数据库统计函数包括：
1. 计数函数
2. 求和、乘积函数
3. 最值函数
4. 均值、方差、标准差函数
5. 其他数据库函数
详细说明：
Category
Subtype
Function
Usage
Excel Database Functions
Database Functions
DAVERAGE
Calculates the average of values in a field of a list or database, that satisfy specified conditions
Excel Database Functions
Database Functions
DCOUNT
Returns the number of cells containing numbers in a field of a list or database that satisfy specified conditions
Excel Database Functions
Database Functions
DCOUNTA
Returns the number of non-blank cells in a field of a list or database, that satisfy specified conditions
Excel Database Functions
Database Functions
DGET
Returns a single value from a field of a list or database, that satisfy specified conditions
Excel Database Functions
Database Functions
DMAX
Returns the maximum value from a field of a list or database, that satisfy specified conditions
Excel Database Functions
Database Functions
DMIN
Returns the minimum value from a field of a list or database, that satisfy specified conditions
Excel Database Functions
Database Functions
DPRODUCT
Calculates the product of values in a field of a list or database, that satisfy specified conditions
Excel Database Functions
Database Functions
DSTDEV
Calculates the standard deviation (based on a sample of a population) of values in a field of a list or database, that satisfy specified conditions
Excel Database Functions
Database Functions
DSTDEVP
Calculates the standard deviation (based on an entire population) of values in a field of a list or database, that satisfy specified conditions
Excel Database Functions
Database Functions
DSUM
Calculates the sum of values in a field of a list or database, that satisfy specified conditions
Excel Database Functions
Database Functions
DVAR
Calculates the variance (based on a sample of a population) of values in a field of a list or database, that satisfy specified conditions
Excel Database Functions
Database Functions
DVARP
Calculates the variance (based on an entire population) of values in a field of a list or database, that satisfy specified conditions
遗留问题：
这些函数和非数据库函数中的对应部分（如，DCOUNT对COUNT），到底有何异同？
到目前为止，工作中没用过数据库函数，是否说明其并不重要？
