<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML
><HEAD
><TITLE
>Arrays</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
REV="MADE"
HREF="mailto:pgsql-docs@postgresql.org"><LINK
REL="HOME"
TITLE="PostgreSQL 7.4.1 Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="Data Types"
HREF="datatype.html"><LINK
REL="PREVIOUS"
TITLE="Bit String Types"
HREF="datatype-bit.html"><LINK
REL="NEXT"
TITLE="Object Identifier Types"
HREF="datatype-oid.html"><LINK
REL="STYLESHEET"
TYPE="text/css"
HREF="stylesheet.css"><META
NAME="creation"
CONTENT="2003-12-22T03:48:47"></HEAD
><BODY
CLASS="SECT1"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="5"
ALIGN="center"
VALIGN="bottom"
>PostgreSQL 7.4.1 Documentation</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
HREF="datatype-bit.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
HREF="datatype.html"
>Fast Backward</A
></TD
><TD
WIDTH="60%"
ALIGN="center"
VALIGN="bottom"
>Chapter 8. Data Types</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="top"
><A
HREF="datatype.html"
>Fast Forward</A
></TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="top"
><A
HREF="datatype-oid.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="ARRAYS"
>8.10. Arrays</A
></H1
><A
NAME="AEN5125"
></A
><P
> <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> allows columns of a table to be
defined as variable-length multidimensional arrays. Arrays of any
built-in type or user-defined type can be created.
</P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN5129"
>8.10.1. Declaration of Array Types</A
></H2
><P
> To illustrate the use of array types, we create this table:
</P><PRE
CLASS="PROGRAMLISTING"
>CREATE TABLE sal_emp (
name text,
pay_by_quarter integer[],
schedule text[][]
);</PRE
><P>
As shown, an array data type is named by appending square brackets
(<TT
CLASS="LITERAL"
>[]</TT
>) to the data type name of the array elements. The
above command will create a table named
<TT
CLASS="STRUCTNAME"
>sal_emp</TT
> with a column of type
<TT
CLASS="TYPE"
>text</TT
> (<TT
CLASS="STRUCTFIELD"
>name</TT
>), a
one-dimensional array of type <TT
CLASS="TYPE"
>integer</TT
>
(<TT
CLASS="STRUCTFIELD"
>pay_by_quarter</TT
>), which represents the
employee's salary by quarter, and a two-dimensional array of
<TT
CLASS="TYPE"
>text</TT
> (<TT
CLASS="STRUCTFIELD"
>schedule</TT
>), which
represents the employee's weekly schedule.
</P
><P
> The syntax for <TT
CLASS="COMMAND"
>CREATE TABLE</TT
> allows the exact size of
arrays to be specified, for example:
</P><PRE
CLASS="PROGRAMLISTING"
>CREATE TABLE tictactoe (
squares integer[3][3]
);</PRE
><P>
However, the current implementation does not enforce the array size
limits --- the behavior is the same as for arrays of unspecified
length.
</P
><P
> Actually, the current implementation does not enforce the declared
number of dimensions either. Arrays of a particular element type are
all considered to be of the same type, regardless of size or number
of dimensions. So, declaring number of dimensions or sizes in
<TT
CLASS="COMMAND"
>CREATE TABLE</TT
> is simply documentation, it does not
affect runtime behavior.
</P
><P
> An alternative, SQL99-standard syntax may be used for one-dimensional arrays.
<TT
CLASS="STRUCTFIELD"
>pay_by_quarter</TT
> could have been defined as:
</P><PRE
CLASS="PROGRAMLISTING"
> pay_by_quarter integer ARRAY[4],</PRE
><P>
This syntax requires an integer constant to denote the array size.
As before, however, <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> does not enforce the
size restriction.
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN5150"
>8.10.2. Array Value Input</A
></H2
><A
NAME="AEN5152"
></A
><P
> To write an array value as a literal constant, enclose the element
values within curly braces and separate them by commas. (If you
know C, this is not unlike the C syntax for initializing
structures.) You may put double quotes around any element value,
and must do so if it contains commas or curly braces. (More
details appear below.) Thus, the general format of an array
constant is the following:
</P><PRE
CLASS="SYNOPSIS"
>'{ <VAR
CLASS="REPLACEABLE"
>val1</VAR
> <VAR
CLASS="REPLACEABLE"
>delim</VAR
> <VAR
CLASS="REPLACEABLE"
>val2</VAR
> <VAR
CLASS="REPLACEABLE"
>delim</VAR
> ... }'</PRE
><P>
where <VAR
CLASS="REPLACEABLE"
>delim</VAR
> is the delimiter character
for the type, as recorded in its <TT
CLASS="LITERAL"
>pg_type</TT
> entry.
