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 <?xml version="1.0" encoding="UTF-8"?>
 <chapter id="details.database">
 <chapterinfo>
   <authorgroup>
     <author>&Tony.Bloomfield; &Tony.Bloomfield.mail;</author>
   </authorgroup>
   <date>2011-07-21</date>
   <releaseinfo>4.6</releaseinfo>
 </chapterinfo>
 
 <title>Database</title>
 
 <sect1 id="details.database.usage">
 <title>Using relational databases</title>
 
 <sect2>
 <title>Introduction</title>
 <para>
   As of release 1.0, &kmymoney; allows you to hold your data in a relational
   database. One of the advantages of using this industry-standard format is that
   it may allow you to view your data using one of the graphic front ends such as
   <trademark>OpenOffice.org</trademark> or <trademark>LibreOffice</trademark>,
   perhaps in some format that &kmymoney; currently doesn't
   provide. Also, a little knowledge of SQL (Structured Query Language, the
   language used world-wide to access relational databases) should enable you
   more easily to export data to an external program, for example, a budgeting
   application.
 </para>
 <para/>
 </sect2>
 
 <sect2><title>Preparation</title>
 
 <para>
   To access the database, &kmymoney; uses the SQL module supplied by &Qt;
   Software as part of their &Qt; programming system. This module supports a
   number of different database systems through a collection of drivers. Among
   the more popular open-source systems for which drivers are available are
   <trademark>MySQL</trademark>, SQLite (version 3 and upwards only), and PostgreSQL.
   The module also supports the 'heavier', more industrial, systems such as <trademark
   class="registered">Oracle</trademark> and IBM <trademark class="registered">DB2</trademark>.
 </para>
 
 <para>
   With the exception of SQLite, these systems use a client/server model, where
   the 'client' software sits on 'your' machine, while the server lives on the
   same machine as the database itself, which may be elsewhere on a network. Of
   course, in the normal scenario for a personal finance application such as
   &kmymoney;, 'your' machine acts as both client and server. Your first task
   therefore, having decided which database system you wish to use, is to install
   the client, and most probably server, software.
 </para>
 
 <para>
   In addition to the database software itself, you must also install the
   corresponding &Qt; driver module. Most distributions will include driver
   modules for the more popular databases. Otherwise, check with the <ulink
   url="https://www.qt.io/">&Qt; software web site</ulink> and search for
   'SQL drivers'.
 </para>
 
 <note>
   <para>
     SQLite does not operate on a client/server model; each database is held in a
     regular file, local or remote, accessed using the normal methods supplied by
     the underlying operating system. In this case, therefore, there is only one
     software package and the driver to install. Also, some of the following information,
     particularly that related to administration, may not apply to SQLite.
   </para>
 </note>
 </sect2>
 
 <sect2>
 <title>Administration</title>
 
 <para>
   Looking after databases is a little more complex than dealing with regular
   files. Each system has different methods for performing those necessary
   administrative tasks such as creating databases, assigning permissions to
   various users, producing backups, &etc; Describing these tasks is outside the
   scope of this manual, but all of the supported products provide comprehensive
   reference documentation, and a quick search of the web will point you at many
   tutorials on the subject.
 </para>
 
 <sect3>
 <title>Creating the database</title>
 
 <para>
   Code has been included to create an initial database to hold your data if one
   doesn't exist. However, it is strongly recommended that you pre-create a
   database, because most of the products provide a number of options which may
   be relevant. One that may be of particular importance to some would be the
   designation of the character set (&eg;, UTF-8) to be used for text
   fields.
 </para>
 
 <para>
   At this time, you will also need to specify permissions for various users to
   perform different operations on the database. In most systems, the user who
   creates the database will be automatically assigned all permissions, but this
   is an area in which the documentation should be consulted.
 </para>
 
 <para>
   For your first use of the database, and occasionally at other times when the
   database layout changes, you will need permission (also called privileges) to
   create and alter tables and views (see next paragraph). There may be different
   names for the permission/privilege in different systems, but something like
   <literal>CREATE</literal> and <literal>ALTER</literal> should be commonplace.
   For normal running, you will need to be able to read and write records; these
   are normally defined in SQL as <literal>SELECT</literal>, <literal>INSERT</literal>,
   <literal>UPDATE</literal>, and <literal>DELETE</literal> permissions.
 </para>
 </sect3>
 
