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<REFENTRY ID="SQL-CREATESEQUENCE-1">
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<REFMETA>
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<REFENTRYTITLE>
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CREATE SEQUENCE
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</REFENTRYTITLE>
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<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
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</REFMETA>
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<REFNAMEDIV>
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<REFNAME>
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CREATE SEQUENCE
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</REFNAME>
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<REFPURPOSE>
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Creates a new sequence number generator
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</REFPURPOSE>
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<REFSYNOPSISDIV>
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<REFSYNOPSISDIVINFO>
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<DATE>1998-04-15</DATE>
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</REFSYNOPSISDIVINFO>
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<SYNOPSIS>
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CREATE SEQUENCE <replaceable class="parameter">seqname</replaceable>
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[INCREMENT <replaceable class="parameter">increment</replaceable>]
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[MINVALUE <replaceable class="parameter">minvalue</replaceable>]
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[MAXVALUE <replaceable class="parameter">maxvalue</replaceable>]
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[START <replaceable class="parameter">start</replaceable>]
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[CACHE <replaceable class="parameter">cache</replaceable>]
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[CYCLE]
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</SYNOPSIS>
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<REFSECT2 ID="R2-SQL-CREATESEQUENCE-1">
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<REFSECT2INFO>
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<DATE>1998-04-15</DATE>
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</REFSECT2INFO>
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<TITLE>
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Inputs
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</TITLE>
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<PARA>
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</PARA>
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<VARIABLELIST>
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<VARLISTENTRY>
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<TERM>
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</TERM>
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<LISTITEM>
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<PARA>
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<VARIABLELIST>
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<VARLISTENTRY>
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<TERM>
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<ReturnValue><replaceable class="parameter">seqname</replaceable></ReturnValue>
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</TERM>
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<LISTITEM>
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<PARA>
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The name of a sequence to be created.
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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<VARLISTENTRY>
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<TERM>
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<ReturnValue><replaceable class="parameter">increment</replaceable></ReturnValue>
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</TERM>
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<LISTITEM>
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<PARA>
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The <option>INCREMENT <replaceable class="parameter">increment</replaceable></option> clause is optional. A positive value will make an
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ascending sequence, a negative one a descending sequence. The default value
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is 1.
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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<VARLISTENTRY>
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<TERM>
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<ReturnValue><replaceable class="parameter">minvalue</replaceable></ReturnValue>
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</TERM>
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<LISTITEM>
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<PARA>
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The optional clause <option>MINVALUE
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<replaceable class="parameter">minvalue</replaceable></option>
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determines the minimum value
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a sequence can be. The defaults are 1 and -2147483647 for
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ascending and descending sequences, respectively.
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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<VARLISTENTRY>
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<TERM>
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<ReturnValue><replaceable class="parameter">maxvalue</replaceable></ReturnValue>
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</TERM>
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<LISTITEM>
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<PARA>
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|
Use the optional clause <option>MAXVALUE
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<replaceable class="parameter">maxvalue</replaceable></option> to
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determine the maximum
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value for the sequence. The defaults are 2147483647 and -1 for
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ascending and descending sequences, respectively.
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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<VARLISTENTRY>
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<TERM>
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<ReturnValue><replaceable class="parameter">start</replaceable></ReturnValue>
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</TERM>
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<LISTITEM>
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<PARA>
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|
The optional <option>START
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<replaceable class="parameter">start</replaceable>
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clause</option> enables the sequence to begin anywhere.
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The default starting value is
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<replaceable class="parameter">minvalue</replaceable>
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for ascending sequences and
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<replaceable class="parameter">maxvalue</replaceable>
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for descending ones.
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<comment>
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|
What happens if the user specifies start outside the range?
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|
</comment>
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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<VARLISTENTRY>
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<TERM>
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|
<ReturnValue><replaceable class="parameter">cache</replaceable></ReturnValue>
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|
</TERM>
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<LISTITEM>
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<PARA>
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|
|
The <option>CACHE <replaceable class="parameter">cache</replaceable></option> option
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|
|
enables sequence numbers to be preallocated
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|
|
and stored in memory for faster access. The minimum
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value is 1 (no cache) and this is also the default.
