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<p><a id="BABBHBGA" name="BABBHBGA"></a><a id="TDDDG42220" name="TDDDG42220"></a></p>
<div class="sect2">
<h1>Ensuring that Variables, Constants, and Parameters Have Correct Data Types</h1>
<a name="BEGIN" id="BEGIN"></a>
<p><a id="sthref410" name="sthref410"></a><a id="sthref411" name="sthref411"></a><a id="sthref412" name="sthref412"></a>After <a href="tdddg_subprograms019.htm#CIHBGDBA">"Tutorial: Declaring Variables and Constants in a Subprogram"</a>, the code for the <code>calculate_score</code> function, in the body of the package <code>EMP_EVAL</code>, is:</p>
<pre xml:space="preserve" class="oac_no_warn">
FUNCTION calculate_score ( evaluation_id IN NUMBER
                          , performance_id IN NUMBER )
                          RETURN NUMBER AS
  n_score       NUMBER(1,0);                -- variable
  n_weight      NUMBER;                     -- variable
  max_score     CONSTANT NUMBER(1,0) := 9;  -- constant, initial value 9
  max_weight    CONSTANT NUMBER(8,8) := 1;  -- constant, initial value 1
  BEGIN
    /* TODO implementation required */
    RETURN NULL;
  END calculate_score;
</pre>
<p>The variables, constants, and parameters of the function represent values from the tables <code>SCORES</code> (created in <a href="tdddg_objects007.htm#BABEECGC">"Creating Tables with the CREATE TABLE Statement"</a>) and <code>PERFORMANCE_PARTS</code> (created in <a href="tdddg_objects006.htm#BABJEJEG">"Tutorial: Creating a Table with the Create Table Tool"</a>):</p>
<ul>
<li>
<p>Variable <code>n_score</code> will hold a value from the <code>SCORE</code> column of the <code>SCORES</code> table, and constant <code>max_score</code> will be compared to such values.</p>
</li>
<li>
<p>Variable <code>n_weight</code> will hold a value from the <code>WEIGHT</code> column of the <code>PERFORMANCE_PARTS</code> table, and constant <code>max_weight</code> will be compared to such values.</p>
</li>
<li>
<p>Parameter <code>evaluation_id</code> will hold a value from the <code>EVALUATION_ID</code> column of the <code>SCORES</code> table.</p>
</li>
<li>
<p>Parameter <code>performance_id</code> will hold a value from the <code>PERFORMANCE_ID</code> column of the <code>SCORES</code> table.</p>
</li>
</ul>
<p>Therefore, each variable, constant, and parameter has the same data type as its corresponding column.</p>
<p>If the data types of the columns change, you want the data types of the variables, constants, and parameters to change to the same data types; otherwise, the <code>calculate_score</code> function will be invalidated.</p>
<p>To ensure that the data types of the variables, constants, and parameters will always match those of the columns, declare them with the <a id="sthref413" name="sthref413"></a><a id="sthref414" name="sthref414"></a><code>%TYPE</code> attribute. The <code>%TYPE</code> attribute supplies the data type of a table column or another variable, ensuring the correct data type assignment.</p>
<div class="helpinfonotealso">
<h2>Related Topics</h2>
<p><a href="javascript:open('http://www.oracle.com/pls/db112/lookup?id=LNPLS99970','newWindow').focus()"><span class="italic">Oracle Database PL/SQL Language Reference</span></a> for more information about the <code>%TYPE</code> attribute</p>
<p><a href="javascript:open('http://www.oracle.com/pls/db112/lookup?id=LNPLS01352','newWindow').focus()"><span class="italic">Oracle Database PL/SQL Language Reference</span></a> for the syntax of the <code>%TYPE</code> attribute</p>
<p><a href="tdddg_subprograms018.htm#CIHBCBHC">Declaring and Assigning Values to Variables and Constants</a></p>
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