PL / SQL 来自字符串的字数

Question

你能帮我计算字符串中的字数吗？格式如下：

n_var VARCHAR2(1000) := 'Hello, I like ham pizza more than mozzarella pizza.'

我需要这样的输出：hello => 1, I => 1, like => 1, ham => 1, pizza => 2...

我的想法是使用关联数组，但我不知道该怎么做。谢谢。

Answer 1

这是一种解决方案。它部署正则表达式将字符串中的单词拆分为标记。然后使用简单的聚合函数对这些标记进行计数。所以，纯 SQL 不需要关联数组或任何其他 PL/SQL 集合。

with dat as (
    select 'Hello, I like ham pizza more than mozzarella pizza.' as str from dual
)  , tkns as (
    select regexp_substr(str, '([[:alnum:]]+)', 1, level) as tkn
    from dat
    connect by level <= regexp_count(str, '[\., ]')
)
select tkn, count(*)
from tkns
where tkn is not null
group by tkn
order by tkn
/

毫无疑问，还有更优雅的正则表达式解决方案，但至少这个是可行的。

Answer 2

另一种选择是下面的查询：

select word, count(1) as repeating
  from
  (
    with t(str) as
    (
     select 'Hello, I like ham pizza more than mozzarella pizza' from dual   
    )    
    select regexp_replace(regexp_substr(str,  '[^\ ]+', 1, level),'[^a-zA-Z]','')
        as word
      from t
     cross join dual
    connect by level <= regexp_count(str,  '[^\ ]+') 
   )   
 group by word
 order by repeating desc, word;

WORD       REPEATING
---------- ---------
pizza          2
ham            1
Hello          1
I              1
like           1
more           1
mozzarella     1
than           1

PL / SQL 来自字符串的字数

PL / SQL word count from string

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associative-array