session_api.pot

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

#, no-c-format
msgid "Queries that return tuples"
msgstr ""

#. Tag: para
#: session_api.xml:298
#, no-c-format
msgid "Hibernate queries sometimes return tuples of objects, in which case each tuple is returned as an array:"
msgstr ""

#. Tag: programlisting
#: session_api.xml:303
#, no-c-format
msgid ""
      "<![CDATA[Iterator kittensAndMothers = sess.createQuery(\n"
      "            \"select kitten, mother from Cat kitten join kitten.mother mother\")\n"
      "            .list()\n"
      "            .iterator();\n"
      "\n"
      "while ( kittensAndMothers.hasNext() ) {\n"
      "    Object[] tuple = (Object[]) kittensAndMothers.next();\n"
      "    Cat kitten = (Cat) tuple[0];\n"
      "    Cat mother = (Cat) tuple[1];\n"
      "    ....\n"
      "}]]>"
msgstr ""

#. Tag: title
#: session_api.xml:308
#, no-c-format
msgid "Scalar results"
msgstr ""

#. Tag: para
#: session_api.xml:310
#, no-c-format
msgid "Queries may specify a property of a class in the <literal>select</literal> clause. They may even call SQL aggregate functions. Properties or aggregates are considered \"scalar\" results (and not entities in persistent state)."
msgstr ""

#. Tag: programlisting
#: session_api.xml:316
#, no-c-format
msgid ""
      "<![CDATA[Iterator results = sess.createQuery(\n"
      "        \"select cat.color, min(cat.birthdate), count(cat) from Cat cat \" +\n"
      "        \"group by cat.color\")\n"
      "        .list()\n"
      "        .iterator();\n"
      "\n"
      "while ( results.hasNext() ) {\n"
      "    Object[] row = (Object[]) results.next();\n"
      "    Color type = (Color) row[0];\n"
      "    Date oldest = (Date) row[1];\n"
      "    Integer count = (Integer) row[2];\n"
      "    .....\n"
      "}]]>"
msgstr ""

#. Tag: title
#: session_api.xml:321
#, no-c-format
msgid "Bind parameters"
msgstr ""

#. Tag: para
#: session_api.xml:323
#, no-c-format
msgid "Methods on <literal>Query</literal> are provided for binding values to named parameters or JDBC-style <literal>?</literal> parameters. <emphasis>Contrary to JDBC, Hibernate numbers parameters from zero.</emphasis> Named parameters are identifiers of the form <literal>:name</literal> in the query string. The advantages of named parameters are:"
msgstr ""

#. Tag: para
#: session_api.xml:333
#, no-c-format
msgid "named parameters are insensitive to the order they occur in the query string"
msgstr ""

#. Tag: para
#: session_api.xml:339
#, no-c-format
msgid "they may occur multiple times in the same query"
msgstr ""

#. Tag: para
#: session_api.xml:344
#, no-c-format
msgid "they are self-documenting"
msgstr ""

#. Tag: programlisting
#: session_api.xml:350
#, no-c-format
msgid ""
      "<![CDATA[//named parameter (preferred)\n"
      "Query q = sess.createQuery(\"from DomesticCat cat where cat.name = :name\");\n"
      "q.setString(\"name\", \"Fritz\");\n"
      "Iterator cats = q.iterate();]]>"
msgstr ""

#. Tag: programlisting
#: session_api.xml:352
#, no-c-format
msgid ""
      "<![CDATA[//positional parameter\n"
      "Query q = sess.createQuery(\"from DomesticCat cat where cat.name = ?\");\n"
      "q.setString(0, \"Izi\");\n"
      "Iterator cats = q.iterate();]]>"
msgstr ""

#. Tag: programlisting
#: session_api.xml:354
#, no-c-format
msgid ""
      "<![CDATA[//named parameter list\n"
      "List names = new ArrayList();\n"
      "names.add(\"Izi\");\n"
      "names.add(\"Fritz\");\n"
      "Query q = sess.createQuery(\"from DomesticCat cat where cat.name in (:namesList)\");\n"
      "q.setParameterList(\"namesList\", names);\n"
      "List cats = q.list();]]>"
msgstr ""

