@ET I am assuming you are posting only a part of your query, you can't start a SQL query with

EXISTS

, you presumably want to have some form of a

SELECT

statement. Furthermore, your

EXISTS

pattern does not make sense as written. If I wrote:

SELECT 'test' AS foo WHERE EXISTS(SELECT size from file WHERE path = '/tmp/et.txt');

The logic executed would be the following. Select a given string (

'test' AS foo

), if a path matching:

'/tmp/et.txt'

exists in the

file

table. Because

size

is not constrained in the

WHERE

clause it has no bearing on the output of the query. Likewise it will never be _SELECT_ed because you are using an

EXISTS

condition which operates like a boolean. If you wanted to sub-select

size

for your '/tmp/et.txt' file you would need to modify your query. Using EXISTS here is duplicative and the same goal could be accomplished without it by doing the following:

SELECT 'test' AS foo WHERE (SELECT 1 FROM file WHERE path = '/tmp/et.txt');

--- I assume you are trying to do something else here but it is hard to guess based on the snippet alone. If you tell me the exact use-case you are trying to solve for, I would be more than happy to help you craft the SQL.

Thanks @fritz I want to get a boolean response to the question if the file exists or not

@ET 👍

10x! 🙂

In general, I tend not to use

EXISTS

as it's rarely needed instead of a simple

WHERE(SUB QUERY)

NOT EXISTS

on the other hand is often useful to me. For example, let's say I wanted to get all the

system_info

for a device that wasn't running the 'foobarbaz' process:

SELECT * FROM system_info WHERE NOT EXISTS (SELECT 1 FROM processes WHERE name = 'foobarbaz');

---

hostname = fritz-imac.lan
              uuid = E664D52B-5FBC-....
          cpu_type = x86_64h
       cpu_subtype = Intel x86-64h Haswell
         cpu_brand = Intel(R) Xeon(R) W-2140B CPU @ 3.20GHz
cpu_physical_cores = 8
 cpu_logical_cores = 16
     cpu_microcode = 
   physical_memory = 34359738368
   hardware_vendor = Apple Inc.
    hardware_model = iMacPro1,1
  hardware_version = 1.0
...