ClickHouse/docs/en/sql-reference/aggregate-functions/reference/any.md

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any

Selects the first encountered value of a column.

:::warning As a query can be executed in arbitrary order, the result of this function is non-deterministic. If you need an arbitrary but deterministic result, use functions min or max. :::

By default, the function never returns NULL, i.e. ignores NULL values in the input column. However, if the function is used with the RESPECT NULLS modifier, it returns the first value reads no matter if NULL or not.

Syntax

any(column) [RESPECT NULLS]

Aliases any(column) (without RESPECT NULLS)

• any_value
• first_value.

Alias for any(column) RESPECT NULLS

• anyRespectNulls, any_respect_nulls
• firstValueRespectNulls, first_value_respect_nulls
• anyValueRespectNulls, any_value_respect_nulls

Parameters

• column: The column name.

Returned value

The first value encountered.

:::note The return type of the function is the same as the input, except for LowCardinality which is discarded. This means that given no rows as input it will return the default value of that type (0 for integers, or Null for a Nullable() column). You might use the -OrNull combinator ) to modify this behaviour. :::

Implementation details

In some cases, you can rely on the order of execution. This applies to cases when SELECT comes from a subquery that uses ORDER BY.

When a SELECT query has the GROUP BY clause or at least one aggregate function, ClickHouse (in contrast to MySQL) requires that all expressions in the SELECT, HAVING, and ORDER BY clauses be calculated from keys or from aggregate functions. In other words, each column selected from the table must be used either in keys or inside aggregate functions. To get behavior like in MySQL, you can put the other columns in the any aggregate function.

Example

Query:

CREATE TABLE tab (city Nullable(String)) ENGINE=Memory;

INSERT INTO tab (city) VALUES (NULL), ('Amsterdam'), ('New York'), ('Tokyo'), ('Valencia'), (NULL);

SELECT any(city), anyRespectNulls(city) FROM tab;

┌─any(city)─┬─anyRespectNulls(city)─┐
│ Amsterdam │ ᴺᵁᴸᴸ                  │
└───────────┴───────────────────────┘