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/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *  https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Other licenses:
 * -----------------------------------------------------------------------------
 * Commercial licenses for this work are available. These replace the above
 * Apache-2.0 license and offer limited warranties, support, maintenance, and
 * commercial database integrations.
 *
 * For more information, please visit: https://www.jooq.org/legal/licensing
 *
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package org.jooq;

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import static org.jooq.SQLDialect.CUBRID;
// ...
import static org.jooq.SQLDialect.DUCKDB;
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import static org.jooq.SQLDialect.H2;
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import static org.jooq.SQLDialect.HSQLDB;
import static org.jooq.SQLDialect.MARIADB;
// ...
import static org.jooq.SQLDialect.MYSQL;
// ...
import static org.jooq.SQLDialect.POSTGRES;
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import static org.jooq.SQLDialect.TRINO;
import static org.jooq.SQLDialect.YUGABYTEDB;

import java.util.Collection;

import org.jetbrains.annotations.NotNull;

/**
 * An ordered-set aggregate function.
 * 
 * An ordered-set aggregate function is an aggregate function with a mandatory
 * Oracle-specific WITHIN GROUP (ORDER BY …) clause. An example is
 * LISTAGG: 

 * SELECT   LISTAGG(TITLE, ', ')
 *          WITHIN GROUP (ORDER BY TITLE)
 * FROM     T_BOOK
 * GROUP BY AUTHOR_ID
 *  The above function groups books by author and aggregates titles
 * into a concatenated string.
 * 
 * Ordered-set aggregate functions can be further converted into window functions
 * using the OVER(PARTITION BY …) clause. For example: 

 * SELECT LISTAGG(TITLE, ', ')
 *        WITHIN GROUP (ORDER BY TITLE)
 *        OVER (PARTITION BY AUTHOR_ID)
 * FROM   T_BOOK
 * 
 *
 * @author Lukas Eder
 */
public interface OrderedAggregateFunction {

    /**
     * Add an WITHIN GROUP (ORDER BY …) clause to the ordered
     * aggregate function
     */
    @NotNull
    @Support({ CUBRID, DUCKDB, H2, HSQLDB, MARIADB, MYSQL, POSTGRES, TRINO, YUGABYTEDB })
    AggregateFilterStep withinGroupOrderBy(OrderField... fields);

    /**
     * Add an WITHIN GROUP (ORDER BY …) clause to the ordered
     * aggregate function
     */
    @NotNull
    @Support({ CUBRID, DUCKDB, H2, HSQLDB, MARIADB, MYSQL, POSTGRES, TRINO, YUGABYTEDB })
    AggregateFilterStep withinGroupOrderBy(Collection> fields);
}