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Comment by AtNightWeCode | Hacker News Reader

Never use WHERE 1=1. It is both a security risk and a performance risk to run dynamic ad-hoc queries.

Can you expand on this? How is having

    WHERE 1=1
    AND ...[usual-where-clause]...

A performance and security compared to doing

    WHERE ...[usual-where-clause]...

If you use it in the same way you use trailing commas. Fair. But the site says to make it easier to add dynamic conditions. Which is a terrible idea in maybe not all but many SQL engines.

What is a dynamic, adhoc query? Why does adding 1=1 support that?

I'm wondering that as well. I don't get that suggestion at all.

Lets say its 2001 and you are writing some hot e-commerce stuff in plain php. You want to filter data depending on multiple fields in the submitted form. If some field is there, you add one more "AND" clause to the "WHERE", like this: if (isset($_POST['product'])) { $query .= "AND product = " . $_POST['product']; }. So in order not to check every time if the added clause is the first one you start with "WHERE 1=1 ", as "WHERE AND ..." would not work.

Php has nothing like this?

In [1]: "... WHERE " + " AND ".join(str(i) for i in range(4))

Out[1]: '... WHERE 0 AND 1 AND 2 AND 3'

Very strange.

This will produce broken SQL on empty clauses list. Very strange.

You're quite right, but this is easily fixed. That doesn't change my question, since something like this is much easier that the other logic.

The easiest fix for this is the "WHERE 1=1" or "WHERE true"

I get how this isn't good. But how else would you handle multi-field filtering, keep all the ANDs and use (product_id = $1 OR $1 IS NULL) so the unset filters are no-op? That's ok as long as the query planner is smart enough.

In this case. A query that you build by adding different strings. 1=1 is for adding AND statements to the WHERE clause dynamically. In your code. I never seen it used for anything else. Adhoc is just the practice of running raw SQL queries.

So you end up with things like this.

"SELECT * FROM Music WHERE 1=1" + "AND category='rock'"

The risk is now that you by mistake allow for SQL-injections but also every genre will generate a different query plan. Depending on what SQL engine you use this may hurt performance.

And one would think that this is a thing of the past. But it is not.

Can you elaborate on security issues here?

I think that it means the reason for doing where 1 = 1 is sometimes to allow for easy insertion of dynamic queries which can be a security and performance issue. The actual usage of where 1 = 1 doesn't cause the security or performance issue.

Which is exactly what the site says. To insert dynamic conditions. I know that you can use 1=1 for the same reasons as trailing commas. But kinda obvious that this is not the case here.

Just to be clear I'm using it for the same reason as trailing commas.

If I'm inspecting a dataset I use WHERE 1=1 so I can add and remove conditions more easily.

I realise the confusion is in my wording of dynamic - I might amend the README.md to clarify. Thanks for the feedback!

Presumably you are thinking about queries in code that add WHERE clauses dynamically that aren't escaped correctly- which doesn't have to be the case.

1 = 1 is at least handy for simply joining a variadic amount of other clauses with ' AND ' rather than counting if there's any to add at all.

Yes. "Use a dummy value in the WHERE clause so you can dynamically add and remove conditions with ease:" I don't know how to read this in another way.

I've amended the README.md to explain what I meant. My error was in using the word dynamic!

I'll add this as a caveat. I'm an analyst so my SQL isn't really exposed to anyone other than myself and so I wasn't aware of this, thanks for flagging.

A random person claims adding 1=1 is a security risk and you are going to add it as caveat without verifying if the claim is true nor knowing why? That's how misinformation spreads around.

OP doesn't know what they are talking about because adding 1=1 is not a security risk. 1=1 is related to sql injections where a malicious attacker injects 'OR 1=1' into the end of the where clause to disable the where clause completely. OP probably saw '1=1' and threw that into the comment.

Fair point!

Read my other comments. I worked with SQL on and off since the last century. It has nothing to do with your poor assumptions.

Duration of working with SQL doesn't matter. The better SQL programmers don't do it specifically, and have experience in real languages that they bring over to database queries.

Not sure I get this. But I think it does matter since you understand why people do it to begin with. I worked on two enterprise solutions over the last couple of years that have this exact problem. That people are using WHERE 1=1 and then add random "AND something=something" that completely trashes the performance of the db. Also, it does not matter as much on-prem. But in cloud envs it does. Since you can't really spike CPU and mem the same way as on-prem.

The reason I pointed out this specific issue is just that I thought it was the worsed of many poor tips. ChatGPT can give better tips.

If the query planner can't optimize out "IF TRUE" I don't know what to say. Is there something deeper happening or is this just gross incompetence?

Jesus. The problem is not WHERE 1=1. It is WHY people do it. People do it because they then in Python, JS or whatever can easily add conditions. Like QUERY + "AND x='blabla'". There is the problem. Every time you create a unique SQL statement the query will need a new query plan in most SQL engines. Some will cache parts of the query. And you could use parameters along with this paradigm but if you are this bad at SQL I doubt it.

It is kinda funny that op backpedal on this cause to me the whole site is amateurish. I just pointed out what I thought was the worst part. It is likely that it is generated by AI. Either way the post is terrible.

I'm an analyst so I literally only query for analytical purposes. I don't have any SQL code embedded in an application so the 1=1 is purely for tweaking/testing a query more quickly.

I certainly didn't use AI, all these tips/tricks are from work experience and reading Snowflake documentation and the like, but I guess I can't convince you either way. Regardless I appreciate the feedback!

1=1 is not a security risk

This doesn't make any sense at all.

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