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><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="FUNCTIONS-ARRAY"
>9.17. Array Functions and Operators</A
></H1
><P
> <A
HREF="functions-array.html#ARRAY-OPERATORS-TABLE"
>Table 9-40</A
> shows the operators
available for array types.
</P
><DIV
CLASS="TABLE"
><A
NAME="ARRAY-OPERATORS-TABLE"
></A
><P
><B
>Table 9-40. Array Operators</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><COL><THEAD
><TR
><TH
>Operator</TH
><TH
>Description</TH
><TH
>Example</TH
><TH
>Result</TH
></TR
></THEAD
><TBODY
><TR
><TD
> <TT
CLASS="LITERAL"
>=</TT
> </TD
><TD
>equal</TD
><TD
><TT
CLASS="LITERAL"
>ARRAY[1.1,2.1,3.1]::int[] = ARRAY[1,2,3]</TT
></TD
><TD
><TT
CLASS="LITERAL"
>t</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
><></TT
> </TD
><TD
>not equal</TD
><TD
><TT
CLASS="LITERAL"
>ARRAY[1,2,3] <> ARRAY[1,2,4]</TT
></TD
><TD
><TT
CLASS="LITERAL"
>t</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
><</TT
> </TD
><TD
>less than</TD
><TD
><TT
CLASS="LITERAL"
>ARRAY[1,2,3] < ARRAY[1,2,4]</TT
></TD
><TD
><TT
CLASS="LITERAL"
>t</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
>></TT
> </TD
><TD
>greater than</TD
><TD
><TT
CLASS="LITERAL"
>ARRAY[1,4,3] > ARRAY[1,2,4]</TT
></TD
><TD
><TT
CLASS="LITERAL"
>t</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
><=</TT
> </TD
><TD
>less than or equal</TD
><TD
><TT
CLASS="LITERAL"
>ARRAY[1,2,3] <= ARRAY[1,2,3]</TT
></TD
><TD
><TT
CLASS="LITERAL"
>t</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
>>=</TT
> </TD
><TD
>greater than or equal</TD
><TD
><TT
CLASS="LITERAL"
>ARRAY[1,4,3] >= ARRAY[1,4,3]</TT
></TD
><TD
><TT
CLASS="LITERAL"
>t</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
>@></TT
> </TD
><TD
>contains</TD
><TD
><TT
CLASS="LITERAL"
>ARRAY[1,4,3] @> ARRAY[3,1]</TT
></TD
><TD
><TT
CLASS="LITERAL"
>t</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
><@</TT
> </TD
><TD
>is contained by</TD
><TD
><TT
CLASS="LITERAL"
>ARRAY[2,7] <@ ARRAY[1,7,4,2,6]</TT
></TD
><TD
><TT
CLASS="LITERAL"
>t</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
>&&</TT
> </TD
><TD
>overlap (have elements in common)</TD
><TD
><TT
CLASS="LITERAL"
>ARRAY[1,4,3] && ARRAY[2,1]</TT
></TD
><TD
><TT
CLASS="LITERAL"
>t</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
>||</TT
> </TD
><TD
>array-to-array concatenation</TD
><TD
><TT
CLASS="LITERAL"
>ARRAY[1,2,3] || ARRAY[4,5,6]</TT
></TD
><TD
><TT
CLASS="LITERAL"
>{1,2,3,4,5,6}</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
>||</TT
> </TD
><TD
>array-to-array concatenation</TD
><TD
><TT
CLASS="LITERAL"
>ARRAY[1,2,3] || ARRAY[[4,5,6],[7,8,9]]</TT
></TD
><TD
><TT
CLASS="LITERAL"
>{{1,2,3},{4,5,6},{7,8,9}}</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
>||</TT
> </TD
><TD
>element-to-array concatenation</TD
><TD
><TT
CLASS="LITERAL"
>3 || ARRAY[4,5,6]</TT
></TD
><TD
><TT
CLASS="LITERAL"
>{3,4,5,6}</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
>||</TT
> </TD
><TD
>array-to-element concatenation</TD
><TD
><TT
CLASS="LITERAL"
>ARRAY[4,5,6] || 7</TT
></TD
><TD
><TT
CLASS="LITERAL"
>{4,5,6,7}</TT
></TD
></TR
></TBODY
></TABLE
></DIV
><P
> Array comparisons compare the array contents element-by-element,
using the default B-Tree comparison function for the element data type.
