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    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <concept id="GUID-13C95985-D16F-5A9E-A7F8-CAB637C4C6ED" xml:lang="en"><title>DBMS

    13 Overview</title><shortdesc>Provides an interface to relational databases. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 <section id="GUID-40E204A0-AAE5-46AA-BC88-2A80D81AC710"><title>Purpose</title> <p id="GUID-844F756E-1670-5D24-8D63-2092ABE3354C"> The

    15 DBMS component provides an interface to relational databases. It enables you

    16 to create and access databases either from a single client or from multiple

    17 clients sharing access over a server. </p> </section>

    18 <section id="GUID-AC97ABD1-CD17-403B-B654-91A75A6C627A"><title>Required background</title> <p>To use DBMS you need a knowledge

    19 of relational databases and the SQL query language. </p> </section>

    20 <section id="GUID-B0F498B6-722A-4FE2-B7B2-5064FEFF9470"><title>Key concepts and terms</title> <dl>

    21 <dlentry>

    22 <dt>Store database </dt>

    23 <dd><p>A client-side single client database stored in permanent file stores,

    24 implemented by <xref href="GUID-F4A68645-2265-307F-B951-8295827E000B.dita"><apiname>RDbStoreDatabase</apiname></xref>  </p> </dd>

    25 </dlentry>

    26 <dlentry>

    27 <dt>Named database </dt>

    28 <dd><p>A database allowing simultaneous read/write access by multiple clients,

    29 implemented by <xref href="GUID-6433D7F9-B4C7-39DA-BEF4-5EA22B8478A2.dita"><apiname>RDbNamedDatabase</apiname></xref>  </p> </dd>

    30 </dlentry>

    31 </dl> </section>

    32 <section id="GUID-856FC618-CF46-4735-B90B-B1BDB91F01D5"><title>Architecture</title> <p>DBMS defines a general relational

    33 database access API, and allows different database implementations to be provided

    34 of which there are two: a small and relatively lightweight client-side implementation;

    35 and, for when multiple clients must have write access to a database, a client-server

    36 implementation. </p> <p>When multiple clients can access the same database,

    37 transactions ensure that only one client can change data at a time. </p> <p>The <xref href="GUID-21CF1D5F-44C5-5407-B3C9-8BC103C97079.dita">File Stores</xref> API defines

    38 a sophisticated file storage, called permanent file stores, that allows individual

    39 entries in a file to be modified. The database implementations use these stores

    40 for the underlying data storage. </p> <fig id="GUID-6907C48E-3E72-5FED-B5E5-67C6F6922ED9">

    41 <title>              DBMS Class Diagrams           </title>

    42 <image href="GUID-6A482ACB-D39E-578B-B58B-44E4142A5897_d0e357898_href.png" placement="inline"/>

    43 </fig> </section>

    44 <section id="GUID-CC1087EA-0995-4ABE-8C28-8CBF0D62E7FA"><title>DBMS Summary</title> <p>DBMS provides the following: </p> <ul>

    45 <li id="GUID-CA46F9A6-15C2-5584-A907-9D1DD79C8711"><p> <b>Database Management

    46 System Library</b>  </p> <p> <filepath>edbms.dll</filepath>  </p> </li>

    47 <li id="GUID-8D01F878-BCA7-5F88-AC31-BEA68B0739CD"><p> <b>Database Management

    48 System Server</b>  </p> <p> <filepath>edbsrv.exe</filepath>  </p> </li>

    49 </ul> </section>

    50 <section id="GUID-8534CB50-0E49-4614-883B-61B6B583ABCB"><title>APIs</title> <table id="GUID-E682487D-23AC-5A0A-89F5-568D73452AF1">

    51 <tgroup cols="2"><colspec colname="col0"/><colspec colname="col1"/>

    52 <thead>

    53 <row>

    54 <entry>API</entry>

    55 <entry>Description</entry>

    56 </row>

    57 </thead>

    58 <tbody>

    59 <row>

    60 <entry><p> <xref href="GUID-E11B1981-CA78-3660-AE09-AD3B4D453733.dita"><apiname>RDbDatabase</apiname></xref>  </p> </entry>

    61 <entry><p>Abstract database class. </p> </entry>

    62 </row>

    63 <row>

    64 <entry><p> <xref href="GUID-F4A68645-2265-307F-B951-8295827E000B.dita"><apiname>RDbStoreDatabase</apiname></xref>  </p> </entry>

