layout: global title: QUALIFY Clause displayTitle: QUALIFY Clause license: | Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You 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

 http://www.apache.org/licenses/LICENSE-2.0

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Description

The QUALIFY clause filters rows after window functions have been evaluated. It can refer to window functions in the SELECT list by alias, or define window functions directly in the QUALIFY condition. When an alias in the SELECT list has the same name as an input column, the input column takes precedence.

Syntax

QUALIFY boolean_expression

Parameters

  • boolean_expression

    Specifies any expression that evaluates to a result type boolean. Two or more expressions may be combined together using the logical operators ( AND, OR ).

    Note

    The current query's SELECT list or the QUALIFY condition must contain at least one window function. Aggregate functions are not allowed in the QUALIFY condition.

Examples

CREATE TABLE dealer (id INT, city STRING, car_model STRING, quantity INT);
INSERT INTO dealer VALUES
    (100, 'Fremont', 'Honda Civic', 10),
    (100, 'Fremont', 'Honda Accord', 15),
    (100, 'Fremont', 'Honda CRV', 7),
    (200, 'Dublin', 'Honda Civic', 20),
    (200, 'Dublin', 'Honda Accord', 10),
    (200, 'Dublin', 'Honda CRV', 3),
    (300, 'San Jose', 'Honda Civic', 5),
    (300, 'San Jose', 'Honda Accord', 8);

-- `QUALIFY` clause referring to a window function in the `SELECT` list by alias.
SELECT city, car_model, RANK() OVER (PARTITION BY car_model ORDER BY quantity) AS rank
FROM dealer
QUALIFY rank = 1;
+--------+------------+----+
|    city|   car_model|rank|
+--------+------------+----+
|San Jose|Honda Accord|   1|
|  Dublin|   Honda CRV|   1|
|San Jose| Honda Civic|   1|
+--------+------------+----+

-- `QUALIFY` clause with a window function directly in the predicate.
SELECT city, car_model
FROM dealer
QUALIFY RANK() OVER (PARTITION BY car_model ORDER BY quantity) = 1;
+--------+------------+
|    city|   car_model|
+--------+------------+
|San Jose|Honda Accord|
|  Dublin|   Honda CRV|
|San Jose| Honda Civic|
+--------+------------+

Related Statements