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4.0 KiB
slug | sidebar_position |
---|---|
/en/sql-reference/aggregate-functions/reference/argmin | 110 |
argMin
Calculates the arg
value for a minimum val
value. If there are multiple rows with equal val
being the maximum, which of the associated arg
is returned is not deterministic.
Both parts the arg
and the min
behave as aggregate functions, they both skip Null
during processing and return not Null
values if not Null
values are available.
Syntax
argMin(arg, val)
Arguments
arg
— Argument.val
— Value.
Returned value
arg
value that corresponds to minimumval
value.
Type: matches arg
type.
Example
Input table:
┌─user─────┬─salary─┐
│ director │ 5000 │
│ manager │ 3000 │
│ worker │ 1000 │
└──────────┴────────┘
Query:
SELECT argMin(user, salary) FROM salary
Result:
┌─argMin(user, salary)─┐
│ worker │
└──────────────────────┘
Extended example
CREATE TABLE test
(
a Nullable(String),
b Nullable(Int64)
)
ENGINE = Memory AS
SELECT *
FROM VALUES((NULL, 0), ('a', 1), ('b', 2), ('c', 2), (NULL, NULL), ('d', NULL));
select * from test;
┌─a────┬────b─┐
│ ᴺᵁᴸᴸ │ 0 │
│ a │ 1 │
│ b │ 2 │
│ c │ 2 │
│ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │
│ d │ ᴺᵁᴸᴸ │
└──────┴──────┘
SELECT argMin(a, b), min(b) FROM test;
┌─argMin(a, b)─┬─min(b)─┐
│ a │ 0 │ -- argMin = a because it the first not `NULL` value, min(b) is from another row!
└──────────────┴────────┘
SELECT argMin(tuple(a), b) FROM test;
┌─argMin(tuple(a), b)─┐
│ (NULL) │ -- The a `Tuple` that contains only a `NULL` value is not `NULL`, so the aggregate functions won't skip that row because of that `NULL` value
└─────────────────────┘
SELECT (argMin((a, b), b) as t).1 argMinA, t.2 argMinB from test;
┌─argMinA─┬─argMinB─┐
│ ᴺᵁᴸᴸ │ 0 │ -- you can use `Tuple` and get both (all - tuple(*)) columns for the according max(b)
└─────────┴─────────┘
SELECT argMin(a, b), min(b) FROM test WHERE a IS NULL and b IS NULL;
┌─argMin(a, b)─┬─min(b)─┐
│ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ -- All aggregated rows contains at least one `NULL` value because of the filter, so all rows are skipped, therefore the result will be `NULL`
└──────────────┴────────┘
SELECT argMin(a, (b, a)), min(tuple(b, a)) FROM test;
┌─argMin(a, tuple(b, a))─┬─min(tuple(b, a))─┐
│ d │ (NULL,NULL) │ -- 'd' is the first not `NULL` value for the min
└────────────────────────┴──────────────────┘
SELECT argMin((a, b), (b, a)), min(tuple(b, a)) FROM test;
┌─argMin(tuple(a, b), tuple(b, a))─┬─min(tuple(b, a))─┐
│ (NULL,NULL) │ (NULL,NULL) │ -- argMin returns (NULL,NULL) here because `Tuple` allows to don't skip `NULL` and min(tuple(b, a)) in this case is minimal value for this dataset
└──────────────────────────────────┴──────────────────┘
SELECT argMin(a, tuple(b)) FROM test;
┌─argMin(a, tuple(b))─┐
│ d │ -- `Tuple` can be used in `min` to not skip rows with `NULL` values as b.
└─────────────────────┘
See also