current_date.sgml

关系型数据库 Postgresql 6.5.2

<REFENTRY ID="SQL-CURRENT-DATE">
 <REFMETA>
  <REFENTRYTITLE>
   SQL_CURRENT_DATE
  </REFENTRYTITLE>
  <REFMISCINFO>SQL - Functions</REFMISCINFO>
 </REFMETA>
 <REFNAMEDIV>
  <REFNAME>
   CURRENT_DATE
  </REFNAME>
  <REFPURPOSE>
Returns the current date
  </REFPURPOSE>
 <REFSYNOPSISDIV>
  <REFSYNOPSISDIVINFO>
   <DATE>1998-04-15</DATE>
  </REFSYNOPSISDIVINFO>
  <SYNOPSIS>
   CURRENT_DATE
  </SYNOPSIS>
  
  <REFSECT2 ID="R2-SQL-CURRENT-DATE-1">
   <REFSECT2INFO>
    <DATE>1998-04-15</DATE>
   </REFSECT2INFO>
   <TITLE>
    Inputs
   </TITLE>
   <PARA>
None.
  </REFSECT2>
  
  <REFSECT2 ID="R2-SQL-CURRENT-DATE-2">
   <REFSECT2INFO>
    <DATE>1998-04-15</DATE>
   </REFSECT2INFO>
   <TITLE>
    Outputs
   </TITLE>
   <PARA>
       <VARIABLELIST>
	<VARLISTENTRY>
	 <TERM>
<replaceable>date</replaceable>

	 </TERM>
	 <LISTITEM>
	  <PARA>
	  Returns "<replaceable class="parameter">today</replaceable>".
   </VARIABLELIST>
  </REFSECT2>
 </REFSYNOPSISDIV>
 
 <REFSECT1 ID="R1-SQL-CURRENT-DATE-1">
  <REFSECT1INFO>
   <DATE>1998-04-15</DATE>
  </REFSECT1INFO>
  <TITLE>
   Description
  </TITLE>
  <PARA>
   The niladic CURRENT_DATE function has a data type of
   DATE and returns the date at the time that it is run.
  </PARA>
  
  <REFSECT2 ID="R2-SQL-CURRENT-DATE-3">
   <REFSECT2INFO>
    <DATE>1998-04-15</DATE>
   </REFSECT2INFO>
   <TITLE>
    Notes
   </TITLE>
   <PARA>
    Refer to SET DATESTYLE for further information about date format.
   </PARA>
  </REFSECT2>
  
 <REFSECT1 ID="R1-SQL-CURRENT-DATE-2">
  <TITLE>
   Usage
  </TITLE>
  <PARA>
   Insert the date of insertion into a row:
  </PARA>
  <ProgramListing>
   INSERT INTO films
         VALUES ('TM999','Ben Hur',105,CURRENT_DATE,'Action',NULL);
  </ProgramListing>
  
  <PARA>
   Display CURRENT-DATE:
  </PARA>
  <ProgramListing>
   SELECT CURRENT_DATE AS today;

   today
   ------------
   1998-03-31

  </ProgramListing>
 </REFSECT1>
 
 <REFSECT1 ID="R1-SQL-CURRENT-DATE-3">
  <TITLE>
   Compatibility
  </TITLE>
  <PARA>
  </PARA>
  
  <REFSECT2 ID="R2-SQL-CURRENT-DATE-4">
   <REFSECT2INFO>
    <DATE>1998-04-15</DATE>
   </REFSECT2INFO>
   <TITLE>
    SQL92
   </TITLE>
   <PARA>
    Full compatibility.
   </PARA>
  </refsect2>
 </refsect1>
</REFENTRY>

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