(For all built-in types, this is the comma character
<SPAN
CLASS="QUOTE"
>"<TT
CLASS="LITERAL"
>,</TT
>"</SPAN
>.) Each
<VAR
CLASS="REPLACEABLE"
>val</VAR
> is either a constant of the array
element type, or a subarray. An example of an array constant is
</P><PRE
CLASS="PROGRAMLISTING"
>'{{1,2,3},{4,5,6},{7,8,9}}'</PRE
><P>
This constant is a two-dimensional, 3-by-3 array consisting of
three subarrays of integers.
</P
><P
> (These kinds of array constants are actually only a special case of
the generic type constants discussed in <A
HREF="sql-syntax.html#SQL-SYNTAX-CONSTANTS-GENERIC"
>Section 4.1.2.4</A
>. The constant is initially
treated as a string and passed to the array input conversion
routine. An explicit type specification might be necessary.)
</P
><P
> Now we can show some <TT
CLASS="COMMAND"
>INSERT</TT
> statements.
</P><PRE
CLASS="PROGRAMLISTING"
>INSERT INTO sal_emp
VALUES ('Bill',
'{10000, 10000, 10000, 10000}',
'{{"meeting", "lunch"}, {}}');
INSERT INTO sal_emp
VALUES ('Carol',
'{20000, 25000, 25000, 25000}',
'{{"talk", "consult"}, {"meeting"}}');</PRE
><P>
</P
><P
> A limitation of the present array implementation is that individual
elements of an array cannot be SQL null values. The entire array
can be set to null, but you can't have an array with some elements
null and some not.
</P
><P
> This can lead to surprising results. For example, the result of the
previous two inserts looks like this:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT * FROM sal_emp;
name | pay_by_quarter | schedule
-------+---------------------------+--------------------
Bill | {10000,10000,10000,10000} | {{meeting},{""}}
Carol | {20000,25000,25000,25000} | {{talk},{meeting}}
(2 rows)</PRE
><P>
Because the <TT
CLASS="LITERAL"
>[2][2]</TT
> element of
<TT
CLASS="STRUCTFIELD"
>schedule</TT
> is missing in each of the
<TT
CLASS="COMMAND"
>INSERT</TT
> statements, the <TT
CLASS="LITERAL"
>[1][2]</TT
>
element is discarded.
</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> Fixing this is on the to-do list.
</P
></BLOCKQUOTE
></DIV
><P
> The <TT
CLASS="LITERAL"
>ARRAY</TT
> expression syntax may also be used:
</P><PRE
CLASS="PROGRAMLISTING"
>INSERT INTO sal_emp
VALUES ('Bill',
ARRAY[10000, 10000, 10000, 10000],
ARRAY[['meeting', 'lunch'], ['','']]);
INSERT INTO sal_emp
VALUES ('Carol',
ARRAY[20000, 25000, 25000, 25000],
ARRAY[['talk', 'consult'], ['meeting', '']]);
SELECT * FROM sal_emp;
name | pay_by_quarter | schedule
-------+---------------------------+-------------------------------
Bill | {10000,10000,10000,10000} | {{meeting,lunch},{"",""}}
Carol | {20000,25000,25000,25000} | {{talk,consult},{meeting,""}}
(2 rows)</PRE
><P>
Note that with this syntax, multidimensional arrays must have matching
extents for each dimension. A mismatch causes an error report, rather than
silently discarding values as in the previous case.
For example:
</P><PRE
CLASS="PROGRAMLISTING"
>INSERT INTO sal_emp
VALUES ('Carol',
ARRAY[20000, 25000, 25000, 25000],
ARRAY[['talk', 'consult'], ['meeting']]);
ERROR: multidimensional arrays must have array expressions with matching dimensions</PRE
><P>
Also notice that the array elements are ordinary SQL constants or
expressions; for instance, string literals are single quoted, instead of
double quoted as they would be in an array literal. The <TT
CLASS="LITERAL"
>ARRAY</TT
>
expression syntax is discussed in more detail in <A
HREF="sql-expressions.html#SQL-SYNTAX-ARRAY-CONSTRUCTORS"
>Section 4.2.10</A
>.
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN5187"
>8.10.3. Accessing Arrays</A
></H2
><P
> Now, we can run some queries on the table.
First, we show how to access a single element of an array at a time.
This query retrieves the names of the employees whose pay changed in
the second quarter:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT name FROM sal_emp WHERE pay_by_quarter[1] <> pay_by_quarter[2];
name
-------
Carol
(1 row)</PRE
><P>
The array subscript numbers are written within square brackets.
