使用聚合函数时,通常还必须创建GROUPBY子句。 但是,在任何SQL聚合函数中都不会计算Null值。
However, Null values are not evaluated in any SQL aggregate function.
On the other hand,HAVING clauses always contain aggregate functions.
The same behavior applies to regular aggregate functions.
We use the count aggregate function.Combinations with other parts of speech
Many common functions that areused to understand a set of data are aggregating functions.
However, several useful functions are not aggregating functions.因为这些结果不匹配,所以MEDIAN不是聚合函数。
Because these results do not match,MEDIAN is not an aggregating function.
Not all functions are aggregating functions.聚合函数:它们对一组行进行操作,并计算每组的返回值。
Aggregate functions: These operate on a group of rows and calculate a single return value per group.SQLMIN()函数-SQLMIN聚合函数允许我们选择某些列最低(最小)值。
SQL MIN Function- The SQL MIN aggregate function allows us to select the lowest(minimum) value for a.一些聚合函数,比如SUM()和COUNT(),能够很容易的并行执行;.
Queries involving aggregate functions such as SUM() and COUNT() can easily be parallelized.在使用聚合函数时,通常还必须创建一个GROUPBY子句。
When you use aggregate functions, you usually must also create a GROUP BY clause.聚合函数允许在每个CPU中保存中间结果,而不是将中间结果保存在共享数据结构中。
Aggregating functions enable intermediate results to be kept per-CPU instead of in a shared data structure.不过,与聚合函数不同,它们可能针对每个组返回多行。
In contrast to aggregate functions, they can return several rows for each group.SQLMAX()函数-SQLMAX聚合函数允许我们选择某个/些列最高(最大)值。
The SQL MAX aggregate function allows us to select the highest(maximum) value for a certain column.SQLMIN()函数-SQLMIN聚合函数允许我们选择某些列最低(最小)值。
The SQL MIN aggregate function allows us to select the lowest(minimum) value for a certain column.在包含聚合函数的SQL语句中,列出未在SELECT子句中汇总的字段。
In a SQL statement that contains aggregate functions, lists fields that are not summarized in the SELECT clause.SQLMAX()函数-SQLMAX聚合函数允许我们选择某个/些列最高(最大)值。
SQL MAX Function- The SQL MAX aggregate function allows us to select the highest(maximum) value for a.如果您向查询中的所有字段应用了聚合函数,则不必创建GROUPBY子句。
If you apply aggregate functions to all the fields in a query, you do not have to create the GROUP BY clause.GROUPBY子句中选择列表中的列无效,因为该列没有包含在聚合函数或.
The error“Column is invalid in the selectlist because it is not contained in either an aggregate function or….
Swipe up, and you can see all your previous calculations and perform aggregate functions.它被添加到SQL语言中,因为WHERE关键字不能与聚合函数一起使用。
The HAVING was added to SQL because theWHERE keyword cannot be used with aggregate functions.UnemploymentInsurance'在选择列表中无效,因为该列既不包含在聚合函数中,也不包含在GROUPBY子句中。
SalesOrderID' is invalid in the selectlist because it is not contained in either an aggregate function or the GROUP BY clause.它被添加到SQL语言中,因为WHERE关键字不能与聚合函数一起使用。
The HAVING clause was added to SQL because the WHEREkeyword could not be used with aggregate functions.如果expr包含一个函数,那么它可能是内置或用户定义的函数,但不是另一个域聚合函数或SQL聚合函数。
If expr includes a function, it can be either built-in or user-defined,but not another domain aggregate or SQL aggregate function.在SQL中增加HAVING子句原因是,WHERE关键字无法与聚合函数一起使用。
The HAVING was added to SQL because theWHERE keyword cannot be used with aggregate functions.如果expr包括函数,则函数可以是内置的,也可以是用户定义的,但不能是另一域聚合函数或SQL聚合函数。
If expr includes a function, it can be either built-in or user-defined,but not another domain aggregate or SQL aggregate function.它被添加到SQL语言中,因为WHERE关键字不能与聚合函数一起使用。
It was added to the SQL language because the WHEREkeyword could not be used with aggregate functions.