In multidimensional arrays the elements are visited in row-major order
(last subscript varies most rapidly).
If the contents of two arrays are equal but the dimensionality is
different, the first difference in the dimensionality information
determines the sort order. (This is a change from versions of
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> prior to 8.2: older versions would claim
that two arrays with the same contents were equal, even if the
number of dimensions or subscript ranges were different.)
</P
><P
> See <A
HREF="arrays.html"
>Section 8.14</A
> for more details about array operator
behavior.
</P
><P
> <A
HREF="functions-array.html#ARRAY-FUNCTIONS-TABLE"
>Table 9-41</A
> shows the functions
available for use with array types. See <A
HREF="arrays.html"
>Section 8.14</A
>
for more information and examples of the use of these functions.
</P
><A
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></A
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><DIV
CLASS="TABLE"
><A
NAME="ARRAY-FUNCTIONS-TABLE"
></A
><P
><B
>Table 9-41. Array Functions</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><COL><COL><THEAD
><TR
><TH
>Function</TH
><TH
>Return Type</TH
><TH
>Description</TH
><TH
>Example</TH
><TH
>Result</TH
></TR
></THEAD
><TBODY
><TR
><TD
> <TT
CLASS="LITERAL"
> <CODE
CLASS="FUNCTION"
>array_append</CODE
>(<TT
CLASS="TYPE"
>anyarray</TT
>, <TT
CLASS="TYPE"
>anyelement</TT
>)
</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>anyarray</TT
></TD
><TD
>append an element to the end of an array</TD
><TD
><TT
CLASS="LITERAL"
>array_append(ARRAY[1,2], 3)</TT
></TD
><TD
><TT
CLASS="LITERAL"
>{1,2,3}</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
> <CODE
CLASS="FUNCTION"
>array_cat</CODE
>(<TT
CLASS="TYPE"
>anyarray</TT
>, <TT
CLASS="TYPE"
>anyarray</TT
>)
</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>anyarray</TT
></TD
><TD
>concatenate two arrays</TD
><TD
><TT
CLASS="LITERAL"
>array_cat(ARRAY[1,2,3], ARRAY[4,5])</TT
></TD
><TD
><TT
CLASS="LITERAL"
>{1,2,3,4,5}</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
> <CODE
CLASS="FUNCTION"
>array_ndims</CODE
>(<TT
CLASS="TYPE"
>anyarray</TT
>)
</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>int</TT
></TD
><TD
>returns the number of dimensions of the array</TD
><TD
><TT
CLASS="LITERAL"
>array_ndims(ARRAY[[1,2,3], [4,5,6]])</TT
></TD
><TD
><TT
CLASS="LITERAL"
>2</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
> <CODE
CLASS="FUNCTION"
>array_dims</CODE
>(<TT
CLASS="TYPE"
>anyarray</TT
>)
</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>returns a text representation of array's dimensions</TD
><TD
><TT
CLASS="LITERAL"
>array_dims(ARRAY[[1,2,3], [4,5,6]])</TT
></TD
><TD
><TT
CLASS="LITERAL"
>[1:2][1:3]</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
> <CODE
CLASS="FUNCTION"
>array_fill</CODE
>(<TT
CLASS="TYPE"
>anyelement</TT
>, <TT
CLASS="TYPE"
>int[]</TT
>,
[<SPAN
CLASS="OPTIONAL"
>, <TT
CLASS="TYPE"
>int[]</TT
></SPAN
>])
</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>anyarray</TT
></TD
><TD
>returns an array initialized with supplied value and
dimensions, optionally with lower bounds other than 1</TD