    65 <entry><p>Implements <codeph>RDbDatabase</codeph> as a store database. </p> </entry>

    66 </row>

    67 <row>

    68 <entry><p> <xref href="GUID-6433D7F9-B4C7-39DA-BEF4-5EA22B8478A2.dita"><apiname>RDbNamedDatabase</apiname></xref>  </p> </entry>

    69 <entry><p>Implements a named database. </p> </entry>

    70 </row>

    71 <row>

    72 <entry><p> <xref href="GUID-F861EB8F-F621-3E77-8F9A-5E4EFC4E9C2F.dita"><apiname>RDbRowSet</apiname></xref>  </p> </entry>

    73 <entry><p>The base class for all rowset types. </p> </entry>

    74 </row>

    75 <row>

    76 <entry><p> <xref href="GUID-90ABFA73-6374-367C-BAA9-88CD810035CC.dita"><apiname>RDbTable</apiname></xref>  </p> </entry>

    77 <entry><p>Provides access to table data as a rowset. </p> </entry>

    78 </row>

    79 <row>

    80 <entry><p> <xref href="GUID-AE1BEF00-5AA7-3F03-95B0-9E40395EDA6C.dita"><apiname>RDbView</apiname></xref>  </p> </entry>

    81 <entry><p>Generates rowsets from an SQL query. </p> </entry>

    82 </row>

    83 <row>

    84 <entry><p> <xref href="GUID-A7C9FEFA-A9A9-357F-AF66-FA3A288AF925.dita"><apiname>TDbQuery</apiname></xref>  </p> </entry>

    85 <entry><p>A wrapper for an SQL string combined with a text comparison mode. </p> </entry>

    86 </row>

    87 <row>

    88 <entry><p> <xref href="GUID-E53A90DF-3589-34BD-B7C3-02371567AF41.dita"><apiname>TDbWindow</apiname></xref>  </p> </entry>

    89 <entry><p>Describes the desired shape of a view's pre-evaluation window. </p> </entry>

    90 </row>

    91 <row>

    92 <entry><p> <xref href="GUID-53AB4535-A859-3A8C-8344-53865B2FE0B4.dita"><apiname>RDbNotifier</apiname></xref>  </p> </entry>

    93 <entry><p>Provides notification of database changes to clients. </p> </entry>

    94 </row>

    95 </tbody>

    96 </tgroup>

    97 </table> </section>

    98 <section id="GUID-B73210AC-8B93-430A-8E6F-8FD06C631E90"><title>Typical uses</title> <p>DBMS is very well suited to applications

    99 with small to medium-sized datasets, where the total record count is less

   100 than 10,000 and the database size is less than 512KB. It scales reasonably

   101 well to larger datasets with total record counts less than 100,000 and database

   102 sizes less than 10MB. </p> <p>DBMS is a suitable database engine for applications

   103 such as: </p> <ul>

   104 <li id="GUID-3638AC16-C761-5FEE-BFE1-C516C5674C88"><p>address books </p> </li>

   105 <li id="GUID-7C3E01B0-898A-5FC0-9C48-EB7D998C878D"><p>call logs </p> </li>

   106 <li id="GUID-B8F92167-446A-5CB0-A5A6-998B2E1ED9A4"><p>message stores. </p> </li>

   107 </ul> </section>

   108 </conbody><related-links>

   109 <link href="GUID-F4875493-6501-56FC-90E5-5EEAA89A72C3.dita"><linktext>Persistent

   110 Storage Overview</linktext></link>

   111 <link href="GUID-12CB6E0E-69CD-51A6-8966-3621CB26E1CD.dita"><linktext>DBMS

   112 rowsets overview</linktext></link>

   113 <link href="GUID-7BE83158-B818-57E4-9A8C-43E5D2C84687.dita"><linktext>DBMS columns,

   114 column sets, and                 keys overview</linktext></link>

   115 <link href="GUID-C61B979A-921A-5756-8D7E-691C3DDD3437.dita"><linktext>DBMS sharing

   116 databases                 overview</linktext></link>

   117 <link href="GUID-120163D6-2E49-5D91-A746-2C8C4C944461.dita"><linktext>DBMS incremental

   118 operations                 overview</linktext></link>

   119 <link href="GUID-21CF1D5F-44C5-5407-B3C9-8BC103C97079.dita"><linktext>File stores

   120 overview</linktext></link>

   121 </related-links></concept>