Jarek Jasiewicz wrote:
> D3/3: db_select_int()
> D3/3: SQL: SELECT cat FROM streams_coor WHERE link::text IN(SELECT
> regexp_split_to_table((SELECT branch FROM links WHERE keyid='168'), E'\\.'))
> D3/3: Escaped SQL: SELECT cat FROM streams_coor WHERE link::text
> IN(SELECT regexp_split_to_table((SELECT branch FROM links WHERE
> keyid='168'), E'\\\\.'))
> D3/3: describe_table()
>
> As we see, there is a problem with escape \ backslash
> grass (I don't know gis.m or db_select_int()) adds backslash before.
> In pgAdmin I must add escape character manually as in example in post
> before.
>
> In gis.m this command should look like:
>
> link::text IN(
> SELECT regexp_split_to_table((
> SELECT branch FROM links WHERE keyid='168'), E'\.'))
>
> And everythik is OK. Porblem solved.
db/drivers/postgres/execute.c has the following:
/* Postgres supports in addition to standard escape character '
(apostrophe) also \ (basckslash)
* as this is not SQL standard, GRASS modules cannot work escape all \ in
the text
* because other drivers do not support this feature. For example, if a
text contains
* string \' GRASS modules escape ' by another ' and string passed to
driver is \''
* postgres takes \' as ' but second ' remains not escaped, result is error.
* Because of this, all occurencies of \ in sql are escaped by \ */
str = G_str_replace(db_get_string(sql), "\\", "\\\\");
[Note that "\\" is a string containing a single backslash, as C also
uses backslash as an escape character.]
IOW, the "pg" DBMI driver assumes that every backslash which it sees
is supposed to be a literal backslash, and converts it to a
double-backslash escape sequence to ensure that it is interpreted as
such.
So you can't use PostgreSQL's C-like escapes (\n etc) within SQL
syntax.
--
Glynn Clements <[EMAIL PROTECTED]>
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