 <sect3>
 <title>Creating Tables</title>
 
 <para>
   On your first use, &kmymoney; will attempt to create the necessary table
   structures. In order to achieve the maximum compatibility between various
   database types, only a subset of common data types are used. There may
   nevertheless be situations where a particular type is not supported, and in
   this case, provision has been made to generate the SQL code necessary to
   create tables. This code can then be modified as required and used to create
   the tables outside of &kmymoney;. Should you find yourself in this situation,
   help can usually be obtained from &devlist;. See <link
   linkend="details.database.generatesql">Manual Database Creation</link> for more information.
 </para>
 </sect3>
 </sect2>
 
 <sect2 id="details.database.selectdatabase">
 <title>Creating a Database</title>
 
 <para>
   Using &kmymoney;, open or import an existing data file, or create a new
   one. Then select <menuchoice><guimenu>File</guimenu><guimenuitem>Save as Database</guimenuitem></menuchoice>
   menu item. This will present the following dialog:
 </para>
 
 <screenshot>
   <mediaobject>
   <imageobject>
   <imagedata fileref="select_database.png" format="PNG" />
   </imageobject>
   </mediaobject>
 </screenshot>
 
 <para>
   Complete the fields appropriate to the database type you have selected
   (as usual, mandatory fields will be highlighted)
   and click <guibutton>OK</guibutton> to create the database.
 </para>
 
 <sect3>
 <title>Database Type</title>
 
 <para>
   This box lists all &Qt; SQL drivers installed on your system. Select the
   driver for your database type. If the one you want is not in the list, you
   need to install the appropriate driver. See your distribution documentation,
   or visit the <ulink url="https://www.qt.io/">&Qt; software web site</ulink>
   and search for 'SQL drivers'.
 </para>
 </sect3>
 
 <sect3>
 <title>File (SQLite only)</title>
 <para>
   SQLite has one database per file so enter the filename in which you wish to
   create the database.  To browse the file system, click the icon to the right
   of the filename.  For SQLite databases, the <guilabel>Host name</guilabel>,
   <guilabel>Username</guilabel>, and <guilabel>Password</guilabel> fields are
   not relevant. The SQLite file must have the appropriate read/write permissions
   set by the underlying file system to enable the appropriate access for the
   currently logged-in user.
 </para>
 </sect3>
 
 <sect3>
 <title>Database name (others)</title>
 <para>
   The default database name is <literal>KMyMoney</literal>, but you may choose some other
   name if you like. For some database types, &kmymoney; may not be able to create the
   database, so it must be pre-created using the appropriate administrative procedure.
   However, &kmymoney; will usually be able to create all table structures where necessary.
   If not, you can create them yourself. See <link linkend="details.database.generatesql">Manual
   Database Creation</link> for more information.
 </para>
 </sect3>
 
 <sect3><title>Host name</title>
 <para>
   For the average user, the default name of <quote>localhost</quote>, being the
   machine you are currently using, is correct. For networked databases, enter
   the connected host name.
 </para>
 
 </sect3>
 
 <sect3>
 <title>User name and password</title>
 <para>
   Check the permissions set up on your database, or contact the database
   administrator, for the correct values to use here. The user name must be
   capable of selecting, inserting, updating, and deleting records. If the user
   name is the same as your login name, a password is not normally required.
 </para>
 </sect3>
 </sect2>
 
 <sect2>
 <title>Accessing your data</title>
 
 <sect3>
 <title>Table design</title>
 
 <para>
   To access your data in &kmymoney;, use the <menuchoice><guimenu>File</guimenu><guimenuitem>Open
   Database</guimenuitem></menuchoice> menu item. This will
   open a dialog similar to the above.
 </para>
 
 <note>
 <para>
   If you created your database by first opening a file, and then doing
   <guimenuitem>Save as Database</guimenuitem>, as described above, then any
   subsequent changes to your data are saved only in the database, not in the
   file.  This means that you can use the file as a backup or snapshot of your
   data at a particular time.  To make a new backup like this, open your
   database, choose the <menuchoice><guimenu>File</guimenu><guimenuitem>Save
   As...</guimenuitem></menuchoice> menu item, giving an appropriate file name.  Remember
   to re-open your database, so &kmymoney; does not continue to use the file.
 </para>
 </note>
 
 <para>
   To access your data in other formats, you will need to know a little about how
   it is held in relational databases. By far the easiest way to get a feel for
   this is to open the database in a front-end such as <trademark>OpenOffice.org</trademark>.
   This provides a list of the various tables which make up the database, and
   enables you to see the layout of each of them.
 </para>
 
