MAX

Description

The MAX function returns the maximum non-NULL value of the expression.

Syntax

MAX(<expr>)

Parameters

Parameters	Description
<expr>	The expression to get the value. Supported types are String, Time, Date, DateTime, TimestampNs, Timestamptz, IPv4, IPv6, UUID, TinyInt, SmallInt, Integer, BigInt, LargeInt, Float, Double, Decimal, Array.

Return Value

Returns the same data type as the input expression. If all records in the group are NULL, the function returns NULL.

Example

-- setup
create table t1(
        k1 int,
        k_string varchar(100),
        k_decimal decimal(10, 2),
        k_array array<int>
) distributed by hash (k1) buckets 1
properties ("replication_num"="1");
insert into t1 values 
    (1, 'apple', 10.01, [10, 20, 30]),
    (1, 'banana', 20.02, [10, 20]),
    (2, 'orange', 30.03, [10, 20, 40]),
    (2, null, null, [10, 20, null]),
    (3, null, null, null);

select k1, max(k_string) from t1 group by k1;

For String type: Returns the maximum string value for each group.

+------+---------------+
| k1   | max(k_string) |
+------+---------------+
|    1 | banana        |
|    2 | orange        |
|    3 | NULL          |
+------+---------------+

select k1, max(k_decimal) from t1 group by k1;

For Decimal type: Returns the maximum high-precision decimal value.

+------+----------------+
| k1   | max(k_decimal) |
+------+----------------+
|    1 |          20.02 |
|    2 |          30.03 |
|    3 |           NULL |
+------+----------------+

select k1, max(k_array) from t1 group by k1;

For Array type: Returns the maximum array value for each group(Compare elements one by one; null is the smallest element.).

+------+--------------+
| k1   | max(k_array) |
+------+--------------+
|    1 | [10, 20, 30] |
|    2 | [10, 20, 40] |
|    3 | NULL         |
+------+--------------+

select max(k_string) from t1 where k1 = 3;

When all values in the group are NULL, returns NULL.

+---------------+
| max(k_string) |
+---------------+
| NULL          |
+---------------+

select max(k_string) from t1;

Returns the maximum value across all data.

+---------------+
| max(k_string) |
+---------------+
| orange        |
+---------------+