By default <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> uses the
one-based numbering convention for arrays, that is,
an array of <VAR
CLASS="REPLACEABLE"
>n</VAR
> elements starts with <TT
CLASS="LITERAL"
>array[1]</TT
> and
ends with <TT
CLASS="LITERAL"
>array[<VAR
CLASS="REPLACEABLE"
>n</VAR
>]</TT
>.
</P
><P
> This query retrieves the third quarter pay of all employees:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT pay_by_quarter[3] FROM sal_emp;
pay_by_quarter
----------------
10000
25000
(2 rows)</PRE
><P>
</P
><P
> We can also access arbitrary rectangular slices of an array, or
subarrays. An array slice is denoted by writing
<TT
CLASS="LITERAL"
><VAR
CLASS="REPLACEABLE"
>lower-bound</VAR
>:<VAR
CLASS="REPLACEABLE"
>upper-bound</VAR
></TT
>
for one or more array dimensions. For example, this query retrieves the first
item on Bill's schedule for the first two days of the week:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT schedule[1:2][1:1] FROM sal_emp WHERE name = 'Bill';
schedule
--------------------
{{meeting},{""}}
(1 row)</PRE
><P>
We could also have written
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT schedule[1:2][1] FROM sal_emp WHERE name = 'Bill';</PRE
><P>
with the same result. An array subscripting operation is always taken to
represent an array slice if any of the subscripts are written in the form
<TT
CLASS="LITERAL"
><VAR
CLASS="REPLACEABLE"
>lower</VAR
>:<VAR
CLASS="REPLACEABLE"
>upper</VAR
></TT
>.
A lower bound of 1 is assumed for any subscript where only one value
is specified, as in this example:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT schedule[1:2][2] FROM sal_emp WHERE name = 'Bill';
schedule
---------------------------
{{meeting,lunch},{"",""}}
(1 row)</PRE
><P>
</P
><P
> The current dimensions of any array value can be retrieved with the
<CODE
CLASS="FUNCTION"
>array_dims</CODE
> function:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT array_dims(schedule) FROM sal_emp WHERE name = 'Carol';
array_dims
------------
[1:2][1:1]
(1 row)</PRE
><P>
<CODE
CLASS="FUNCTION"
>array_dims</CODE
> produces a <TT
CLASS="TYPE"
>text</TT
> result,
which is convenient for people to read but perhaps not so convenient
for programs. Dimensions can also be retrieved with
<CODE
CLASS="FUNCTION"
>array_upper</CODE
> and <CODE
CLASS="FUNCTION"
>array_lower</CODE
>,
which return the upper and lower bound of a
specified array dimension, respectively.
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT array_upper(schedule, 1) FROM sal_emp WHERE name = 'Carol';
array_upper
-------------
2
(1 row)</PRE
><P>
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN5216"
>8.10.4. Modifying Arrays</A
></H2
><P
> An array value can be replaced completely:
</P><PRE
CLASS="PROGRAMLISTING"
>UPDATE sal_emp SET pay_by_quarter = '{25000,25000,27000,27000}'
WHERE name = 'Carol';</PRE
><P>
or using the <TT
CLASS="LITERAL"
>ARRAY</TT
> expression syntax:
</P><PRE
CLASS="PROGRAMLISTING"
>UPDATE sal_emp SET pay_by_quarter = ARRAY[25000,25000,27000,27000]
WHERE name = 'Carol';</PRE
><P>
An array may also be updated at a single element:
</P><PRE
CLASS="PROGRAMLISTING"
>UPDATE sal_emp SET pay_by_quarter[4] = 15000
WHERE name = 'Bill';</PRE
><P>
or updated in a slice:
</P><PRE
CLASS="PROGRAMLISTING"
>UPDATE sal_emp SET pay_by_quarter[1:2] = '{27000,27000}'
WHERE name = 'Carol';</PRE
><P>
</P
><P
> A stored array value can be enlarged by assigning to an element adjacent to
those already present, or by assigning to a slice that is adjacent
to or overlaps the data already present. For example, if array
<TT
CLASS="LITERAL"
>myarray</TT
> currently has 4 elements, it will have five
elements after an update that assigns to <TT
CLASS="LITERAL"
>myarray[5]</TT
>.
Currently, enlargement in this fashion is only allowed for one-dimensional
arrays, not multidimensional arrays.
</P
><P
> Array slice assignment allows creation of arrays that do not use one-based
subscripts. For example one might assign to <TT
CLASS="LITERAL"
>myarray[-2:7]</TT
> to
create an array with subscript values running from -2 to 7.