#. Tag: title
#: session_api.xml:359
#, no-c-format
msgid "Pagination"
msgstr ""

#. Tag: para
#: session_api.xml:361
#, no-c-format
msgid "If you need to specify bounds upon your result set (the maximum number of rows you want to retrieve and / or the first row you want to retrieve) you should use methods of the <literal>Query</literal> interface:"
msgstr ""

#. Tag: programlisting
#: session_api.xml:367
#, no-c-format
msgid ""
      "<![CDATA[Query q = sess.createQuery(\"from DomesticCat cat\");\n"
      "q.setFirstResult(20);\n"
      "q.setMaxResults(10);\n"
      "List cats = q.list();]]>"
msgstr ""

#. Tag: para
#: session_api.xml:369
#, no-c-format
msgid "Hibernate knows how to translate this limit query into the native SQL of your DBMS."
msgstr ""

#. Tag: title
#: session_api.xml:377
#, no-c-format
msgid "Scrollable iteration"
msgstr ""

#. Tag: para
#: session_api.xml:379
#, no-c-format
msgid "If your JDBC driver supports scrollable <literal>ResultSet</literal>s, the <literal>Query</literal> interface may be used to obtain a <literal>ScrollableResults</literal> object, which allows flexible navigation of the query results."
msgstr ""

#. Tag: programlisting
#: session_api.xml:386
#, no-c-format
msgid ""
      "<![CDATA[Query q = sess.createQuery(\"select cat.name, cat from DomesticCat cat \" +\n"
      "                            \"order by cat.name\");\n"
      "ScrollableResults cats = q.scroll();\n"
      "if ( cats.first() ) {\n"
      "\n"
      "    // find the first name on each page of an alphabetical list of cats by name\n"
      "    firstNamesOfPages = new ArrayList();\n"
      "    do {\n"
      "        String name = cats.getString(0);\n"
      "        firstNamesOfPages.add(name);\n"
      "    }\n"
      "    while ( cats.scroll(PAGE_SIZE) );\n"
      "\n"
      "    // Now get the first page of cats\n"
      "    pageOfCats = new ArrayList();\n"
      "    cats.beforeFirst();\n"
      "    int i=0;\n"
      "    while( ( PAGE_SIZE > i++ ) && cats.next() ) pageOfCats.add( cats.get(1) );\n"
      "\n"
      "}\n"
      "cats.close()]]>"
msgstr ""

#. Tag: para
#: session_api.xml:388
#, no-c-format
msgid "Note that an open database connection (and cursor) is required for this functionality, use <literal>setMaxResult()</literal>/<literal>setFirstResult()</literal> if you need offline pagination functionality."
msgstr ""

#. Tag: title
#: session_api.xml:397
#, no-c-format
msgid "Externalizing named queries"
msgstr ""

#. Tag: para
#: session_api.xml:399
#, no-c-format
msgid "You may also define named queries in the mapping document. (Remember to use a <literal>CDATA</literal> section if your query contains characters that could be interpreted as markup.)"
msgstr ""

#. Tag: programlisting
#: session_api.xml:405
#, no-c-format
msgid ""
      "<![CDATA[<query name=\"ByNameAndMaximumWeight\"><![CDATA[\n"
      "    from eg.DomesticCat as cat\n"
      "        where cat.name = ?\n"
      "        and cat.weight > ?\n"
      "] ]></query>]]>"
msgstr ""

#. Tag: para
#: session_api.xml:407
#, no-c-format
msgid "Parameter binding and executing is done programatically:"
msgstr ""

#. Tag: programlisting
#: session_api.xml:411
#, no-c-format
msgid ""
      "<![CDATA[Query q = sess.getNamedQuery(\"ByNameAndMaximumWeight\");\n"
      "q.setString(0, name);\n"
      "q.setInt(1, minWeight);\n"
      "List cats = q.list();]]>"
msgstr ""

