t-sql:计算 varchar 列中单词的出现次数

问题描述

我想使用 ContainsTable 获取嵌入在名为 description 的 t-sql nvarchar 列中的单个单词的计数.如果我提供红色"或绿色"的标准，我怎么知道哪个真正匹配?简而言之，我正在尝试进行字数统计，并且正在寻找最佳方法.

I want to use ContainsTable to get counts on individual words embedded in a t-sql nvarchar column called description. If I provide the criteria of Red Or Green, how can I tell which one actually matched off? In short, i am trying to do word counts and am looking for the best approach.

提前致谢

推荐答案

给你:

drop function dbo.CountOccurrencesOfWord
go

create function dbo.CountOccurrencesOfWord(
    @text varchar(max),
    @word varchar(8000)
)
returns int
as 
begin 
    declare 
        @index int = charindex(@word, @text, 1),
        @len int = len(@word),
        @count int = 0
    while @index > 0  begin             
        set @count = @count + 1
        set @index = charindex(@word, @text, @index + @len)
    end
    return @count
end

GO

if object_id('tempdb..#example') is not null
    drop table #example
create table #example(
    description nvarchar(4000) not null
)

insert into #example select 'red yellow green red white blue red redred red green red'
insert into #example select 'red yellow green red'
insert into #example select 'orange grey green'
insert into #example select ''
insert into #example select 'magenta aqua cyan'

select dbo.CountOccurrencesOfWord(description, 'red'), description
from #example

注意事项 - 这种逻辑在 t-sql 中可能非常昂贵.

word of caution- this kind of logic can be quite costly in t-sql.