</P
><P
> New array values can also be constructed by using the concatenation operator,
<TT
CLASS="LITERAL"
>||</TT
>.
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT ARRAY[1,2] || ARRAY[3,4];
?column?
-----------
{1,2,3,4}
(1 row)
SELECT ARRAY[5,6] || ARRAY[[1,2],[3,4]];
?column?
---------------------
{{5,6},{1,2},{3,4}}
(1 row)</PRE
><P>
</P
><P
> The concatenation operator allows a single element to be pushed on to the
beginning or end of a one-dimensional array. It also accepts two
<VAR
CLASS="REPLACEABLE"
>N</VAR
>-dimensional arrays, or an <VAR
CLASS="REPLACEABLE"
>N</VAR
>-dimensional
and an <VAR
CLASS="REPLACEABLE"
>N+1</VAR
>-dimensional array.
</P
><P
> When a single element is pushed on to the beginning of a one-dimensional
array, the result is an array with a lower bound subscript equal to
the right-hand operand's lower bound subscript, minus one. When a single
element is pushed on to the end of a one-dimensional array, the result is
an array retaining the lower bound of the left-hand operand. For example:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT array_dims(1 || ARRAY[2,3]);
array_dims
------------
[0:2]
(1 row)
SELECT array_dims(ARRAY[1,2] || 3);
array_dims
------------
[1:3]
(1 row)</PRE
><P>
</P
><P
> When two arrays with an equal number of dimensions are concatenated, the
result retains the lower bound subscript of the left-hand operand's outer
dimension. The result is an array comprising every element of the left-hand
operand followed by every element of the right-hand operand. For example:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT array_dims(ARRAY[1,2] || ARRAY[3,4,5]);
array_dims
------------
[1:5]
(1 row)
SELECT array_dims(ARRAY[[1,2],[3,4]] || ARRAY[[5,6],[7,8],[9,0]]);
array_dims
------------
[1:5][1:2]
(1 row)</PRE
><P>
</P
><P
> When an <VAR
CLASS="REPLACEABLE"
>N</VAR
>-dimensional array is pushed on to the beginning
or end of an <VAR
CLASS="REPLACEABLE"
>N+1</VAR
>-dimensional array, the result is
analogous to the element-array case above. Each <VAR
CLASS="REPLACEABLE"
>N</VAR
>-dimensional
sub-array is essentially an element of the <VAR
CLASS="REPLACEABLE"
>N+1</VAR
>-dimensional
array's outer dimension. For example:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT array_dims(ARRAY[1,2] || ARRAY[[3,4],[5,6]]);
array_dims
------------
[0:2][1:2]
(1 row)</PRE
><P>
</P
><P
> An array can also be constructed by using the functions
<CODE
CLASS="FUNCTION"
>array_prepend</CODE
>, <CODE
CLASS="FUNCTION"
>array_append</CODE
>,
or <CODE
CLASS="FUNCTION"
>array_cat</CODE
>. The first two only support one-dimensional
arrays, but <CODE
CLASS="FUNCTION"
>array_cat</CODE
> supports multidimensional arrays.
Note that the concatenation operator discussed above is preferred over
direct use of these functions. In fact, the functions are primarily for use
in implementing the concatenation operator. However, they may be directly
useful in the creation of user-defined aggregates. Some examples:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT array_prepend(1, ARRAY[2,3]);
array_prepend
---------------
{1,2,3}
(1 row)
SELECT array_append(ARRAY[1,2], 3);
array_append
--------------
{1,2,3}
(1 row)
SELECT array_cat(ARRAY[1,2], ARRAY[3,4]);
array_cat
-----------
{1,2,3,4}
(1 row)
SELECT array_cat(ARRAY[[1,2],[3,4]], ARRAY[5,6]);
array_cat
---------------------
{{1,2},{3,4},{5,6}}
(1 row)
SELECT array_cat(ARRAY[5,6], ARRAY[[1,2],[3,4]]);
array_cat
---------------------
{{5,6},{1,2},{3,4}}</PRE
><P>
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN5252"
>8.10.5. Searching in Arrays</A
></H2
><P
> To search for a value in an array, you must check each value of the
array. This can be done by hand, if you know the size of the array.
