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@ -1,5 +1,5 @@ |
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<!-- |
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<!-- |
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$Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.172 2003/09/11 18:30:38 momjian Exp $ |
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$Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.173 2003/09/12 22:17:22 tgl Exp $ |
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PostgreSQL documentation |
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PostgreSQL documentation |
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--> |
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--> |
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@ -3890,8 +3890,8 @@ substring('foobar' from 'o(.)b') <lineannotation>o</lineannotation> |
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</table> |
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</table> |
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<para> |
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<para> |
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Warning. <literal><function>to_char</function>(<type>interval</type>, <type>text</type>)</literal> |
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Warning: <literal><function>to_char</function>(<type>interval</type>, <type>text</type>)</literal> |
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is deprecated and should not be used in newly-written code. Will be removed in the next version. |
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is deprecated and should not be used in newly-written code. It will be removed in the next version. |
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</para> |
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</para> |
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<para> |
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<para> |
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@ -6403,6 +6403,15 @@ SELECT a, |
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3 | other |
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3 | other |
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</screen> |
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</screen> |
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</para> |
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</para> |
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<para> |
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A <token>CASE</token> expression does not evaluate any subexpressions |
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that are not needed to determine the result. For example, this is a |
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possible way of avoiding a division-by-zero failure: |
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<programlisting> |
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SELECT ... WHERE CASE WHEN x <> 0 THEN y/x > 1.5 ELSE false END; |
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</programlisting> |
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</para> |
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</sect2> |
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</sect2> |
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<sect2> |
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<sect2> |
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@ -6418,13 +6427,21 @@ SELECT a, |
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<para> |
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<para> |
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The <function>COALESCE</function> function returns the first of its |
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The <function>COALESCE</function> function returns the first of its |
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arguments that is not null. This is often useful to substitute a |
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arguments that is not null. Null is returned only if all arguments |
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are null. This is often useful to substitute a |
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default value for null values when data is retrieved for display, |
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default value for null values when data is retrieved for display, |
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for example: |
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for example: |
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<programlisting> |
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<programlisting> |
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SELECT COALESCE(description, short_description, '(none)') ... |
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SELECT COALESCE(description, short_description, '(none)') ... |
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</programlisting> |
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</programlisting> |
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</para> |
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</para> |
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<para> |
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Like a <token>CASE</token> expression, <function>COALESCE</function> will |
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not evaluate arguments that are not needed to determine the result; |
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that is, arguments to the right of the first non-null argument are |
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not evaluated. |
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</para> |
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</sect2> |
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</sect2> |
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<sect2> |
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<sect2> |
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@ -7277,6 +7294,21 @@ SELECT pg_type_is_visible('myschema.widget'::regtype); |
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<tbody> |
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<tbody> |
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<row> |
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<row> |
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<entry> |
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<entry> |
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<literal> |
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<function>array_cat</function> |
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(<type>anyarray</type>, <type>anyarray</type>) |
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</literal> |
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</entry> |
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<entry><type>anyarray</type></entry> |
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<entry> |
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concatenate two arrays, returning <literal>NULL</literal> |
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for <literal>NULL</literal> inputs |
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</entry> |
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<entry><literal>array_cat(ARRAY[1,2,3], ARRAY[4,5])</literal></entry> |
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<entry><literal>{1,2,3,4,5}</literal></entry> |
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</row> |
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<row> |
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<entry> |
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<literal> |
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<literal> |
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<function>array_append</function> |
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<function>array_append</function> |
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(<type>anyarray</type>, <type>anyelement</type>) |
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(<type>anyarray</type>, <type>anyelement</type>) |
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@ -7293,17 +7325,17 @@ SELECT pg_type_is_visible('myschema.widget'::regtype); |
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<row> |
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<row> |
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<entry> |
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<entry> |
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<literal> |
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<literal> |
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<function>array_cat</function> |
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<function>array_prepend</function> |
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(<type>anyarray</type>, <type>anyarray</type>) |
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(<type>anyelement</type>, <type>anyarray</type>) |
