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Diffstat (limited to 'doc/src/sgml/array.sgml')
| -rw-r--r-- | doc/src/sgml/array.sgml | 34 |
1 files changed, 33 insertions, 1 deletions
diff --git a/doc/src/sgml/array.sgml b/doc/src/sgml/array.sgml index 99cfde85f2c..1696d61c257 100644 --- a/doc/src/sgml/array.sgml +++ b/doc/src/sgml/array.sgml @@ -1,4 +1,4 @@ -<!-- $Header: /cvsroot/pgsql/doc/src/sgml/array.sgml,v 1.17 2001/11/28 20:49:09 petere Exp $ --> +<!-- $Header: /cvsroot/pgsql/doc/src/sgml/array.sgml,v 1.18 2001/11/29 21:02:41 tgl Exp $ --> <chapter id="arrays"> <title>Arrays</title> @@ -248,4 +248,36 @@ SELECT * FROM sal_emp WHERE pay_by_quarter **= 10000; </para> </note> + <formalpara> + <title>Quoting array elements.</title> + <para> + As shown above, when writing an array literal value you may write double + quotes around any individual array + element. You <emphasis>must</> do so if the element value would otherwise + confuse the array-value parser. For example, elements containing curly + braces, commas, double quotes, backslashes, or white space must be + double-quoted. To put a double quote or backslash in an array element + value, precede it with a backslash. + </para> + </formalpara> + + <tip> + <para> + Remember that what you write in an SQL query 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 <type>text</> array + value containing a backslash and a double quote, you'd need to write +<programlisting> +INSERT ... VALUES ('{"\\\\","\\""}'); +</programlisting> + The string-literal processor removes one level of backslashes, so that + what arrives at the array-value parser looks like <literal>{"\\","\""}</>. + In turn, the strings fed to the <type>text</> datatype's input routine + become <literal>\</> and <literal>"</> respectively. (If we were working + with a datatype whose input routine also treated backslashes specially, + <type>bytea</> for example, we might need as many as eight backslashes + in the query to get one backslash into the stored array element.) + </para> + </tip> + </chapter> |