UNIFORM

Syntax

UNIFORM(<min> , <max> , <gen>)

Description

The UNIFORM() function returns an integer or a float that follows a uniform distribution.

• The min and max parameters must be scalar values that do not change with row iteration. For example, constants or scalar functions. In PL, they can also be expressions like @v1 or 1+@v3.
• In MySQL mode, if both min and max are integers, the output of the UNIFORM() function is an integer; otherwise, the output is a float.
• gen is a numerical generation function, typically using the RANDOM() function. If the input value is a constant, the output of the UNIFORM() function is also a constant.

Examples

The following example generates an integer between 1 and 10 uniformly.

SELECT v, COUNT(*) FROM (SELECT UNIFORM(1, 10, RANDOM()) v FROM TABLE(GENERATOR(1000000))) x GROUP BY v ORDER BY v;
+------+----------+
| v    | count(*) |
+------+----------+
|    1 |   100738 |
|    2 |   100119 |
|    3 |   100223 |
|    4 |    99537 |
|    5 |   100125 |
|    6 |   100001 |
|    7 |   100275 |
|    8 |    99235 |
|    9 |    99837 |
|   10 |    99910 |
+------+----------+
10 rows in set (0.002 sec)

The following example shows that the return type is related to the parameter type.

SELECT UNIFORM(0.0, 10, RANDOM()) FROM TABLE(GENERATOR(4)) ORDER BY 1;
+----------------------------+
| UNIFORM(0.0, 10, RANDOM()) |
+----------------------------+
|         2.3520877625884653 |
|          4.155845987385725 |
|          8.323930497420852 |
|          9.844002748532109 |
+----------------------------+
4 rows in set (0.001 sec)

SELECT UNIFORM(0, 10, RANDOM()) FROM TABLE(GENERATOR(4)) ORDER BY 1;
+--------------------------+
| UNIFORM(0, 10, RANDOM()) |
+--------------------------+
|                        0 |
|                        4 |
|                        8 |
|                        9 |
+--------------------------+
4 rows in set (0.001 sec)