On Fri, Mar 20, 2015 at 08:43:21AM -0700, David G. Johnston wrote:
> On Thu, Mar 19, 2015 at 6:49 PM, Bruce Momjian <[email protected]> wrote:
> It is making a point about nulls and stuff. There are later queries
> that use format().
>
> I thought maybe you meant those but your specific mention of "
>
> There are other places later in the docs" confused me since you made changes
> before and after that specific section.
>
> Those examples need to be somewhere and it doesn't seem like a undesireable
> enough setup that major reconstructive surgery is warranted to try and move
> them elsewhere.
Yes, agreed.
> I was actually referring to chapter 9
>
> http://www.postgresql.org/docs/9.4/interactive/functions-string.html
>
> The table definitions of the quote_* function should have a comment about
> their equivalency to format %I and %L
I think it is going to be awkward to mention a much more complex
function, format(), when covering a simle quote function.
> Also, in 9.4.1 (format -> type) would be the most obvious place for the
> equivalency of the format %I and %L to quote_*
Yes, added.
Update patch attached and URL udpated with current patch too.
--
Bruce Momjian <[email protected]> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ Everyone has their own god. +
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
new file mode 100644
index aa19e10..3195655
*** a/doc/src/sgml/func.sgml
--- b/doc/src/sgml/func.sgml
***************
*** 2998,3011 ****
<para>
<literal>I</literal> treats the argument value as an SQL
identifier, double-quoting it if necessary.
! It is an error for the value to be null.
</para>
</listitem>
<listitem>
<para>
<literal>L</literal> quotes the argument value as an SQL literal.
A null value is displayed as the string <literal>NULL</>, without
! quotes.
</para>
</listitem>
</itemizedlist>
--- 2998,3012 ----
<para>
<literal>I</literal> treats the argument value as an SQL
identifier, double-quoting it if necessary.
! It is an error for the value to be null (equivalent to
! <function>quote_ident</>).
</para>
</listitem>
<listitem>
<para>
<literal>L</literal> quotes the argument value as an SQL literal.
A null value is displayed as the string <literal>NULL</>, without
! quotes (equivalent to <function>quote_nullable</function>).
</para>
</listitem>
</itemizedlist>
diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
new file mode 100644
index 158d9d2..aee8264
*** a/doc/src/sgml/plpgsql.sgml
--- b/doc/src/sgml/plpgsql.sgml
*************** EXECUTE 'SELECT count(*) FROM '
*** 1222,1227 ****
--- 1222,1234 ----
INTO c
USING checked_user, checked_date;
</programlisting>
+ A cleaner approach is to use <function>format()</>'s <literal>%I</>
+ specification for table or column names:
+ <programlisting>
+ EXECUTE format('SELECT count(*) FROM %I WHERE inserted_by = $1 AND inserted <= $2', tabname)
+ INTO c
+ USING checked_user, checked_date;
+ </programlisting>
Another restriction on parameter symbols is that they only work in
<command>SELECT</>, <command>INSERT</>, <command>UPDATE</>, and
<command>DELETE</> commands. In other statement
*************** EXECUTE 'SELECT count(*) FROM '
*** 1297,1307 ****
</para>
<para>
! Dynamic values that are to be inserted into the constructed
! query require careful handling since they might themselves contain
quote characters.
! An example (this assumes that you are using dollar quoting for the
! function as a whole, so the quote marks need not be doubled):
<programlisting>
EXECUTE 'UPDATE tbl SET '
|| quote_ident(colname)
--- 1304,1317 ----
</para>
<para>
! Dynamic values require careful handling since they might contain
quote characters.
