Script checking to see what database it's connected to

>
> Postgresql 12.5
>
> I've got scripts which can run on multiple database (dev, test, QA,
> Integration, Training, etc, etc), so of course I've got to run them like
> "psql my_db_name -f script.sql".
>
> Of course, I sometimes forget to specify the database name, and so it
> fails.
>
> Thus, I want to add a bit to the top of the script, something like this:
>
> \if :DBNAME = postgres
>      echo "must not run in postgres"
>      exit
> \endif
>
> However, I can't seem to find the magic sauce.
>
> This is what I've tried so far:
>
> postgres=# \if :DBNAME == postgres
> unrecognized value "postgres == postgres" for "\if expression": Boolean
> expected
> postgres@#
>
> postgres=# \if ':DBNAME' == postgres
> unrecognized value ":DBNAME == postgres" for "\if expression": Boolean
> expected
> postgres@#
>
> postgres=# \if :DBNAME == 'postgres'
> unrecognized value "postgres == postgres" for "\if expression": Boolean
> expected
> postgres@#
>
> postgres=# \if ':DBNAME' == 'postgres'
> unrecognized value ":DBNAME == postgres" for "\if expression": Boolean
> expected
> postgres@#
>
>

>
>
> On 2/21/21 4:18 PM, Ron wrote:
>>
>> Postgresql 12.5
>>
>> I've got scripts which can run on multiple database (dev, test, QA,
>> Integration, Training, etc, etc), so of course I've got to run them like
>> "psql my_db_name -f script.sql".
>>
>> Of course, I sometimes forget to specify the database name, and so it fails.
>>
>> Thus, I want to add a bit to the top of the script, something like this:
>>
>> \if :DBNAME = postgres
>>      echo "must not run in postgres"
>>      exit
>> \endif
>>
>> However, I can't seem to find the magic sauce.
>>
>> This is what I've tried so far:
>>
>> postgres=# \if :DBNAME == postgres
>> unrecognized value "postgres == postgres" for "\if expression": Boolean
>> expected
>> postgres@#
>>
>> postgres=# \if ':DBNAME' == postgres
>> unrecognized value ":DBNAME == postgres" for "\if expression": Boolean
>> expected
>> postgres@#
>>
>> postgres=# \if :DBNAME == 'postgres'
>> unrecognized value "postgres == postgres" for "\if expression": Boolean
>> expected
>> postgres@#
>>
>> postgres=# \if ':DBNAME' == 'postgres'
>> unrecognized value ":DBNAME == postgres" for "\if expression": Boolean
>> expected
>> postgres@#
>>
>>
>
> Take it up a notch?  Write a script which takes the dbname and the script
> name:
>
> /pcode/
>
> #!/bin/bash -e
> if [[ $# -ne 2 ]]; then echo "missing arg(s)"; exit 2; fi
> dbn=$1; shift;
> sql=$1; shift;
> psql --dbname $dbn --file $sql
>
> /pcode/

>>
>> Take it up a notch?  Write a script which takes the dbname and the
>> script name:
>>
>> /pcode/
>>
>> #!/bin/bash -e
>> if [[ $# -ne 2 ]]; then echo "missing arg(s)"; exit 2; fi
>> dbn=$1; shift;
>> sql=$1; shift;
>> psql --dbname $dbn --file $sql
>>
>> /pcode/
>
> I thought of that, yet so earnestly want avoid Yet Another Tiny Script.
>

>>>
>>> Take it up a notch?  Write a script which takes the dbname and the
>>> script name:
>>>
>>> /pcode/
>>>
>>> #!/bin/bash -e
>>> if [[ $# -ne 2 ]]; then echo "missing arg(s)"; exit 2; fi
>>> dbn=$1; shift;
>>> sql=$1; shift;
>>> psql --dbname $dbn --file $sql
>>>
>>> /pcode/
>>
>> I thought of that, yet so earnestly want avoid Yet Another Tiny Script.
>>
> Isn't it a toss-up with putting the check in every sql script?
> Or make it /really/ fancy: use proper arg parsing; check for existence
> of the sql script;  add a usage function; split stdout/stderr...  No end
> of fun.

>
>
>>>
>>> Take it up a notch?  Write a script which takes the dbname and the
>>> script name:
>>>
>>> /pcode/
>>>
>>> #!/bin/bash -e
>>> if [[ $# -ne 2 ]]; then echo "missing arg(s)"; exit 2; fi
>>> dbn=$1; shift;
>>> sql=$1; shift;
>>> psql --dbname $dbn --file $sql
>>>
>>> /pcode/
>>
>> I thought of that, yet so earnestly want avoid Yet Another Tiny Script.
>>
> Isn't it a toss-up with putting the check in every sql script?

>
> On 2/21/21 5:26 PM, Julien Rouhaud wrote:
>
> On Mon, Feb 22, 2021 at 7:19 AM Ron <[hidden email]> wrote:
>
> Thus, I want to add a bit to the top of the script, something like this:
>
> \if :DBNAME = postgres
>      echo "must not run in postgres"
>      exit
> \endif
>
> However, I can't seem to find the magic sauce.
>
> You have to use a dedicated variable.  Something like
>
> SELECT :'DBNAME' = 'postgres' AS is_postgres \gset
>
>
> That works...
>
> \if :is_postgres
> [...]
>
>
> That almost works,
>
> My script:
> $ cat test_pg.sql
> SELECT :'DBNAME' = 'postgres' AS is_postgres \gset
> \echo :is_postgres
> \if :is_postgres
>     \echo 'connected to postgres'
>     exit
> \else
>     \echo 'not connected to postgres'
> \endif
>
> The output:
> $ psql12 -f test_pg.sql
> t
> connected to postgres
> got here
> psql:test_pg.sql:15: ERROR:  syntax error at or near "exit"
> LINE 1: exit

>> The output:
>> $ psql12 -f test_pg.sql
>> t
>> connected to postgres
>> got here
>> psql:test_pg.sql:15: ERROR:  syntax error at or near "exit"
>> LINE 1: exit
>
> Well, the supported commands did work.  You should probably look at
> https://www.postgresql.org/docs/current/app-psql.html, you'd see that
> "exit" is not a supported command and you should instead use \q[uit].
> I recommend looking at the semantics of \quit though, given your next
> message mentioning \include.