top 运算符top operator

返回按指定列排序的前 N 列。Returns the first N records sorted by the specified columns.

T | top 5 by Name desc nulls last

语法Syntax

T | top NumberOfRows by Expression [asc | desc] [nulls first | nulls last]T | top NumberOfRows by Expression [asc | desc] [nulls first | nulls last]

参数Arguments

  • NumberOfRows:要返回的 T 的行数。NumberOfRows : The number of rows of T to return. 可以指定任何数值表达式。You can specify any numeric expression.
  • 表达式 :要作为排序依据的标量表达式。Expression : A scalar expression by which to sort. 值的类型必须是数字、日期、时间或字符串。The type of the values must be numeric, date, time or string.
  • ascdesc(默认)可能会控制实际从范围“底部”还是“顶部”进行选择。asc or desc (the default) may appear to control whether selection is actually from the "bottom" or "top" of the range.
  • nulls firstasc 顺序的默认值)或 nulls lastdesc 顺序的默认值)可以用来控制 null 值是在范围的开头还是结尾。nulls first (the default for asc order) or nulls last (the default for desc order) may appear to control whether null values will be at the beginning or the end of the range.

提示

top 5 by name 等效于语义和性能透视中的 sort by name | take 5 表达式。top 5 by name is equivalent to the expression sort by name | take 5 both from semantic and performance perspectives.

请参阅See also

  • 使用 top-nested 运算符可生成分层的(嵌套的)排名靠前的结果。Use top-nested operator to produce hierarchical (nested) top results.