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<chapter id="functions">

<title>Functions and Operators</title>

</row>

<row>

<entry><literal>D</literal></entry>

<entry>day of week (1-7; Sunday is 1)</entry>

<entry>day oftheweek, Sunday(<literal>1</>) to Saturday(<literal>7</>)</entry>

</row>

<row>

<entry><literal>ID</literal></entry>

<entry>ISO day of week (1-7; Monday is 1)</entry>

<entry>ISO day oftheweek, Monday(<literal>1</>) to Sunday(<literal>7</>)</entry>

</row>

<row>

<entry><literal>W</literal></entry>

</listitem>

<listitem>

<para><function>to_char</function>'s day of the week numbering

(see the 'D' formatting pattern) is different from that of the

<function>extract</function> function.

<para>

<function>to_char(..., 'ID')</function>'s day of the week numbering

matches the <function>extract('isodow', ...)</function> function.

<function>to_char(..., 'D')</function>'s does not match

<function>extract('dow', ...)</function>'s day numbering.

</para>

</listitem>

<lineannotation>Result: </lineannotation><computeroutput>5</computeroutput>

</screen>

<para>

Note that <function>extract</function>'s day of the week numbering is

different from that of the <function>to_char</function> function.

Note that <function>extract</function>'s day of the week numbering

is different from that of the <function>to_char(...,

'D')</function> function.

</para>

</listitem>