 <para>
   To extract data, &eg;, into a spreadsheet or external file, it is almost
   invariably necessary to select linked data from more than one table. This is
   done by 'joining' the tables, using a field which is common to each. You can
   find a lot more information about how this is done from the online database
   tutorials mentioned above. The following table lists the fields used to define
   these inter-table relationships.
 </para>
 
 <informaltable>
   <tgroup cols="3">
     <thead>
       <row>
         <entry valign="top">
           <para>Relationship</para>
         </entry>
         <entry valign="top">
           <para>Match</para>
         </entry>
         <entry valign="top">
           <para>With</para>
         </entry>
       </row>
     </thead>
     <tbody>
       <row>
         <entry valign="top">
           <para>Institutions and Accounts</para>
         </entry>
         <entry valign="top">
           <para><literal>kmmInstitutions.id</literal></para>
         </entry>
         <entry valign="top">
           <para><literal>kmmAccounts.institutionId</literal></para>
         </entry>
       </row>
       <row>
         <entry valign="top">
           <para>Accounts Parent/Child</para>
         </entry>
         <entry valign="top">
           <para><literal>kmmAccounts.id</literal></para>
         </entry>
         <entry valign="top">
           <para><literal>kmmAccounts.parentId</literal></para>
         </entry>
       </row>
       <row>
         <entry valign="top">
           <para>Transactions and Splits (see Note 1)</para>
         </entry>
         <entry valign="top">
           <para><literal>kmmTransactions.id</literal></para>
         </entry>
         <entry valign="top">
           <para><literal>kmmSplits.transactionId</literal></para>
         </entry>
       </row>
       <row>
         <entry valign="top">
           <para>Accounts and Splits</para>
         </entry>
         <entry valign="top">
           <para><literal>kmmAccounts.id</literal></para>
         </entry>
         <entry valign="top">
           <para><literal>kmmSplits.accountId</literal></para>
         </entry>
       </row>
       <row>
         <entry valign="top">
           <para>Payees and Splits</para>
         </entry>
         <entry valign="top">
           <para><literal>kmmPayees.id</literal></para>
         </entry>
         <entry valign="top">
           <para><literal>kmmSplits.payeeId</literal></para>
         </entry>
       </row>
       <row>
         <entry valign="top">
           <para>Schedules and Transactions</para>
         </entry>
         <entry valign="top">
           <para><literal>kmmSchedules.id</literal></para>
         </entry>
         <entry valign="top">
           <para><literal>kmmTransactions.id</literal></para>
         </entry>
       </row>
       <row>
         <entry valign="top">
           <para>Transactions and Currencies</para>
         </entry>
         <entry valign="top">
           <para><literal>kmmTransactions.currencyId</literal></para>
         </entry>
         <entry valign="top">
           <para><literal>kmmCurrencies.ISOCode</literal></para>
         </entry>
       </row>
       <row>
         <entry valign="top">
           <para><literal>Accounts and Securities (see Note 2)</literal></para>
         </entry>
         <entry valign="top">
           <para><literal>kmmAccounts.currencyId</literal></para>
         </entry>
         <entry valign="top">
           <para><literal>kmmSecurities.id</literal></para>
         </entry>
       </row>
       <row>
         <entry valign="top">
           <para>Securities and Prices</para>
         </entry>
         <entry valign="top">
           <para><literal>kmmSecurities.id</literal></para>
         </entry>
         <entry valign="top">
           <para><literal>kmmPrices.fromId</literal> or <literal>kmmPrices.toId</literal></para>
         </entry>
       </row>
       <row>
         <entry valign="top">
           <para>Currency Rates</para>
         </entry>
         <entry valign="top">
           <para><literal>kmmCurrencies.ISOCode</literal></para>
         </entry>
         <entry valign="top">
           <para><literal>kmmPrices.fromId</literal> or <literal>kmmPrices.toId</literal></para>
         </entry>
       </row>
     </tbody>
   </tgroup>
 </informaltable>
 
 <para>
   Notes:
 </para>
 
 <para>
   1 &#x2013; txType = &#x201C;N&#x201D; for normal transactions,
   &#x201C;S&#x201D; for scheduled transactions
 </para>
 
 <para>
 2 &#x2013; if kmmAccounts.isStockAccount = &#x201C;Y&#x201D;
 </para>
 </sect3>
 
