unique.java

torque服务器源代码

package org.apache.torque.engine.database.model;

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import java.util.List;

/**
 * Information about unique columns of a table.  This class assumes
 * that in the underlying RDBMS, unique constraints and unique indices
 * are roughly equivalent.  For example, adding a unique constraint to
 * a column also creates an index on that column (this is known to be
 * true for MySQL and Oracle).
 *
 * @author <a href="mailto:[e-mail]">Jason van Zyl</a>
 * @author <a href="mailto:[e-mail]">Daniel Rall</a>
 * @version $Id: Unique.java,v 1.1 2003/02/10 13:20:58 mpoeschl Exp $
 */
public class Unique extends Index
{
    /**
     * Returns <code>true</code>.
     *
     * @return true
     */
    public final boolean isUnique()
    {
        return true;
    }

    /**
     * String representation of the index. This is an xml representation.
     *
     * @return string representation in xml
     */
    public String toString()
    {
        StringBuffer result = new StringBuffer();
        result.append(" <unique name=\"")
            .append(getName())
            .append("\">\n");

        List columns = getColumns();
        for (int i = 0; i < columns.size(); i++)
        {
            result.append("  <unique-column name=\"")
                .append(columns.get(i))
                .append("\"/>\n");
        }
        result.append(" </unique>\n");
        return result.toString();
    }
}