query_hql.pot

hibernate-distribution-3.3.1.GA-dist.zip源码

msgstr ""

#. Tag: programlisting
#: query_hql.xml:317
#, no-c-format
msgid ""
      "<![CDATA[select max(bodyWeight) as max, min(bodyWeight) as min, count(*) as n\n"
      "from Cat cat]]>"
msgstr ""

#. Tag: para
#: query_hql.xml:319
#, no-c-format
msgid "This is most useful when used together with <literal>select new map</literal>:"
msgstr ""

#. Tag: programlisting
#: query_hql.xml:323
#, no-c-format
msgid ""
      "<![CDATA[select new map( max(bodyWeight) as max, min(bodyWeight) as min, count(*) as n )\n"
      "from Cat cat]]>"
msgstr ""

#. Tag: para
#: query_hql.xml:325
#, no-c-format
msgid "This query returns a <literal>Map</literal> from aliases to selected values."
msgstr ""

#. Tag: title
#: query_hql.xml:332
#, no-c-format
msgid "Aggregate functions"
msgstr ""

#. Tag: para
#: query_hql.xml:334
#, no-c-format
msgid "HQL queries may even return the results of aggregate functions on properties:"
msgstr ""

#. Tag: programlisting
#: query_hql.xml:338
#, no-c-format
msgid ""
      "<![CDATA[select avg(cat.weight), sum(cat.weight), max(cat.weight), count(cat)\n"
      "from Cat cat]]>"
msgstr ""

#. Tag: para
#: query_hql.xml:349
#, no-c-format
msgid "The supported aggregate functions are"
msgstr ""

#. Tag: literal
#: query_hql.xml:356
#, no-c-format
msgid "avg(...), sum(...), min(...), max(...)"
msgstr ""

#. Tag: literal
#: query_hql.xml:361
#, no-c-format
msgid "count(*)"
msgstr ""

#. Tag: literal
#: query_hql.xml:366
#, no-c-format
msgid "count(...), count(distinct ...), count(all...)"
msgstr ""

#. Tag: para
#: query_hql.xml:371
#, no-c-format
msgid "You may use arithmetic operators, concatenation, and recognized SQL functions in the select clause:"
msgstr ""

#. Tag: programlisting
#: query_hql.xml:376
#, no-c-format
msgid ""
      "<![CDATA[select cat.weight + sum(kitten.weight)\n"
      "from Cat cat\n"
      "    join cat.kittens kitten\n"
      "group by cat.id, cat.weight]]>"
msgstr ""

#. Tag: programlisting
#: query_hql.xml:378
#, no-c-format
msgid "<![CDATA[select firstName||' '||initial||' '||upper(lastName) from Person]]>"
msgstr ""

#. Tag: para
#: query_hql.xml:380
#, no-c-format
msgid "The <literal>distinct</literal> and <literal>all</literal> keywords may be used and have the same semantics as in SQL."
msgstr ""

#. Tag: programlisting
#: query_hql.xml:385
#, no-c-format
msgid ""
      "<![CDATA[select distinct cat.name from Cat cat\n"
      "\n"
      "select count(distinct cat.name), count(cat) from Cat cat]]>"
msgstr ""

#. Tag: title
#: query_hql.xml:390
#, no-c-format
msgid "Polymorphic queries"
msgstr ""

#. Tag: para
#: query_hql.xml:392
#, no-c-format
msgid "A query like:"
msgstr ""

#. Tag: para
#: query_hql.xml:398
#, no-c-format
msgid "returns instances not only of <literal>Cat</literal>, but also of subclasses like <literal>DomesticCat</literal>. Hibernate queries may name <emphasis>any</emphasis> Java class or interface in the <literal>from</literal> clause. The query will return instances of all persistent classes that extend that class or implement the interface. The following query would return all persistent objects:"
msgstr ""

#. Tag: programlisting
#: query_hql.xml:406
#, no-c-format
msgid "<![CDATA[from java.lang.Object o]]>"
msgstr ""

#. Tag: para
#: query_hql.xml:408
#, no-c-format
msgid "The interface <literal>Named</literal> might be implemented by various persistent classes:"
msgstr ""

#. Tag: programlisting
#: query_hql.xml:413
#, no-c-format
msgid "<![CDATA[from Named n, Named m where n.name = m.name]]>"
msgstr ""

#. Tag: para
#: query_hql.xml:415
#, no-c-format
msgid "Note that these last two queries will require more than one SQL <literal>SELECT</literal>. This means that the <literal>order by</literal> clause does not correctly order the whole result set. (It also means you can't call these queries using <literal>Query.scroll()</literal>.)"
msgstr ""

#. Tag: title
#: query_hql.xml:424
#, no-c-format
msgid "The where clause"
msgstr ""

#. Tag: para
#: query_hql.xml:426
#, no-c-format
msgid "The <literal>where</literal> clause allows you to narrow the list of instances returned. If no alias exists, you may refer to properties by name:"
msgstr ""

