Subversion-Projekte lars-tiefland.prado

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<h1>The SQL</h1>
<p>If you are not using stored procedures, the most important part of a
statement-type element is the SQL. You can use any SQL statement that is valid
for your database system. Since SQLMap passes the SQL through to a standard
libraries (Adodb for PHP), you can use any statement with SQLMap that you
could use without SQLMap. You can use whatever functions your database system
supports, and even send multiple statements, so long as your driver or
provider supports them.</p>


<h2>Escaping XML symbols</h2>
<p>Because you are combining SQL and XML in a
single document, conflicts can occur. The most common conflict is the
greater-than and less-than symbols (&gt;&lt;). SQL statements use these symbols as
operators, but they are reserved symbols in XML. A simple solution is to
escape the SQL statements that uses XML reserved symbols within a CDATA
element. The following example demonstrates this.

<com:TTextHighlighter Language="xml" CssClass="source">
<statement id="SelectPersonsByAge" parameterClass="int" resultClass="Person">
  <![CDATA[
     SELECT * FROM PERSON WHERE AGE > #value#
  ]]>
</statement>
</com:TTextHighlighter>

<h2>Auto-Generated Keys</h2>
<p>Many database systems support auto-generation of primary key fields, as a
vendor extension. Some vendors pre-generate keys (e.g. Oracle), some vendors
post-generate keys (e.g. MS-SQL Server and MySQL). In either case, you can
obtain a pre-generated key using a <tt>&lt;selectKey&gt;</tt> stanza within an
<tt>&lt;insert&gt;</tt> element. The following example shows an <tt>&lt;insert&gt;</tt>
statement for either approach.</p>

<com:TTextHighlighter Language="xml" CssClass="source">
<!-- Oracle SEQUENCE Example using .NET 1.1 System.Data.OracleClient -->
<insert id="insertProduct-ORACLE" parameterClass="product">
  <selectKey resultClass="int" type="pre" property="Id" >
     SELECT STOCKIDSEQUENCE.NEXTVAL AS VALUE FROM DUAL
  </selectKey>
  insert into PRODUCT (PRD_ID,PRD_DESCRIPTION) values (#id#,#description#)
</insert>

<!-- Microsoft SQL Server IDENTITY Column Example -->
<insert id="insertProduct-MS-SQL" parameterClass="product">
  insert into PRODUCT (PRD_DESCRIPTION)
  values (#description#)
 <selectKey resultClass="int" type="post" property="id" >
   select @@IDENTITY as value
 </selectKey>
</insert>

<!-- MySQL Example -->
<insert id="insertProduct-MYSQL" parameterClass="product">
  insert into PRODUCT (PRD_DESCRIPTION)
  values (#description#)
 <selectKey resultClass="int" type="post" property="id" >
   select LAST_INSERT_ID() as value
 </selectKey>
</insert>
</com:TTextHighlighter>

<h2><tt>&lt;generate&gt;</tt> tag</h2>
<p>You can use SQLMap to execute any SQL statement your application requires.
When the requirements for a statement are simple and obvious, you may not even
need to write a SQL statement at all. The <tt>&lt;generate&gt;</tt> tag can be used to
create simple SQL statements automatically, based on a <tt>&lt;parameterMap&gt;</tt>
element. The four CRUD statement types (insert, select, update, and delete)
are supported. For a select, you can select all or select by a key (or keys).
The following example shows an example of generating the usual array of
CRUD statements.</p>

<div class="note"><b class="tip">Important:</b>
The intended use of the <tt>&lt;generate&gt;</tt> tag is to save developers the trouble
of coding mundane SQL statements (and only mundane statements). It is not
meant as a object-to-relational mapping tool. There are many frameworks that
provide extensive object-to-relational mapping features. The <tt>&lt;generate&gt;</tt>
tag is not a replacement for any of those. When the <tt>&lt;generate&gt;</tt> tag does
not suit your needs, use a conventional statement instead.
</div>

<com:TTextHighlighter Language="xml" CssClass="source">
  <parameterMap id="insert-generate-params">
    <parameter property="Name" column="Category_Name"/>
    <parameter property="Guid" column="Category_Guid" dbType="UniqueIdentifier"/>
  </parameterMap>

  <parameterMap id="update-generate-params" extends="insert-generate-params">
    <parameter property="Id" column="Category_Id" />
  </parameterMap>

  <parameterMap id="delete-generate-params">
    <parameter property="Id" column="Category_Id" />
    <parameter property="Name" column="Category_Name"/>
  </parameterMap>

  <parameterMap id="select-generate-params">
    <parameter property="Id" column="Category_Id" />
    <parameter property="Name" column="Category_Name"/>
    <parameter property="Guid" column="Category_Guid" dbType="UniqueIdentifier"/>
  </parameterMap>

  <update id="UpdateCategoryGenerate" parameterMap="update-generate-params">
    <generate table="Categories" by="Category_Id"/>
  </update>

  <delete id="DeleteCategoryGenerate" parameterMap="delete-generate-params">
    <generate table="Categories" by="Category_Id, Category_Name"/>
  </delete>

  <select id="SelectByPKCategoryGenerate" resultClass="Category" 
                  parameterClass="Category" parameterMap="select-generate-params">
    <generate table="Categories" by="Category_Id"/>
  </select>

  <select id="SelectAllCategoryGenerate" resultClass="Category"
          parameterMap="select-generate-params">
    <generate table="Categories" />
  </select>

  <insert id="InsertCategoryGenerate" parameterMap="insert-generate-params">
    <selectKey property="Id" type="post" resultClass="int">
      select @@IDENTITY as value
    </selectKey>
    <generate table="Categories" />
  </insert>
</com:TTextHighlighter>

<p>The tag generates ANSI SQL, which should work with any compliant database.
Special types, such as blobs, are not supported, and vendor-specific types are
also not supported. But, the generate tag does keep the simple things simple.</p>

<div class="note"><b class="tip">Note:</b>
The SQL is generated when the DataMapper instance is built and can be cached
afterward, so there is no performance impact at execution time.
</div>

<p>The generate tag supports two attributes.</p>

<!-- tabular: align=|l|l|l|, width=(0.2 0.4 0.2) --> 
<table class="tabular">
        <tr><th>Attribute</th><th>Description</th><th>Required</th></tr>
        <tr>
                <td><tt>table</tt></td>
                <td>specifies the table name to use in the SQL statement</td>
                <td>yes</td>
        </tr>
        <tr>
                <td><tt>by</tt></td>
                <td>specifies the columns to use in a WHERE clause</td>
                <td>no</td>
        </tr>
</table>

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