Обсуждение: Single quotes vs. double quotes when setting a pwd and other cmds

Hello,

why aren't double quotes accepted below?

db1=# alter user user1 password "pass1";
ERROR:  syntax error at or near ""pass1""
LINE 1: alter user user1 password "pass1";
                                 ^
db1=# alter user user1 password 'pass1';
ALTER ROLE

Is there a thumb rule to know when to use which quotes?
I'm often confused by them when using psql.

Thank you
Alex

PS: Using postgresql-server-8.3.6 @ OpenBSD 4.5

Le 23/06/2010 11:03, Alexander Farber a écrit :
> Hello,
>
> why aren't double quotes accepted below?
>
> db1=# alter user user1 password "pass1";
> ERROR:  syntax error at or near ""pass1""
> LINE 1: alter user user1 password "pass1";
>                                  ^
> db1=# alter user user1 password 'pass1';
> ALTER ROLE
>
> Is there a thumb rule to know when to use which quotes?
> I'm often confused by them when using psql.
>

Use double quotes for identifiers, and single quotes for string values.

The password is a string, so you use single quotes with it. The username
is an identifier, so you (can) use double quotes with it.


--
Guillaume
 http://www.postgresql.fr
 http://dalibo.com

Hello

ANSI SQL uses double quotes only for SQL identifiers. For literals are
used single quotes.

like

SELECT col AS "some strange sql column identifier", 'some string
value' FROM "some strange sql table identifier"

so for case sensitive or strange (is keyword, contains space) sql
identifiers use double quotes, for string constants use single quotes.

some other database uses [] or ` .

Regards
Pavel


2010/6/23 Alexander Farber <alexander.farber@gmail.com>:
> Hello,
>
> why aren't double quotes accepted below?
>
> db1=# alter user user1 password "pass1";
> ERROR:  syntax error at or near ""pass1""
> LINE 1: alter user user1 password "pass1";
>                                 ^
> db1=# alter user user1 password 'pass1';
> ALTER ROLE
>
> Is there a thumb rule to know when to use which quotes?
> I'm often confused by them when using psql.
>
> Thank you
> Alex
>
> PS: Using postgresql-server-8.3.6 @ OpenBSD 4.5
>
> --
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>

In response to Alexander Farber :
> Hello,
>
> why aren't double quotes accepted below?
>
> db1=# alter user user1 password "pass1";
> ERROR:  syntax error at or near ""pass1""
> LINE 1: alter user user1 password "pass1";
>                                  ^
> db1=# alter user user1 password 'pass1';
> ALTER ROLE
>
> Is there a thumb rule to know when to use which quotes?
> I'm often confused by them when using psql.

Use ' for variable strings (values), and " for identifier (table-name,
column-name).


Andreas
--
Andreas Kretschmer
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GnuPG: 0x31720C99, 1006 CCB4 A326 1D42 6431  2EB0 389D 1DC2 3172 0C99

And identifiers means column names (eventually containing whitespace)?

Thank you
Alex

In response to Alexander Farber :
> And identifiers means column names (eventually containing whitespace)?

Right.

test=# select 'foo' as "my new column";
 my new column
---------------
 foo
(1 row)

Regards, Andreas
--
Andreas Kretschmer
Kontakt:  Heynitz: 035242/47150,   D1: 0160/7141639 (mehr: -> Header)
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On 23 June 2010 10:41, Alexander Farber <alexander.farber@gmail.com> wrote:
> And identifiers means column names (eventually containing whitespace)?
>

Columns, tables, schemas, views, triggers, indexes etc.  See:
http://www.postgresql.org/docs/8.4/static/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS

Regards

Thom

A. Kretschmer wrote:
> In response to Alexander Farber :
> > And identifiers means column names (eventually containing whitespace)?
>
> Right.
>
> test=# select 'foo' as "my new column";
>  my new column
> ---------------
>  foo
> (1 row)

And double-quotes preserve case:

    test=> select 'foo' as Mine;
     mine
    ------
     foo
    (1 row)

    test=> select 'foo' as "Mine";   <-- double-quotes
     Mine  <--
    ------
     foo
    (1 row)

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  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + None of us is going to be here forever. +