diff options
Diffstat (limited to 'doc/src/sgml/ref/declare.sgml')
| -rw-r--r-- | doc/src/sgml/ref/declare.sgml | 46 |
1 files changed, 26 insertions, 20 deletions
diff --git a/doc/src/sgml/ref/declare.sgml b/doc/src/sgml/ref/declare.sgml index 77c45d90b09..5f481220071 100644 --- a/doc/src/sgml/ref/declare.sgml +++ b/doc/src/sgml/ref/declare.sgml @@ -1,5 +1,5 @@ <!-- -$Header: /cvsroot/pgsql/doc/src/sgml/ref/declare.sgml,v 1.18 2002/05/18 15:44:47 petere Exp $ +$Header: /cvsroot/pgsql/doc/src/sgml/ref/declare.sgml,v 1.19 2003/03/10 03:53:48 tgl Exp $ PostgreSQL documentation --> @@ -47,8 +47,7 @@ DECLARE <replaceable class="parameter">cursorname</replaceable> [ BINARY ] [ INS <term>BINARY</term> <listitem> <para> - Causes the cursor to fetch data in binary - rather than in text format. + Causes the cursor to return data in binary rather than in text format. </para> </listitem> </varlistentry> @@ -70,9 +69,8 @@ DECLARE <replaceable class="parameter">cursorname</replaceable> [ BINARY ] [ INS <term>SCROLL</term> <listitem> <para> - <acronym>SQL92</acronym> keyword indicating that data may be retrieved - in multiple rows per FETCH operation. Since this is allowed at all times - by <productname>PostgreSQL</productname> this keyword has no effect. + Specifies that the cursor may be used to retrieve rows + in a nonsequential fashion (e.g., backwards). </para> </listitem> </varlistentry> @@ -81,10 +79,10 @@ DECLARE <replaceable class="parameter">cursorname</replaceable> [ BINARY ] [ INS <term><replaceable class="parameter">query</replaceable></term> <listitem> <para> - An SQL query which will provide the rows to be governed by the - cursor. - Refer to the SELECT statement for further information about - valid arguments. + A <command>SELECT</> query which will provide the rows to be + returned by the cursor. + Refer to <xref linkend="sql-select" endterm="sql-select-title"> + for further information about valid arguments. </para> </listitem> </varlistentry> @@ -126,6 +124,10 @@ DECLARE <replaceable class="parameter">cursorname</replaceable> [ BINARY ] [ INS </variablelist> </para> + + <para> + The BINARY, INSENSITIVE, and SCROLL keywords may appear in any order. + </para> </refsect2> <refsect2 id="R2-SQL-DECLARE-2"> @@ -193,9 +195,8 @@ ERROR: DECLARE CURSOR may only be used in begin/end transaction blocks </para> <para> - Normal cursors return data in text format, either ASCII or another - encoding scheme depending on how the <productname>PostgreSQL</productname> - backend was built. Since + Normal cursors return data in text format, the same as a <command>SELECT</> + would produce. Since data is stored natively in binary format, the system must do a conversion to produce the text format. In addition, text formats are often larger in size than the corresponding binary format. @@ -228,15 +229,11 @@ ERROR: DECLARE CURSOR may only be used in begin/end transaction blocks representations (e.g., <quote>big-endian</quote> versus <quote>little-endian</quote>), you will probably not want your data returned in binary format. - However, binary cursors may be a - little more efficient since there is less conversion overhead in - the server to client data transfer. <tip> <para> - If you intend to display the data in - ASCII, getting it back in ASCII will save you some - effort on the client side. + If you intend to display the data as text, retrieving it in text form + will save you some effort on the client side. </para> </tip> </para> @@ -250,7 +247,7 @@ ERROR: DECLARE CURSOR may only be used in begin/end transaction blocks </title> <para> - Cursors are only available in transactions. Use to + Cursors are only available within transactions. Use <xref linkend="sql-begin" endterm="sql-begin-title">, <xref linkend="sql-commit" endterm="sql-commit-title"> and @@ -259,6 +256,15 @@ ERROR: DECLARE CURSOR may only be used in begin/end transaction blocks </para> <para> + The <literal>SCROLL</> option should be specified when defining a cursor + that will be used to fetch backwards. This is required by + <acronym>SQL92</acronym>. However, for compatibility with + earlier versions, <productname>PostgreSQL</productname> will allow + backward fetches without <literal>SCROLL</>, if the cursor's query plan + is simple enough that no extra overhead is needed to support it. + </para> + + <para> In <acronym>SQL92</acronym> cursors are only available in embedded <acronym>SQL</acronym> (<acronym>ESQL</acronym>) applications. The <productname>PostgreSQL</productname> backend |