re code = &#39;DS&#39;;</span></span></code></pre></div>
<h3 id="foreign-key-constraints">Foreign Key Constraints</h3>
<ul>
<li>References to other tables</li>
<li>Usually refers to primary keys in other tables</li>
<li>Usually created to represent relationships when translating an ER diagram into a relational schema</li>
<li>A column or group of columns can be references to a column or group of columns in another table</li>
<li>We can use a column constraint if the foreign key has only 1 column
<ul>
<li><c