Why Isn't There a Built-in Progressive Multiplication Operator in SQL?

SQL's Missing Progressive Multiplication: Why?

The absence of a dedicated aggregate multiplication operator in standard SQL is a frequent point of discussion. While such an operator would simplify calculating the product of column values, its exclusion is justified by several factors.

A major concern is potential data overflow. Multiplication, especially across large datasets, can quickly generate results exceeding the capacity of even the largest SQL data types.

Moreover, the practical need for a dedicated operator is relatively low. Alternative approaches, such as using the PRODUCT function (where available) or performing individual multiplications within a subquery, readily achieve the same outcome.

Alternative Approaches to Progressive Multiplication

Although a direct multiplication operator is missing, several workarounds effectively mimic its functionality. Popular database systems like Oracle, MSSQL, and MySQL provide mathematical functions to accomplish this:

• Oracle: EXP(SUM(LN(column))) or POWER(N,SUM(LOG(column, N)))
• MSSQL: EXP(SUM(LOG(column))) or POWER(N,SUM(LOG(column)/LOG(N)))
• MySQL: EXP(SUM(LOG(column))) or POW(N,SUM(LOG(N,column)))

These methods leverage the logarithmic and exponential properties to compute the product: the sum of logarithms is equivalent to the logarithm of the product, and exponentiation reverses the logarithm.

Illustrative Example

Consider this sample data:

Column

1

2

4

8

Applying the Oracle workaround:

EXP(SUM(LN(Column)))

The result correctly yields 64, the product of the column values.

Handling Negative Numbers

It's crucial to note that these logarithmic approaches don't inherently handle negative numbers. To accommodate negative values, more complex calculations are necessary. Here's an example using SQL Server to address this:

CASE
  WHEN MIN(ABS(data)) = 0 THEN 0
  ELSE
    EXP(SUM(LOG(ABS(NULLIF(data, 0))))) *
    ROUND(0.5 - COUNT(NULLIF(SIGN(SIGN(data) + 0.5), 1)) % 2, 0)
END

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