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| <title>6. Query Factory</title><base href="display"><link rel="stylesheet" type="text/css" href="css/docbook.css"><meta name="generator" content="DocBook XSL-NS Stylesheets V1.76.1"><link rel="home" href="manual.html" title="Apache OpenJPA 2.2 User's Guide"><link rel="up" href="jpa_overview_em.html" title="Chapter 8. EntityManager"><link rel="prev" href="jpa_overview_em_cache.html" title="5. Cache Management"><link rel="next" href="jpa_overview_em_locking.html" title="7. Entity Locking"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">6. |
| Query Factory |
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| Query Factory |
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| <pre class="programlisting"> |
| public Query createQuery(String query); |
| </pre> |
| <p> |
| <code class="classname">Query</code> objects are used to find entities matching certain |
| criteria. The <code class="methodname">createQuery</code> method creates a query using |
| the given Java Persistence Query Language (JPQL) string. See |
| <a class="xref" href="jpa_overview_query.html" title="Chapter 10. JPA Query">Chapter 10, <i> |
| JPA Query |
| </i></a> for details. |
| </p> |
| <pre class="programlisting"> |
| public Query createNamedQuery(String name); |
| </pre> |
| <p> |
| This method retrieves a query defined in metadata by name. The returned |
| <code class="classname">Query</code> instance is initialized with the information |
| declared in metadata. For more information on named queries, read |
| <a class="xref" href="jpa_overview_query.html#jpa_overview_query_named" title="1.11. Named Queries">Section 1.11, “ |
| Named Queries |
| ”</a>. |
| </p> |
| <pre class="programlisting"> |
| public Query createNativeQuery(String sql); |
| public Query createNativeQuery(String sql, Class resultCls); |
| public Query createNativeQuery(String sql, String resultMapping); |
| </pre> |
| <p> |
| <span class="emphasis"><em>Native</em></span> queries are queries in the datastore's native |
| language. For relational databases, this is the Structured Query Language (SQL). |
| <a class="xref" href="jpa_overview_sqlquery.html" title="Chapter 12. SQL Queries">Chapter 12, <i> |
| SQL Queries |
| </i></a> elaborates on JPA's |
| native query support. |
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