! An example using <function>format()</> (this assumes that you are
! dollar quoting the function body so quote marks need not be doubled):
! <programlisting>
! EXECUTE format('UPDATE tbl SET %I = $1 WHERE key = $2', colname) USING newvalue, keyvalue;
! </programlisting>
! It is also possible to call the quoting functions directly:
<programlisting>
EXECUTE 'UPDATE tbl SET '
|| quote_ident(colname)
*************** EXECUTE 'UPDATE tbl SET '
*** 1393,1407 ****
<programlisting>
EXECUTE format('UPDATE tbl SET %I = %L WHERE key = %L', colname, newvalue, keyvalue);
</programlisting>
The <function>format</function> function can be used in conjunction with
the <literal>USING</literal> clause:
<programlisting>
EXECUTE format('UPDATE tbl SET %I = $1 WHERE key = $2', colname)
USING newvalue, keyvalue;
</programlisting>
! This form is more efficient, because the parameters
! <literal>newvalue</literal> and <literal>keyvalue</literal> are not
! converted to text.
</para>
</example>
--- 1403,1419 ----
<programlisting>
EXECUTE format('UPDATE tbl SET %I = %L WHERE key = %L', colname, newvalue, keyvalue);
</programlisting>
+ <literal>%I</> is equivalent to <function>quote_ident</>, and
+ <literal>%L</> is equivalent to <function>quote_nullable</function>.
The <function>format</function> function can be used in conjunction with
the <literal>USING</literal> clause:
<programlisting>
EXECUTE format('UPDATE tbl SET %I = $1 WHERE key = $2', colname)
USING newvalue, keyvalue;
</programlisting>
! This form is better because the variables are handled in their native
! data type format, rather than unconditionally converting them to
! text and quoting them via <literal>%L</>. It is also more efficient.
</para>
</example>
*************** BEGIN
*** 2352,2361 ****
-- Now "mviews" has one record from cs_materialized_views
RAISE NOTICE 'Refreshing materialized view %s ...', quote_ident(mviews.mv_name);
! EXECUTE 'TRUNCATE TABLE ' || quote_ident(mviews.mv_name);
! EXECUTE 'INSERT INTO '
! || quote_ident(mviews.mv_name) || ' '
! || mviews.mv_query;
END LOOP;
RAISE NOTICE 'Done refreshing materialized views.';
--- 2364,2371 ----
-- Now "mviews" has one record from cs_materialized_views
RAISE NOTICE 'Refreshing materialized view %s ...', quote_ident(mviews.mv_name);
! EXECUTE format('TRUNCATE TABLE %I', mviews.mv_name);
! EXECUTE format('INSERT INTO %I %s', mviews.mv_name, mviews.mv_query);
END LOOP;
RAISE NOTICE 'Done refreshing materialized views.';
*************** OPEN <replaceable>unbound_cursorvar</rep
*** 2968,2974 ****
from one run to the next (see <xref linkend="plpgsql-plan-caching">),
and it also means that variable substitution is not done on the
command string. As with <command>EXECUTE</command>, parameter values
! can be inserted into the dynamic command via <literal>USING</>.
The <literal>SCROLL</> and
<literal>NO SCROLL</> options have the same meanings as for a bound
cursor.
--- 2978,2985 ----
from one run to the next (see <xref linkend="plpgsql-plan-caching">),
and it also means that variable substitution is not done on the
command string. As with <command>EXECUTE</command>, parameter values
! can be inserted into the dynamic command via
! <literal>format()</> and <literal>USING</>.
The <literal>SCROLL</> and
<literal>NO SCROLL</> options have the same meanings as for a bound
cursor.
*************** OPEN <replaceable>unbound_cursorvar</rep
*** 2977,2989 ****
<para>
An example:
<programlisting>
! OPEN curs1 FOR EXECUTE 'SELECT * FROM ' || quote_ident(tabname)
! || ' WHERE col1 = $1' USING keyvalue;
</programlisting>
! In this example, the table name is inserted into the query textually,
! so use of <function>quote_ident()</> is recommended to guard against
! SQL injection. The comparison value for <literal>col1</> is inserted
! via a <literal>USING</> parameter, so it needs no quoting.
</para>
</sect3>
--- 2988,2999 ----
<para>
An example:
<programlisting>
! OPEN curs1 FOR EXECUTE format('SELECT * FROM %I WHERE col1 = $1',tabname) USING keyvalue;
</programlisting>
! In this example, the table name is inserted into the query via
! <function>format()</>. The comparison value for <literal>col1</>
! is inserted via a <literal>USING</> parameter, so it needs
! no quoting.
</para>
</sect3>
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