property is listed here, it is because the subdomain of the host page has been omitted. For example, if the link is from, the value shown here would be

You can see exactly which pages link to your site and which pages they link to.

  1. Clicking on the site. It will take you to the “Top target pages” where you can see which pages on your site get the link.
  2. Click on the page from your site. It will take you to the “Top linking pages” report which shows you which pages on the external site link to your page.

disavow links – One domain linking single post over 1,000 time looks spamming?

When I’m checking Google webmaster tool, it shows one domain linking 1,067 times to my blog single post. All these 1,067 are different blog posts in that site. That site owner added my one blog post as a troubleshooting guide with a Click anchor text.

I didn’t create these backlinks and I have no connection with him/her. I would like to know that, is it spamming backlink? Should I “Disavow” this domain from Google webmaster tool?

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links – Repeated Anchor Text while internal linking for SEO

Having many interal links to any single page that has the same anchor text is fine. On this site, almost every link to a question will have anchor text of the title of the question. Repeated anchor text just indicates that the site is powered by a database. There is no penalty for having a database driven site. It is a very common case.

There are some cases where anchor text can get you into trouble internally. Repeating the same words in a list of links is really bad SEO these days. Consider the following list of links:

  • Lounge Bars Dubai
  • Lounge Bars Paris
  • Lounge Bars Copenhagen
  • Lounge Bars New York
  • Lounge Bars Taiwan

That looks really spammy. Users are not going to appreciate that. Something like this looks much better:

Lounge bars in other cities

  • Dubai
  • Paris
  • Copenhagen
  • New York
  • Taiwan

A few years ago, internal anchor text was very important. It was best when it matched the pages that it was pointing to. To rank well you had to use “Lounge Bars Dubai” as your anchor text on links to those pages.

That is no longer the case. Internal anchor text doesn’t count for much of anything these days as far as I can tell. Only anchor text from external links seems to have any keyword weight.

In fact, Google has started to penalize spammy repetition more. You are much more likely to penalized for keyword stuffing than get a boost for exact match anchor text if your list of links looks like the first one.

I would also recommend putting no more than 10 items in any list of links. Users almost never use more links than that in a list. Long lists of links are another sign of spam.

Linking Some Tables

I have three tables :

Product ID key

Order Item
Order ID key
Product ID fkey

Saved Orders (a record of bought transactions)
SavedOrderID key
Product ID fkey

The order item reduces its quantity when an order is made. If all of the item is bought than the order item record is deleted.

My question are:

1. Does the link and columns look okay for the three tables?
2. Should Saved Orders be a separate database?
3. If there is some database where a table such as Customers can link to more than one column what is done?

Thanks a ton,


usability – Technical terms linking vertical lists to Instructions

I once read a study where it described that displaying information vertically hints/implies to the user that it is instructions. I tried searching for proof of this concept again and couldn’t find it this time.

Does anyone know any key terms/concepts relating to information being displayed vertically rather than horizontally means its implying that the information is instructions/guidelines to follow.

Heres an example of what I mean.

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privacy – Linking addresses to wallets

Chain analysis companies use many heuristics to link addresses into wallets.
The most popular being:

  • common input heuristic where all addresses are grouped by the premise of being inputs to the same transaction
  • change analysis heuristic which looks at the transaction outputs trying to group them by recipient and change address
  • other methods, like grouping through SPV vulnerabilities, time analysis, pattern analysis

But the easier way of getting the identity of the address is (for the law enforcement) to subpeana exchange, which will link your identity to any address you used to interact with this exchange. You can’t just convert bitcoin to Monero without using service like exchange, or if you are really lucky you may try doing it P2P but this pose another set of risks.
But if you are looking into privacy features, I’d point you to implementations of coinjoin (Samourai, Wasabi, Joinmarket) which may help with breaking said heuristics.


What is the best and fastest method of linking? – SEO help (general chat)

Hey friend,
The fastest link building has been harmful for a few days. If you want to get a ranking, you need to create quality backlinks, not the quantity of it. A good backlink is better than many worse backlinks.

Generally, the infographics are up there.
People love these things and you host them and provide the embed code to other sites so that they are all linked to you.