#. Tag: programlisting
#: query_hql.xml:431
#, no-c-format
msgid "<![CDATA[from Cat where name='Fritz']]>"
msgstr ""

#. Tag: para
#: query_hql.xml:433
#, no-c-format
msgid "If there is an alias, use a qualified property name:"
msgstr ""

#. Tag: programlisting
#: query_hql.xml:437
#, no-c-format
msgid "<![CDATA[from Cat as cat where cat.name='Fritz']]>"
msgstr ""

#. Tag: para
#: query_hql.xml:439
#, no-c-format
msgid "returns instances of <literal>Cat</literal> named 'Fritz'."
msgstr ""

#. Tag: programlisting
#: query_hql.xml:443
#, no-c-format
msgid ""
      "<![CDATA[select foo\n"
      "from Foo foo, Bar bar\n"
      "where foo.startDate = bar.date]]>"
msgstr ""

#. Tag: para
#: query_hql.xml:445
#, no-c-format
msgid "will return all instances of <literal>Foo</literal> for which there exists an instance of <literal>bar</literal> with a <literal>date</literal> property equal to the <literal>startDate</literal> property of the <literal>Foo</literal>. Compound path expressions make the <literal>where</literal> clause extremely powerful. Consider:"
msgstr ""

#. Tag: programlisting
#: query_hql.xml:454
#, no-c-format
msgid "<![CDATA[from Cat cat where cat.mate.name is not null]]>"
msgstr ""

#. Tag: para
#: query_hql.xml:456
#, no-c-format
msgid "This query translates to an SQL query with a table (inner) join. If you were to write something like"
msgstr ""

#. Tag: programlisting
#: query_hql.xml:461
#, no-c-format
msgid ""
      "<![CDATA[from Foo foo\n"
      "where foo.bar.baz.customer.address.city is not null]]>"
msgstr ""

#. Tag: para
#: query_hql.xml:463
#, no-c-format
msgid "you would end up with a query that would require four table joins in SQL."
msgstr ""

#. Tag: para
#: query_hql.xml:467
#, no-c-format
msgid "The <literal>=</literal> operator may be used to compare not only properties, but also instances:"
msgstr ""

#. Tag: programlisting
#: query_hql.xml:472
#, no-c-format
msgid "<![CDATA[from Cat cat, Cat rival where cat.mate = rival.mate]]>"
msgstr ""

#. Tag: programlisting
#: query_hql.xml:474
#, no-c-format
msgid ""
      "<![CDATA[select cat, mate\n"
      "from Cat cat, Cat mate\n"
      "where cat.mate = mate]]>"
msgstr ""

#. Tag: para
#: query_hql.xml:476
#, no-c-format
msgid "The special property (lowercase) <literal>id</literal> may be used to reference the unique identifier of an object. See <xref linkend=\"queryhql-identifier-property\"/> for more information."
msgstr ""

#. Tag: programlisting
#: query_hql.xml:482
#, no-c-format
msgid ""
      "<![CDATA[from Cat as cat where cat.id = 123\n"
      "\n"
      "from Cat as cat where cat.mate.id = 69]]>"
msgstr ""

#. Tag: para
#: query_hql.xml:484
#, no-c-format
msgid "The second query is efficient. No table join is required!"
msgstr ""

#. Tag: para
#: query_hql.xml:488
#, no-c-format
msgid "Properties of composite identifiers may also be used. Suppose <literal>Person</literal> has a composite identifier consisting of <literal>country</literal> and <literal>medicareNumber</literal>. Again, see <xref linkend=\"queryhql-identifier-property\"/> for more information regarding referencing identifier properties."
msgstr ""

#. Tag: programlisting
#: query_hql.xml:495
#, no-c-format
msgid ""
      "<![CDATA[from bank.Person person\n"
      "where person.id.country = 'AU'\n"
      "    and person.id.medicareNumber = 123456]]>"
msgstr ""

#. Tag: programlisting
#: query_hql.xml:497
#, no-c-format
msgid ""
      "<![CDATA[from bank.Account account\n"
      "where account.owner.id.country = 'AU'\n"
      "    and account.owner.id.medicareNumber = 123456]]>"
msgstr ""

#. Tag: para
#: query_hql.xml:499
#, no-c-format
msgid "Once again, the second query requires no table join."
msgstr ""

#. Tag: para
#: query_hql.xml:503
#, no-c-format
msgid "Likewise, the special property <literal>class</literal> accesses the discriminator value of an instance in the case of polymorphic persistence. A Java class name embedded in the where clause will be translated to its discriminator value."
msgstr ""

#. Tag: programlisting
#: query_hql.xml:509
#, no-c-format
msgid "<![CDATA[from Cat cat where cat.class = DomesticCat]]>"
msgstr ""

#. Tag: para
#: query_hql.xml:511
#, no-c-format
msgid "You may also use components or composite user types, or properties of said component types. See <xref linkend=\"queryhql-components\"/> for more details."
msgstr ""

