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Improve documentation for \crosstabview.

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Fix misleading syntax summary (there cannot be a space between colH and
scolH).  Provide a link from the existing crosstab() function's
documentation to \crosstabview.  Copy-edit the command's description.

Christoph Berg and Tom Lane
This commit is contained in:
Tom Lane
2016-04-13 11:49:47 -04:00
parent cbb2a812d7
commit 85e0047077
2 changed files with 51 additions and 71 deletions
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114
doc/src/sgml/ref/psql-ref.sgml
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@ -989,106 +989,78 @@ testdb=>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry>
<varlistentry id="APP-PSQL-meta-commands-crosstabview">
<term><literal>\crosstabview [ <term><literal>\crosstabview [
<replaceable class="parameter">colV</replaceable> <replaceable class="parameter">colV</replaceable>
<replaceable class="parameter">colH</replaceable> <replaceable class="parameter">colH</replaceable>[:<replaceable class="parameter">scolH</replaceable>]
[:<replaceable class="parameter">scolH</replaceable>]
[<replaceable class="parameter">colD</replaceable>] [<replaceable class="parameter">colD</replaceable>]
] </literal></term> ] </literal></term>
<listitem> <listitem>
<para> <para>
Execute the current query buffer (like <literal>\g</literal>) and shows Executes the current query buffer (like <literal>\g</literal>) and
the results inside a crosstab grid. shows the results in a crosstab grid.
The query must return at least three columns. The query must return at least three columns.
The output column <replaceable class="parameter">colV</replaceable> The output column identified by <replaceable class="parameter">colV</>
becomes a vertical header becomes a vertical header and the output column identified by
and the output column <replaceable class="parameter">colH</replaceable> <replaceable class="parameter">colH</replaceable>
becomes a horizontal header, optionally sorted by ranking data obtained becomes a horizontal header, optionally sorted by ranking data obtained
from <replaceable class="parameter">scolH</replaceable>. from column <replaceable class="parameter">scolH</replaceable>.
<replaceable class="parameter">colD</replaceable> <replaceable class="parameter">colD</replaceable> identifies
is the output column to project into the grid. If this is not the output column to display within the grid.
If <replaceable class="parameter">colD</replaceable> is not
specified and there are exactly three columns in the result set, specified and there are exactly three columns in the result set,
the column that isn't the column that is neither
<replaceable class="parameter">colV</replaceable> nor <replaceable class="parameter">colV</replaceable> nor
<replaceable class="parameter">colH</replaceable> <replaceable class="parameter">colH</replaceable>
is displayed; if there are more columns, an error is thrown. is displayed; if there are more columns, an error is reported.
</para> </para>
<para> <para>
All columns can be refered to by their position (starting at 1), or by Each column specification can be a column number (starting at 1) or
their name. Normal case folding and quoting rules apply on column a column name. The usual SQL case folding and quoting rules apply to
names. By default, column names. If omitted,
<replaceable class="parameter">colV</replaceable> corresponds to column 1 <replaceable class="parameter">colV</replaceable> is taken as column 1
and <replaceable class="parameter">colH</replaceable> to column 2. and <replaceable class="parameter">colH</replaceable> as column 2.
A query having only one output column cannot be viewed in crosstab, and
<replaceable class="parameter">colH</replaceable> must differ from <replaceable class="parameter">colH</replaceable> must differ from
<replaceable class="parameter">colV</replaceable>. <replaceable class="parameter">colV</replaceable>.
</para> </para>
<para> <para>
The vertical header, displayed as the leftmost column, The vertical header, displayed as the leftmost column, contains the
contains the deduplicated values found in values found in column <replaceable class="parameter">colV</>, in the
column <replaceable class="parameter">colV</replaceable>, in the same same order as in the query results, but with duplicates removed.
order as in the query results.
</para> </para>
<para> <para>
The horizontal header, displayed as the first row, The horizontal header, displayed as the first row, contains the values
contains the deduplicated values found in found in column <replaceable class="parameter">colH</replaceable>,
column <replaceable class="parameter">colH</replaceable>, in with duplicates removed. By default, these appear in the same order
the order of appearance in the query results. as in the query results. But if the
If specified, the optional <replaceable class="parameter">scolH</replaceable> optional <replaceable class="parameter">scolH</> argument is given, it
argument refers to a column whose values should be integer numbers identifies a column whose values must be integer numbers, and the
by which <replaceable class="parameter">colH</replaceable> will be sorted values from <replaceable class="parameter">colH</replaceable> will
to be positioned in the horizontal header. appear in the horizontal header sorted according to the
corresponding <replaceable class="parameter">scolH</> values.
</para> </para>
<para> <para>
Inside the crosstab grid, Inside the crosstab grid, for each distinct value <literal>x</literal>
given a query output with <literal>N</literal> columns of <replaceable class="parameter">colH</replaceable> and each distinct
(including <replaceable class="parameter">colV</replaceable> and value <literal>y</literal>
<replaceable class="parameter">colH</replaceable>), of <replaceable class="parameter">colV</replaceable>, the cell located
for each distinct value <literal>x</literal> of at the intersection <literal>(x,y)</literal> contains the value of
<replaceable class="parameter">colH</replaceable> the <literal>colD</literal> column in the query result row for which
and each distinct value <literal>y</literal> of the value of <replaceable class="parameter">colH</replaceable>
<replaceable class="parameter">colV</replaceable>, is <literal>x</literal> and the value
the contents of a cell located at the intersection of <replaceable class="parameter">colV</replaceable>
<literal>(x,y)</literal> is determined by these rules: is <literal>y</>. If there is no such row, the cell is empty. If
<itemizedlist> there are multiple such rows, an error is reported.
<listitem>
<para>
if there is no corresponding row in the query results such that the
value for <replaceable class="parameter">colH</replaceable>
is <literal>x</literal> and the value
for <replaceable class="parameter">colV</replaceable>
is <literal>y</literal>, the cell is empty.
</para> </para>
</listitem> </listitem>
<listitem>
<para>
if there is exactly one row such that the value
for <replaceable class="parameter">colH</replaceable>
is <literal>x</literal> and the value
for <replaceable class="parameter">colV</replaceable>
is <literal>y</literal>, then the <literal>colD</literal> column
is displayed.
</para>
</listitem>
<listitem>
<para>
if there are several such rows, an error is thrown.
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><literal>\d[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term> <term><literal>\d[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>

8
doc/src/sgml/tablefunc.sgml
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@ -293,6 +293,14 @@ AS ct(row_name text, category_1 text, category_2 text, category_3 text);
required <literal>FROM</> clause in a view definition. required <literal>FROM</> clause in a view definition.
</para> </para>
<note>
<para>
See also the <command><link linkend="APP-PSQL-meta-commands-crosstabview">\crosstabview</link></command>
command in <application>psql</>, which provides functionality similar
to <function>crosstab()</>.
</para>
</note>
</sect3> </sect3>
<sect3> <sect3>