#. Tag: para
#: session_api.xml:413
#, no-c-format
msgid "Note that the actual program code is independent of the query language that is used, you may also define native SQL queries in metadata, or migrate existing queries to Hibernate by placing them in mapping files."
msgstr ""

#. Tag: para
#: session_api.xml:419
#, no-c-format
msgid "Also note that a query declaration inside a <literal>&lt;hibernate-mapping&gt;</literal> element requires a global unique name for the query, while a query declaration inside a <literal>&lt;class&gt;</literal> element is made unique automatically by prepending the fully qualified name of the class, for example <literal>eg.Cat.ByNameAndMaximumWeight</literal>."
msgstr ""

#. Tag: title
#: session_api.xml:432
#, no-c-format
msgid "Filtering collections"
msgstr ""

#. Tag: para
#: session_api.xml:433
#, no-c-format
msgid "A collection <emphasis>filter</emphasis> is a special type of query that may be applied to a persistent collection or array. The query string may refer to <literal>this</literal>, meaning the current collection element."
msgstr ""

#. Tag: programlisting
#: session_api.xml:439
#, no-c-format
msgid ""
      "<![CDATA[Collection blackKittens = session.createFilter(\n"
      "    pk.getKittens(), \n"
      "    \"where this.color = ?\")\n"
      "    .setParameter( Color.BLACK, Hibernate.custom(ColorUserType.class) )\n"
      "    .list()\n"
      ");]]>"
msgstr ""

#. Tag: para
#: session_api.xml:441
#, no-c-format
msgid "The returned collection is considered a bag, and it's a copy of the given collection. The original collection is not modified (this is contrary to the implication of the name \"filter\", but consistent with expected behavior)."
msgstr ""

#. Tag: para
#: session_api.xml:447
#, no-c-format
msgid "Observe that filters do not require a <literal>from</literal> clause (though they may have one if required). Filters are not limited to returning the collection elements themselves."
msgstr ""

#. Tag: programlisting
#: session_api.xml:452
#, no-c-format
msgid ""
      "<![CDATA[Collection blackKittenMates = session.createFilter(\n"
      "    pk.getKittens(), \n"
      "    \"select this.mate where this.color = eg.Color.BLACK.intValue\")\n"
      "    .list();]]>"
msgstr ""

#. Tag: para
#: session_api.xml:454
#, no-c-format
msgid "Even an empty filter query is useful, e.g. to load a subset of elements in a huge collection:"
msgstr ""

#. Tag: programlisting
#: session_api.xml:459
#, no-c-format
msgid ""
      "<![CDATA[Collection tenKittens = session.createFilter(\n"
      "    mother.getKittens(), \"\")\n"
      "    .setFirstResult(0).setMaxResults(10)\n"
      "    .list();]]>"
msgstr ""

#. Tag: title
#: session_api.xml:464
#, no-c-format
msgid "Criteria queries"
msgstr ""

#. Tag: para
#: session_api.xml:466
#, no-c-format
msgid "HQL is extremely powerful but some developers prefer to build queries dynamically, using an object-oriented API, rather than building query strings. Hibernate provides an intuitive <literal>Criteria</literal> query API for these cases:"
msgstr ""

#. Tag: programlisting
#: session_api.xml:472
#, no-c-format
msgid ""
      "<![CDATA[Criteria crit = session.createCriteria(Cat.class);\n"
      "crit.add( Restrictions.eq( \"color\", eg.Color.BLACK ) );\n"
      "crit.setMaxResults(10);\n"
      "List cats = crit.list();]]>"
msgstr ""

#. Tag: para
#: session_api.xml:474
#, no-c-format
msgid "The <literal>Criteria</literal> and the associated <literal>Example</literal> API are discussed in more detail in <xref linkend=\"querycriteria\"/>."
msgstr ""

#. Tag: title
#: session_api.xml:482
#, no-c-format
msgid "Queries in native SQL"