><TD
><TT
CLASS="LITERAL"
>array_fill(7, ARRAY[3], ARRAY[2])</TT
></TD
><TD
><TT
CLASS="LITERAL"
>[2:4]={7,7,7}</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
> <CODE
CLASS="FUNCTION"
>array_length</CODE
>(<TT
CLASS="TYPE"
>anyarray</TT
>, <TT
CLASS="TYPE"
>int</TT
>)
</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>int</TT
></TD
><TD
>returns the length of the requested array dimension</TD
><TD
><TT
CLASS="LITERAL"
>array_length(array[1,2,3], 1)</TT
></TD
><TD
><TT
CLASS="LITERAL"
>3</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
> <CODE
CLASS="FUNCTION"
>array_lower</CODE
>(<TT
CLASS="TYPE"
>anyarray</TT
>, <TT
CLASS="TYPE"
>int</TT
>)
</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>int</TT
></TD
><TD
>returns lower bound of the requested array dimension</TD
><TD
><TT
CLASS="LITERAL"
>array_lower('[0:2]={1,2,3}'::int[], 1)</TT
></TD
><TD
><TT
CLASS="LITERAL"
>0</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
> <CODE
CLASS="FUNCTION"
>array_prepend</CODE
>(<TT
CLASS="TYPE"
>anyelement</TT
>, <TT
CLASS="TYPE"
>anyarray</TT
>)
</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>anyarray</TT
></TD
><TD
>append an element to the beginning of an array</TD
><TD
><TT
CLASS="LITERAL"
>array_prepend(1, ARRAY[2,3])</TT
></TD
><TD
><TT
CLASS="LITERAL"
>{1,2,3}</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
> <CODE
CLASS="FUNCTION"
>array_to_string</CODE
>(<TT
CLASS="TYPE"
>anyarray</TT
>, <TT
CLASS="TYPE"
>text</TT
>)
</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>concatenates array elements using supplied delimiter</TD
><TD
><TT
CLASS="LITERAL"
>array_to_string(ARRAY[1, 2, 3], '~^~')</TT
></TD
><TD
><TT
CLASS="LITERAL"
>1~^~2~^~3</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
> <CODE
CLASS="FUNCTION"
>array_upper</CODE
>(<TT
CLASS="TYPE"
>anyarray</TT
>, <TT
CLASS="TYPE"
>int</TT
>)
</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>int</TT
></TD
><TD
>returns upper bound of the requested array dimension</TD
><TD
><TT
CLASS="LITERAL"
>array_upper(ARRAY[1,2,3,4], 1)</TT
></TD
><TD
><TT
CLASS="LITERAL"
>4</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
> <CODE
CLASS="FUNCTION"
>string_to_array</CODE
>(<TT
CLASS="TYPE"
>text</TT
>, <TT
CLASS="TYPE"
>text</TT
>)
</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>text[]</TT
></TD
><TD
>splits string into array elements using supplied delimiter</TD
><TD
><TT
CLASS="LITERAL"
>string_to_array('xx~^~yy~^~zz', '~^~')</TT
></TD
><TD
><TT
CLASS="LITERAL"
>{xx,yy,zz}</TT
></TD
></TR
><TR
><TD
> <TT
CLASS="LITERAL"
> <CODE
CLASS="FUNCTION"
>unnest</CODE
>(<TT
CLASS="TYPE"
>anyarray</TT
>)
</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>setof anyelement</TT
></TD
><TD
>expand an array to a set of rows</TD
><TD
><TT
CLASS="LITERAL"
>unnest(ARRAY[1,2])</TT
></TD
><TD
><TT
CLASS="LITERAL"
>1</TT
><P
><TT
CLASS="LITERAL"
>2</TT
></P
> (2 rows)</TD
></TR
></TBODY
></TABLE
></DIV
><P
> See also <A
HREF="functions-aggregate.html"
>Section 9.18</A
> about the aggregate
function <CODE
CLASS="FUNCTION"
>array_agg</CODE
> for use with arrays.
</P
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