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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<VARLISTENTRY>
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<TERM>
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|
<ReturnValue>CYCLE</ReturnValue>
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|
|
</TERM>
|
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|
|
<LISTITEM>
|
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|
|
<PARA>
|
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|
|
The optional CYCLE keyword may be used to enable the sequence
|
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|
|
to continue when the
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|
<replaceable class="parameter">maxvalue</replaceable> or
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|
|
<replaceable class="parameter">minvalue</replaceable> has been
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|
|
reached by
|
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|
|
an ascending or descending sequence respectively. If the limit is
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|
|
reached, the next number generated will be whatever the
|
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|
|
<replaceable class="parameter">minvalue</replaceable> or
|
|
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|
|
<replaceable class="parameter">maxvalue</replaceable> is,
|
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|
|
as appropriate.
|
|
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|
|
</PARA>
|
|
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|
|
</LISTITEM>
|
|
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|
|
</VARLISTENTRY>
|
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|
|
</variablelist>
|
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|
|
</LISTITEM>
|
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|
|
</VARLISTENTRY>
|
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|
|
</variablelist>
|
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|
|
</REFSECT2>
|
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|
|
|
|
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|
|
<REFSECT2 ID="R2-SQL-CREATESEQUENCE-2">
|
|
|
|
|
<REFSECT2INFO>
|
|
|
|
|
<DATE>1998-04-15</DATE>
|
|
|
|
|
</REFSECT2INFO>
|
|
|
|
|
<TITLE>
|
|
|
|
|
Outputs
|
|
|
|
|
</TITLE>
|
|
|
|
|
<PARA>
|
|
|
|
|
</PARA>
|
|
|
|
|
<VARIABLELIST>
|
|
|
|
|
<VARLISTENTRY>
|
|
|
|
|
<TERM>
|
|
|
|
|
</TERM>
|
|
|
|
|
<LISTITEM>
|
|
|
|
|
<PARA>
|
|
|
|
|
<VARIABLELIST>
|
|
|
|
|
<VARLISTENTRY>
|
|
|
|
|
<TERM>
|
|
|
|
|
<ReturnValue>CREATE</ReturnValue>
|
|
|
|
|
</TERM>
|
|
|
|
|
<LISTITEM>
|
|
|
|
|
<PARA>
|
|
|
|
|
Message returned if the command is successful.
|
|
|
|
|
</PARA>
|
|
|
|
|
</LISTITEM>
|
|
|
|
|
</VARLISTENTRY>
|
|
|
|
|
<VARLISTENTRY>
|
|
|
|
|
<TERM>
|
|
|
|
|
<ReturnValue>ERROR: amcreate: '<replaceable class="parameter"> seqname</replaceable>' relation already exists</ReturnValue>
|
|
|
|
|
</TERM>
|
|
|
|
|
<LISTITEM>
|
|
|
|
|
<PARA>
|
|
|
|
|
If the sequence specified already exists.
|
|
|
|
|
</PARA>
|
|
|
|
|
</LISTITEM>
|
|
|
|
|
</VARLISTENTRY>
|
|
|
|
|
</variablelist>
|
|
|
|
|
</LISTITEM>
|
|
|
|
|
</VARLISTENTRY>
|
|
|
|
|
</VARIABLELIST>
|
|
|
|
|
</REFSECT2>
|
|
|
|
|
</REFSYNOPSISDIV>
|
|
|
|
|
|
|
|
|
|
<REFSECT1 ID="R1-SQL-CREATESEQUENCE-1">
|
|
|
|
|
<REFSECT1INFO>
|
|
|
|
|
<DATE>1998-04-15</DATE>
|
|
|
|
|
</REFSECT1INFO>
|
|
|
|
|
<TITLE>
|
|
|
|
|
Description
|
|
|
|
|
</TITLE>
|
|
|
|
|
<PARA>
|
|
|
|
|
CREATE SEQUENCE will enter a new sequence number generator
|
|
|
|
|
into the current data base. This involves creating and initialising a
|
|
|
|
|
new single block
|
|
|
|
|
table with the name <replaceable class="parameter">seqname</replaceable>.
|
|
|
|
|
The generator will be "owned" by the user issuing the command.
|
|
|
|
|
</PARA>
|
|
|
|
|
<para>
|
|
|
|
|
After the sequence is created, you may use the function
|
|
|
|
|
<function>nextval()</function> with the
|
|
|
|
|
sequence name as the argument to get a new number from the sequence.
|
|
|
|
|
The function <function>currval('<replaceable class="parameter">sequence_name</replaceable>')</function> may be used
|
|
|
|
|
to determine the number returned by the last call to
|
|
|
|
|
<function>nextval()</function> for the
|
|
|
|
|
specified sequence in the current session.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
Use a query like
|
|
|
|
|
<programlisting>
|
|
|
|
|
SELECT * FROM sequence_name;
|
|
|
|
|
</programlisting>
|
|
|
|
|
to get the parameters of a sequence.
