12 <concept xml:lang="en" id="GUID-12CB6E0E-69CD-51A6-8966-3621CB26E1CD"><title>DBMS rowsets overview</title><prolog><metadata><keywords/></metadata></prolog><conbody><section><title>Purpose</title> <p>Allows data contained in a database to be retrieved, searched, and modified.</p> </section> <section><title>Description</title> <p>The API has three key concepts: rowset base, table rowset, and SQL view. </p> <p><b>Rowset base</b> </p> <p>Rowsets provide the following:</p> <ul><li id="GUID-5EC6A9C9-2C0F-5141-A600-815C61FA5DC8"><p>retrieving data from a database</p> </li> <li id="GUID-145F724B-4AFF-5987-9DC1-C94D5FE9C54C"><p>navigating the rowset with a cursor</p> </li> <li id="GUID-BD487F4B-D14F-5575-95BB-2A1A5ECBC020"><p>row finding and matching </p> </li> <li id="GUID-56F7E17F-3009-5E2C-A015-CF09D03C98F1"><p>updating or inserting rows</p> </li> <li id="GUID-FE9D6B32-74CE-54C7-8DBB-C7578673282F"><p>getting the schema of the rows within the rowset</p> </li> <li id="GUID-FA52E8CD-8943-560F-8613-BF7D0E6A05A8"><p>extracting and setting columns in a row</p> </li> </ul> <p>A base class is defined for all rowset types by <xref href="GUID-F861EB8F-F621-3E77-8F9A-5E4EFC4E9C2F.dita"><apiname>RDbRowSet</apiname></xref>. Concrete types of rowset derive from this.</p> <p><b>Table rowset</b> </p> <p>This provides all the rows and columns of a table as a rowset. Indexes can be used to order the rowset, and to provide fast key-based row retrieval from the table. It is encapsulated in <xref href="GUID-90ABFA73-6374-367C-BAA9-88CD810035CC.dita"><apiname>RDbTable</apiname></xref>. </p> <p><b>SQL view</b> </p> <p>This provides a rowset based on an SQL query. It is provided by <xref href="GUID-AE1BEF00-5AA7-3F03-95B0-9E40395EDA6C.dita"><apiname>RDbView</apiname></xref>. An SQL query is encapsulated in <xref href="GUID-A7C9FEFA-A9A9-357F-AF66-FA3A288AF925.dita"><apiname>TDbQuery</apiname></xref>.</p> <p>For large rowsets, it can be useful to define the balance between memory usage (greatest if the view stores the complete rowset) and speed (slowest if the rowset is evaluated for each cursor navigation). This is called the pre-evaluation window, and is provided by <xref href="GUID-E53A90DF-3589-34BD-B7C3-02371567AF41.dita"><apiname>TDbWindow</apiname></xref>.</p> </section> </conbody></concept>

    12 <concept id="GUID-12CB6E0E-69CD-51A6-8966-3621CB26E1CD" xml:lang="en"><title>DBMS

    13 rowsets overview</title><shortdesc>DBMS rowsets allow data contained in a database to be retrieved,

    14 searched, and modified.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    15 <section id="GUID-33E7933A-C5A2-4159-8858-422C60E57BDA"><title>Description</title> <p>The API has three key concepts: rowset

    16 base, table rowset, and SQL view. </p> <p><b>Rowset

    17 base</b> </p> <p>Rowsets provide the following:</p> <ul>

    18 <li id="GUID-5EC6A9C9-2C0F-5141-A600-815C61FA5DC8"><p>retrieving data from

    19 a database</p> </li>

    20 <li id="GUID-145F724B-4AFF-5987-9DC1-C94D5FE9C54C"><p>navigating the rowset

    21 with a cursor</p> </li>

    22 <li id="GUID-BD487F4B-D14F-5575-95BB-2A1A5ECBC020"><p>row finding and matching </p> </li>

    23 <li id="GUID-56F7E17F-3009-5E2C-A015-CF09D03C98F1"><p>updating or inserting

    24 rows</p> </li>

    25 <li id="GUID-FE9D6B32-74CE-54C7-8DBB-C7578673282F"><p>getting the schema of

    26 the rows within the rowset</p> </li>

    27 <li id="GUID-FA52E8CD-8943-560F-8613-BF7D0E6A05A8"><p>extracting and setting

    28 columns in a row</p> </li>

    29 </ul> <p>A base class is defined for all rowset types by <xref href="GUID-F861EB8F-F621-3E77-8F9A-5E4EFC4E9C2F.dita"><apiname>RDbRowSet</apiname></xref>.

    30 Concrete types of rowset derive from this.</p> <p><b>Table rowset</b> </p> <p>This provides all the rows and columns of a table

    31 as a rowset. Indexes can be used to order the rowset, and to provide fast

    32 key-based row retrieval from the table. It is encapsulated in <xref href="GUID-90ABFA73-6374-367C-BAA9-88CD810035CC.dita"><apiname>RDbTable</apiname></xref>. </p> <p><b>SQL view</b> </p> <p>This provides a rowset based on an SQL query. It

    33 is provided by <xref href="GUID-AE1BEF00-5AA7-3F03-95B0-9E40395EDA6C.dita"><apiname>RDbView</apiname></xref>. An SQL query is encapsulated in <xref href="GUID-A7C9FEFA-A9A9-357F-AF66-FA3A288AF925.dita"><apiname>TDbQuery</apiname></xref>.</p> <p>For

    34 large rowsets, it can be useful to define the balance between memory usage

    35 (greatest if the view stores the complete rowset) and speed (slowest if the

    36 rowset is evaluated for each cursor navigation). This is called the pre-evaluation

    37 window, and is provided by <xref href="GUID-E53A90DF-3589-34BD-B7C3-02371567AF41.dita"><apiname>TDbWindow</apiname></xref>.</p> </section>

    38 </conbody></concept>