/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
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 * -----------------------------------------------------------------------------
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 * commercial database integrations.
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 * For more information, please visit: https://www.jooq.org/legal/licensing
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package org.jooq;

/**
 * An ordered-set aggregate function.
 * <p>
 * An ordered-set aggregate function is an aggregate function with a mandatory
 * Oracle-specific <code>WITHIN GROUP (ORDER BY …)</code> clause. An example is
 * <code>LISTAGG</code>: <pre><code>
 * SELECT   LISTAGG(TITLE, ', ')
 *          WITHIN GROUP (ORDER BY TITLE)
 * FROM     T_BOOK
 * GROUP BY AUTHOR_ID
 * </code></pre> The above function groups books by author and aggregates titles
 * into a concatenated string.
 * <p>
 * Ordered-set aggregate functions can be further converted into window functions
 * using the <code>OVER(PARTITION BY …)</code> clause. For example: <pre><code>
 * SELECT LISTAGG(TITLE, ', ')
 *        WITHIN GROUP (ORDER BY TITLE)
 *        OVER (PARTITION BY AUTHOR_ID)
 * FROM   T_BOOK
 * </code></pre>
 *
 * @author Lukas Eder
 */
public interface OptionallyOrderedAggregateFunction<T>
extends
    OrderedAggregateFunction<T>,
    AggregateFilterStep<T>
{

}