|
|
|
|
|
</para>
|
|
|
|
|
<para>
|
|
|
|
|
Low-level locking is used to enable multiple simultaneous
|
|
|
|
|
calls to a generator.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<REFSECT2 ID="R2-SQL-CREATESEQUENCE-3">
|
|
|
|
|
<REFSECT2INFO>
|
|
|
|
|
<DATE>1998-04-15</DATE>
|
|
|
|
|
</REFSECT2INFO>
|
|
|
|
|
<TITLE>
|
|
|
|
|
Notes
|
|
|
|
|
</TITLE>
|
|
|
|
|
<PARA>
|
|
|
|
|
Refer to the DROP SEQUENCE statement to remove a sequence.
|
|
|
|
|
</PARA>
|
|
|
|
|
<para>
|
|
|
|
|
Each backend uses its own cache to store allocated numbers.
|
|
|
|
|
Numbers that are cached but not used in the current session will be
|
|
|
|
|
lost.
|
|
|
|
|
</para>
|
|
|
|
|
</REFSECT2>
|
|
|
|
|
</refsect1>
|
|
|
|
|
|
|
|
|
|
<REFSECT1 ID="R1-SQL-CREATESEQUENCE-2">
|
|
|
|
|
<TITLE>
|
|
|
|
|
Usage
|
|
|
|
|
</TITLE>
|
|
|
|
|
<PARA>
|
|
|
|
|
Create an ascending sequence called serial, starting at 101:
|
|
|
|
|
</PARA>
|
|
|
|
|
<ProgramListing>
|
|
|
|
|
CREATE SEQUENCE serial START 101;
|
|
|
|
|
</ProgramListing>
|
|
|
|
|
<para>
|
|
|
|
|
Select the next number from this sequence
|
|
|
|
|
<programlisting>
|
|
|
|
|
SELECT NEXTVAL ('serial');
|
|
|
|
|
|
|
|
|
|
nextval
|
|
|
|
|
-------
|
|
|
|
|
114
|
|
|
|
|
</programlisting>
|
|
|
|
|
</para>
|
|
|
|
|
<para>
|
|
|
|
|
Use this sequence in an INSERT:
|
|
|
|
|
<programlisting>
|
|
|
|
|
INSERT INTO distributors VALUES (NEXTVAL ('serial'),'nothing');
|
|
|
|
|
</programlisting>
|
|
|
|
|
</para>
|
|
|
|
|
</REFSECT1>
|
|
|
|
|
|
|
|
|
|
<REFSECT1 ID="R1-SQL-CREATESEQUENCE-3">
|
|
|
|
|
<TITLE>
|
|
|
|
|
Compatibility
|
|
|
|
|
</TITLE>
|
|
|
|
|
<PARA>
|
|
|
|
|
CREATE SEQUENCE statement is a PostgreSQL language extension.
|
|
|
|
|
</PARA>
|
|
|
|
|
|
|
|
|
|
<REFSECT2 ID="R2-SQL-CREATESEQUENCE-4">
|
|
|
|
|
<REFSECT2INFO>
|
|
|
|
|
<DATE>1998-04-15</DATE>
|
|
|
|
|
</REFSECT2INFO>
|
|
|
|
|
<TITLE>
|
|
|
|
|
SQL92
|
|
|
|
|
</TITLE>
|
|
|
|
|
<PARA>
|
|
|
|
|
There is no CREATE SEQUENCE statement on SQL92.
|
|
|
|
|
</PARA>
|
|
|
|
|
</refsect2>
|
|
|
|
|
</refsect1>
|
|
|
|
|
</REFENTRY>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<!-- Keep this comment at the end of the file
|
|
|
|
|
Local variables:
|
|
|
|
|
mode: sgml
|
|
|
|
|
sgml-omittag:t
|
|
|
|
|
sgml-shorttag:t
|
|
|
|
|
sgml-minimize-attributes:nil
|
|
|
|
|
sgml-always-quote-attributes:t
|
|
|
|
|
sgml-indent-step:1
|
|
|
|
|
sgml-indent-data:t
|
|
|
|
|
sgml-parent-document:nil
|
|
|
|
|
sgml-default-dtd-file:"../reference.ced"
|
|
|
|
|
sgml-exposed-tags:nil
|
|
|
|
|
sgml-local-catalogs:"/usr/lib/sgml/catalog"
|
|
|
|
|
sgml-local-ecat-files:nil
|
|
|
|
|
End:
|
|
|
|
|
-->
|
