<?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, &kappname; 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
  OpenOffice.org<trademark class="copyright"/> or LibreOffice<trademark
  class="copyright"/>, perhaps in some format that &kappname; 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, &kappname; 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
  MySQL<trademark class="registered"/>, SQLite (version 3 and upwards only), and PostgreSQL. The module also
  supports the 'heavier', more industrial, systems such as Oracle<trademark
  class="registered"/> and IBM DB2<trademark class="registered"/>.
</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
  &kappname;, '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="http://qt-project.org">&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
  CREATE and ALTER should be commonplace. For normal running, you will need to
  be able to read and write records; these are normally defined in SQL as
  SELECT, INSERT, UPDATE, and DELETE permissions.
</para>
</sect3>

<sect3>
<title>Creating Tables</title>

<para>
  On your first use, &kappname; 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 &kappname;. 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 &kappname;, open or import an existing data file, or create a new
  one. Then select <guimenuitem>Save as Database</guimenuitem> from the
  <guimenu>File</guimenu> menu. 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="http://qt-project.org/" type="">&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 KMyMoney, but you may choose some other name if
  you like.
  For some database types, &kappname; may not be able to create the
  database, so it must be pre-created using the appropriate administrative
  procedure. However, &kappname; 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 &kappname;, use the <guimenuitem>Open
  Database</guimenuitem> entry in the <guimenu>File</guimenu> menu. 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, do <menuchoice><guimenu>File</guimenu><guimenuitem>Save
  As...</guimenuitem></menuchoice>, giving an appropriate file name.  Remember
  to re-open your database, so &kappname; 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 OpenOffice.org. 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>kmmInstitutions.id</para>
        </entry>
        <entry valign="top">
          <para>kmmAccounts.institutionId</para>
        </entry>
      </row>
      <row>
        <entry valign="top">
          <para>Accounts Parent/Child</para>
        </entry>
        <entry valign="top">
          <para>kmmAccounts.id</para>
        </entry>
        <entry valign="top">
          <para>kmmAccounts.parentId</para>
        </entry>
      </row>
      <row>
        <entry valign="top">
          <para>Transactions and Splits (see Note 1)</para>
        </entry>
        <entry valign="top">
          <para>kmmTransactions.id</para>
        </entry>
        <entry valign="top">
          <para>kmmSplits.transactionId</para>
        </entry>
      </row>
      <row>
        <entry valign="top">
          <para>Accounts and Splits</para>
        </entry>
        <entry valign="top">
          <para>kmmAccounts.id</para>
        </entry>
        <entry valign="top">
          <para>kmmSplits.accountId</para>
        </entry>
      </row>
      <row>
        <entry valign="top">
          <para>Payees and Splits</para>
        </entry>
        <entry valign="top">
          <para>kmmPayees.id</para>
        </entry>
        <entry valign="top">
          <para>kmmSplits.payeeId</para>
        </entry>
      </row>
      <row>
        <entry valign="top">
          <para>Schedules and Transactions</para>
        </entry>
        <entry valign="top">
          <para>kmmSchedules.id</para>
        </entry>
        <entry valign="top">
          <para>kmmTransactions.id</para>
        </entry>
      </row>
      <row>
        <entry valign="top">
          <para>Transactions and Currencies</para>
        </entry>
        <entry valign="top">
          <para>kmmTransactions.currencyId</para>
        </entry>
        <entry valign="top">
          <para>kmmCurrencies.ISOCode</para>
        </entry>
      </row>
      <row>
        <entry valign="top">
          <para>Accounts and Securities (see Note 2)</para>
        </entry>
        <entry valign="top">
          <para>kmmAccounts.currencyId</para>
        </entry>
        <entry valign="top">
          <para>kmmSecurities.id</para>
        </entry>
      </row>
      <row>
        <entry valign="top">
          <para>Securities and Prices</para>
        </entry>
        <entry valign="top">
          <para>kmmSecurities.id</para>
        </entry>
        <entry valign="top">
          <para>kmmPrices.fromId or kmmPrices.toId</para>
        </entry>
      </row>
      <row>
        <entry valign="top">
          <para>Currency Rates</para>
        </entry>
        <entry valign="top">
          <para>kmmCurrencies.ISOCode</para>
        </entry>
        <entry valign="top">
          <para>kmmPrices.fromId or kmmPrices.toId</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 'Formatted', 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 'String' 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 &kappname; 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, &kappname; 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 &kappname; begin with the lowercase letters 'kmm'. 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 &kappname; 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 &kappname;.
</para>
<para>
  Prior to using this facility, you should try just creating the database entry itself (&ie; with the CREATE DATABASE
  statement). Provided the database exists, &kappname; 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 <guimenuitem>Generate Database SQL</guimenuitem> from the
  <guimenu>Tools</guimenu> menu. 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 &kappname; 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 CREATE DATABASE statement
  as the first command, or have previously issued such a command externally to &kappname;
</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 'kmm'). 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 &kappname; 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 &kappname; 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>