For example:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT * FROM sal_emp WHERE pay_by_quarter[1] = 10000 OR
pay_by_quarter[2] = 10000 OR
pay_by_quarter[3] = 10000 OR
pay_by_quarter[4] = 10000;</PRE
><P>
However, this quickly becomes tedious for large arrays, and is not
helpful if the size of the array is uncertain. An alternative method is
described in <A
HREF="functions-comparisons.html"
>Section 9.17</A
>. The above
query could be replaced by:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT * FROM sal_emp WHERE 10000 = ANY (pay_by_quarter);</PRE
><P>
In addition, you could find rows where the array had all values
equal to 10000 with:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT * FROM sal_emp WHERE 10000 = ALL (pay_by_quarter);</PRE
><P>
</P
><DIV
CLASS="TIP"
><BLOCKQUOTE
CLASS="TIP"
><P
><B
>Tip: </B
> Arrays are not sets; searching for specific array elements
may be a sign of database misdesign. Consider
using a separate table with a row for each item that would be an
array element. This will be easier to search, and is likely to
scale up better to large numbers of elements.
</P
></BLOCKQUOTE
></DIV
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN5261"
>8.10.6. Array Input and Output Syntax</A
></H2
><P
> The external text representation of an array value consists of items that
are interpreted according to the I/O conversion rules for the array's
element type, plus decoration that indicates the array structure.
The decoration consists of curly braces (<TT
CLASS="LITERAL"
>{</TT
> and <TT
CLASS="LITERAL"
>}</TT
>)
around the array value plus delimiter characters between adjacent items.
The delimiter character is usually a comma (<TT
CLASS="LITERAL"
>,</TT
>) but can be
something else: it is determined by the <TT
CLASS="LITERAL"
>typdelim</TT
> setting
for the array's element type. (Among the standard data types provided
in the <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> distribution, type
<TT
CLASS="LITERAL"
>box</TT
> uses a semicolon (<TT
CLASS="LITERAL"
>;</TT
>) but all the others
use comma.) In a multidimensional array, each dimension (row, plane,
cube, etc.) gets its own level of curly braces, and delimiters
must be written between adjacent curly-braced entities of the same level.
You may write whitespace before a left brace, after a right
brace, or before any individual item string. Whitespace after an item
is not ignored, however: after skipping leading whitespace, everything
up to the next right brace or delimiter is taken as the item value.
</P
><P
> As shown previously, when writing an array value you may write double
quotes around any individual array
element. You <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>must</I
></SPAN
> do so if the element value would otherwise
confuse the array-value parser. For example, elements containing curly
braces, commas (or whatever the delimiter character is), double quotes,
backslashes, or leading white space must be double-quoted. To put a double
quote or backslash in a quoted array element value, precede it with a
backslash.
Alternatively, you can use backslash-escaping to protect all data characters
that would otherwise be taken as array syntax or ignorable white space.
</P
><P
> The array output routine will put double quotes around element values
if they are empty strings or contain curly braces, delimiter characters,
double quotes, backslashes, or white space. Double quotes and backslashes
embedded in element values will be backslash-escaped. For numeric
data types it is safe to assume that double quotes will never appear, but
for textual data types one should be prepared to cope with either presence
or absence of quotes. (This is a change in behavior from pre-7.2
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> releases.)
</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> Remember that what you write in an SQL command will first be interpreted
as a string literal, and then as an array. This doubles the number of
backslashes you need. For example, to insert a <TT
CLASS="TYPE"
>text</TT
> array
value containing a backslash and a double quote, you'd need to write
</P><PRE
CLASS="PROGRAMLISTING"
>INSERT ... VALUES ('{"\\\\","\\""}');</PRE
><P>
The string-literal processor removes one level of backslashes, so that
what arrives at the array-value parser looks like <TT
CLASS="LITERAL"
>{"\\","\""}</TT
>.
In turn, the strings fed to the <TT
CLASS="TYPE"
>text</TT
> data type's input routine
become <TT
CLASS="LITERAL"
>\</TT
> and <TT
CLASS="LITERAL"
>"</TT
> respectively. (If we were working
with a data type whose input routine also treated backslashes specially,
<TT
CLASS="TYPE"
>bytea</TT
> for example, we might need as many as eight backslashes
in the command to get one backslash into the stored array element.)
</P
></BLOCKQUOTE
></DIV
><DIV
CLASS="TIP"
><BLOCKQUOTE
CLASS="TIP"
><P
><B
>Tip: </B
> The <TT
CLASS="LITERAL"
>ARRAY</TT
> constructor syntax is often easier to work with
than the array-literal syntax when writing array values in SQL commands.
In <TT
CLASS="LITERAL"
>ARRAY</TT
>, individual element values are written the same way
they would be written when not members of an array.
</P
></BLOCKQUOTE
></DIV
></DIV
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="datatype-bit.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="datatype-oid.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Bit String Types</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="datatype.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Object Identifier Types</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>