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</literal> |
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</literal> |
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</entry> |
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</entry> |
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<entry><type>anyarray</type></entry> |
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<entry><type>anyarray</type></entry> |
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<entry> |
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<entry> |
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concatenate two arrays, returning <literal>NULL</literal> |
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append an element to the beginning of an array, returning |
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for <literal>NULL</literal> inputs |
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<literal>NULL</literal> for <literal>NULL</literal> inputs |
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</entry> |
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</entry> |
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<entry><literal>array_cat(ARRAY[1,2,3], ARRAY[4,5,6])</literal></entry> |
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<entry><literal>array_prepend(1, ARRAY[2,3])</literal></entry> |
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<entry><literal>{1,2,3,4,5,6}</literal></entry> |
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<entry><literal>{1,2,3}</literal></entry> |
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</row> |
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</row> |
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<row> |
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<row> |
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<entry> |
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<entry> |
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@ -7338,17 +7370,17 @@ SELECT pg_type_is_visible('myschema.widget'::regtype); |
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<row> |
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<row> |
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<entry> |
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<entry> |
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<literal> |
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<literal> |
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<function>array_prepend</function> |
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<function>array_upper</function> |
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(<type>anyelement</type>, <type>anyarray</type>) |
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(<type>anyarray</type>, <type>integer</type>) |
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</literal> |
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</literal> |
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</entry> |
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</entry> |
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<entry><type>anyarray</type></entry> |
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<entry><type>integer</type></entry> |
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<entry> |
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<entry> |
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append an element to the beginning of an array, returning |
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returns upper bound of the requested array dimension, returning |
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<literal>NULL</literal> for <literal>NULL</literal> inputs |
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<literal>NULL</literal> for <literal>NULL</literal> inputs |
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</entry> |
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</entry> |
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<entry><literal>array_prepend(1, ARRAY[2,3])</literal></entry> |
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<entry><literal>array_upper(ARRAY[1,2,3,4], 1)</literal></entry> |
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<entry><literal>{1,2,3}</literal></entry> |
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<entry><literal>4</literal></entry> |
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</row> |
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</row> |
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<row> |
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<row> |
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<entry> |
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<entry> |
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@ -7362,23 +7394,8 @@ SELECT pg_type_is_visible('myschema.widget'::regtype); |
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concatenates array elements using provided delimiter, returning |
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concatenates array elements using provided delimiter, returning |
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<literal>NULL</literal> for <literal>NULL</literal> inputs |
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<literal>NULL</literal> for <literal>NULL</literal> inputs |
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</entry> |
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</entry> |
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<entry><literal>array_to_string(array[1.1,2.2,3.3]::numeric(4,2)[],'~^~')</literal></entry> |
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<entry><literal>array_to_string(array[1, 2, 3], '~^~')</literal></entry> |
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<entry><literal>1.10~^~2.20~^~3.30</literal></entry> |
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<entry><literal>1~^~2~^~3</literal></entry> |
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</row> |
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<row> |
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<entry> |
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<literal> |
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<function>array_upper</function> |
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(<type>anyarray</type>, <type>integer</type>) |
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</literal> |
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</entry> |
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<entry><type>integer</type></entry> |
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<entry> |
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returns upper bound of the requested array dimension, returning |
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<literal>NULL</literal> for <literal>NULL</literal> inputs |
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</entry> |
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<entry><literal>array_upper(array_append(ARRAY[1,2,3], 4), 1)</literal></entry> |
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<entry><literal>4</literal></entry> |
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</row> |
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</row> |
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<row> |
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<row> |
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<entry> |
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<entry> |
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@ -7392,8 +7409,8 @@ SELECT pg_type_is_visible('myschema.widget'::regtype); |
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splits string into array elements using provided delimiter, returning |
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splits string into array elements using provided delimiter, returning |
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<literal>NULL</literal> for <literal>NULL</literal> inputs |
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<literal>NULL</literal> for <literal>NULL</literal> inputs |
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</entry> |
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</entry> |
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<entry><literal>string_to_array('1.10~^~2.20~^~3.30','~^~')::float8[]</literal></entry> |
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<entry><literal>string_to_array( 'xx~^~yy~^~zz', '~^~')</literal></entry> |
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<entry><literal>{1.1,2.2,3.3}</literal></entry> |
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<entry><literal>{xx,yy,zz}</literal></entry> |
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</row> |
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</row> |
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</tbody> |
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</tbody> |
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</tgroup> |
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</tgroup> |
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Tom Lane
22 years ago