#. Tag: para
#: query_hql.xml:516
#, no-c-format
msgid "An \"any\" type has the special properties <literal>id</literal> and <literal>class</literal>, allowing us to express a join in the following way (where <literal>AuditLog.item</literal> is a property mapped with <literal>&lt;any&gt;</literal>)."
msgstr ""

#. Tag: programlisting
#: query_hql.xml:522
#, no-c-format
msgid ""
      "<![CDATA[from AuditLog log, Payment payment\n"
      "where log.item.class = 'Payment' and log.item.id = payment.id]]>"
msgstr ""

#. Tag: para
#: query_hql.xml:524
#, no-c-format
msgid "Notice that <literal>log.item.class</literal> and <literal>payment.class</literal> would refer to the values of completely different database columns in the above query."
msgstr ""

#. Tag: title
#: query_hql.xml:532
#, no-c-format
msgid "Expressions"
msgstr ""

#. Tag: para
#: query_hql.xml:534
#, no-c-format
msgid "Expressions allowed in the <literal>where</literal> clause include most of the kind of things you could write in SQL:"
msgstr ""

#. Tag: para
#: query_hql.xml:541
#, no-c-format
msgid "mathematical operators <literal>+, -, *, /</literal>"
msgstr ""

#. Tag: para
#: query_hql.xml:546
#, no-c-format
msgid "binary comparison operators <literal>=, &gt;=, &lt;=, &lt;&gt;, !=, like</literal>"
msgstr ""

#. Tag: para
#: query_hql.xml:551
#, no-c-format
msgid "logical operations <literal>and, or, not</literal>"
msgstr ""

#. Tag: para
#: query_hql.xml:556
#, no-c-format
msgid "Parentheses <literal>( )</literal>, indicating grouping"
msgstr ""

#. Tag: para
#: query_hql.xml:561
#, no-c-format
msgid "<literal>in</literal>, <literal>not in</literal>, <literal>between</literal>, <literal>is null</literal>, <literal>is not null</literal>, <literal>is empty</literal>, <literal>is not empty</literal>, <literal>member of</literal> and <literal>not member of</literal>"
msgstr ""

#. Tag: para
#: query_hql.xml:574
#, no-c-format
msgid "\"Simple\" case, <literal>case ... when ... then ... else ... end</literal>, and \"searched\" case, <literal>case when ... then ... else ... end</literal>"
msgstr ""

#. Tag: para
#: query_hql.xml:580
#, no-c-format
msgid "string concatenation <literal>...||...</literal> or <literal>concat(...,...)</literal>"
msgstr ""

#. Tag: para
#: query_hql.xml:585
#, no-c-format
msgid "<literal>current_date()</literal>, <literal>current_time()</literal>, <literal>current_timestamp()</literal>"
msgstr ""

#. Tag: para
#: query_hql.xml:591
#, no-c-format
msgid "<literal>second(...)</literal>, <literal>minute(...)</literal>, <literal>hour(...)</literal>, <literal>day(...)</literal>, <literal>month(...)</literal>, <literal>year(...)</literal>,"
msgstr ""

#. Tag: para
#: query_hql.xml:598
#, no-c-format
msgid "Any function or operator defined by EJB-QL 3.0: <literal>substring(), trim(), lower(), upper(), length(), locate(), abs(), sqrt(), bit_length(), mod()</literal>"
msgstr ""

#. Tag: para
#: query_hql.xml:604
#, no-c-format
msgid "<literal>coalesce()</literal> and <literal>nullif()</literal>"
msgstr ""

#. Tag: para
#: query_hql.xml:609
#, no-c-format
msgid "<literal>str()</literal> for converting numeric or temporal values to a readable string"
msgstr ""

#. Tag: para
#: query_hql.xml:615
#, no-c-format
msgid "<literal>cast(... as ...)</literal>, where the second argument is the name of a Hibernate type, and <literal>extract(... from ...)</literal> if ANSI <literal>cast()</literal> and <literal>extract()</literal> is supported by the underlying database"
msgstr ""

#. Tag: para
#: query_hql.xml:623
#, no-c-format
msgid "the HQL <literal>index()</literal> function, that applies to aliases of a joined indexed collection"
msgstr ""

#. Tag: para
#: query_hql.xml:629
#, no-c-format
msgid "HQL functions that take collection-valued path expressions: <literal>size(), minelement(), maxelement(), minindex(), maxindex()</literal>, along with the special <literal>elements()</literal> and <literal>indices</literal> functions which may be quantified using <literal>some, all, exists, any, in</literal>."
msgstr ""

#. Tag: para
#: query_hql.xml:637
#, no-c-format
msgid "Any database-supported SQL scalar function like <literal>sign()</literal>, <literal>trunc()</literal>, <literal>rtrim()</literal>, <literal>sin()</literal>"
msgstr ""

#. Tag: para