VAR_POP¶

Syntax¶

Aggregate function

VAR_POP( [ DISTINCT ] <expr1> )

Window function

VAR_POP( [ DISTINCT ] <expr1> ) OVER (
                                     [ PARTITION BY <expr2> ]
                                     [ ORDER BY <expr3> [ ASC | DESC ] [ <window_frame> ] ]
                                     )

For detailed window_frame syntax, see Window function syntax and usage.

Arguments¶

expr1

The expr1 should evaluate to one of the numeric data types.

expr2

This is the optional expression to partition by.

expr3

This is the optional expression to order by within each partition.

Returns¶

The data type of the returned value is NUMBER(<precision>, <scale>). The scale depends upon the values being processed.

Usage notes¶

• When passed a VARCHAR expression, this function implicitly casts the input to floating point values. If the cast cannot be performed, an error is returned.

• When this function is called as a window function with an OVER clause that contains an ORDER BY clause:

  • A window frame is required. If no window frame is specified explicitly, the following implied window frame is used:

    RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW

    For more information about window frames, including syntax, usage notes, and examples, see Window function syntax and usage.

  • Using the keyword DISTINCT inside the window function is prohibited and results in a compile-time error.

Examples¶

This example shows how to use the VAR_POP function:

Create and fill a table:

create table aggr(k int, v decimal(10,2), v2 decimal(10, 2));
insert into aggr values 
   (1, 10, null),
   (2, 10, 11), 
   (2, 20, 22), 
   (2, 25, null), 
   (2, 30, 35);

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Query the table:

SELECT k, var_pop(v), var_pop(v2) 
    FROM aggr 
    GROUP BY k
    ORDER BY k;
+---+---------------+---------------+
| K |    VAR_POP(V) |   VAR_POP(V2) |
|---+---------------+---------------|
| 1 |  0.0000000000 |          NULL |
| 2 | 54.6875000000 | 96.2222222222 |
+---+---------------+---------------+

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