 <sect3>
 <title>Field formats</title>
 
 <para>
   Several of the data fields are held in an internal format which may not be
   immediately useful to external programs. In these cases, the information has
   been duplicated in both internal and external formats.
 </para>
 
 <para>
   Monetary amounts and share values are shown both in numerator/denominator
   format, and, with a field name suffixed with '<literal>Formatted</literal>',
   in the form as shown on your screens.
 </para>
 
 <para>
   Similarly, some fields, such as account type appear both as a numeric code,
   and in a field suffixed '<literal>String</literal>' in the form and language
   of the application.
 </para>
 </sect3>
 
 <sect3>
 <title>Updating your data</title>
 
 <para>
   Having data in an industry standard format does give you the ability to modify
   it outside the &kmymoney; application. DO NOT DO IT unless you really know
   what you are doing, and always be certain to make a backup copy of your data
   first. If you get it wrong, &kmymoney; may not be able to access your data,
   and you could even end up losing it altogether. You have been warned!
 </para>
 </sect3>
 
 <sect3>
 <title>Stored queries</title>
 
 <para>
   Most database systems allow you to store commonly used queries and procedures,
   and in some cases, these may be held as tables or other objects within your
   database itself. As you will have guessed from the above, all the tables used
   by &kmymoney; begin with the lowercase letters '<literal>kmm</literal>'. This
   standard will be maintained, and only tables beginning with these letters will
   be updated. Thus, provided you avoid these in the naming of your queries &etc;,
   you should not experience any problems.
 </para>
 </sect3>
 </sect2>
 
 <sect2 id="details.database.generatesql">
 <title>Manual database creation</title>
 <note>
   <para>
     This section covers more advanced database usage and may be skipped by the general user.
   </para>
 </note>
 
 <sect3>
 <title>When to use</title>
 <para>
   There may be occasions when &kmymoney; is unable to create the database automatically, or creates it without some
   options required by the user. For example, the database system used may not completely conform
   to standard SQL usage, or support may be introduced for new systems which have not been fully tested in &kmymoney;.
 </para>
 <para>
   Prior to using this facility, you should try just creating the database
   entry itself (&ie; with the <literal>CREATE DATABASE</literal> statement).
   Provided the database exists, &kmymoney; may well be able to create the
   tables, &etc; in the normal database save procedure described above.
 </para>
 </sect3>
 
 <sect3>
 <title>Generating the SQL</title>
 <para>
   If this fails, it is possible to generate the basic SQL commands needed to
   create the various tables, views and indexes required by the application.
   Select the <menuchoice><guimenu>Tools</guimenu><guimenuitem>Generate Database
   SQL</guimenuitem></menuchoice> menu item. This will present the following dialog:
 </para>
 <screenshot>
   <mediaobject>
   <imageobject>
   <imagedata fileref="generate_sql.png" format="PNG" />
   </imageobject>
   </mediaobject>
 </screenshot>
 
 <para>
   On selecting the database type, the appropriate SQL will appear in the <guilabel>SQL for creation</guilabel> text box; this can be edited by the user,
   or saved to a text file by clicking <guibutton>Save SQL</guibutton>. In the latter case, the database
   must be created using the administrative functions provided by the database system.
 </para>
 <para>
   If after editing the text in the dialog, you want &kmymoney; to create the database,
   you will need to complete the other fields in the dialog, as detailed in <link
   linkend="details.database.selectdatabase">Creating a Database</link> above,
   and click <guibutton>Create Tables</guibutton>. Note that, except in the case of
   SQLite, you will need either to include a suitable <literal>CREATE DATABASE</literal> statement
   as the first command, or have previously issued such a command externally to &kmymoney;.
 </para>
 </sect3>
 
 <sect3>
 <title>Warning</title>
 <para>
   You should be very careful editing the definitions of any of the basic tables or views
   (those with names beginning with '<literal>kmm</literal>'). Some changes,
   such as increasing the length of an integer field, may have little impact, but you should not
   remove or change the sequence of any fields, or &kmymoney; may refuse to function, or may corrupt your data.
 </para>
 <para>
   Whilst adding or removing indexes may improve performance, you should also be aware that the opposite
   may happen. Some knowledge of the internal operation of &kmymoney; may help to get the
   best performance in these circumstances.
 </para>
 </sect3>
 
 </sect2>
 
 <sect2>
 <title>Encryption</title>
 
 <para>
   Encryption of data in your database is not currently supported.
 </para>
 </sect2>
 </sect1>
 </chapter>