SQL 统计字段中的字数

Question

I'd like to make an SQL query where the condition is that column1 contains three or more words. Is there something to do that?

Answer 1

maybe try counting spaces ?

SELECT * 
FROM table
WHERE (LENGTH(column1) - LENGTH(replace(column1, ' ', ''))) > 1

and assume words is number of spaces + 1

Answer 2

如果你想要一个列包含三个或更多单词的条件， 并且你希望它在一堆数据库中工作， 并且我们假设单词由单个空格分隔，那么你可以使用like ：

where column1 like '% % %'

Answer 3

In Postgres you can use regexp_split_to_array() for this:

select *
from the_table
where array_length(regexp_split_to_array(the_column, '\s+'), 1) >= 3;

This will split the contents of the column the_column into array elements. One ore more whitespace are used as the delimiter. It won't respect "quoted" spaces though. The value 'one "two three" four' will be counted as four words.

Answer 4

The best way to do this, is to NOT do this.

Instead, you should use the application layer to count the words during INSERT and save the word count into its own column.

While I like, and upvoted, some of the answers here, all of them will be very slow and not 100% accurate.

I know people want a simple answer to SELECT the word count, but it just is NOT POSSIBLE with accuracy and speed.

If you want it to be 100% accurate, and very fast, then use this solution.

Steps to solve:

1. Add a column to your table and index it: ALTER TABLE tablename ADD COLUMN wordcount INT UNSIGNED NULL, ADD INDEX idxtablename_count (wordcount ASC); .
2. Before doing your INSERT, count the number of words using your application. For example in PHP: $count = str_word_count($somevalue);
3. During the INSERT, include the value of $count for the column wordcount like insert into tablename (col1, col2, col3, wordcount) values (val1, val2, val3, $count);

Then your select statement becomes super easy, clean, uber-fast, and 100% accurate.

select * from tablename where wordcount >= 3;

Also remember when you are updating any rows that you will need to recount the words for that column.

Answer 5

With ClickHouse DB You can use splitByWhitespace() function.

Refer: https://clickhouse.com/docs/en/sql-reference/functions/splitting-merging-functions#splitbywhitespaces

Answer 6

This can work:

SUM(LENGTH(a) - LENGTH(REPLACE(a, ' ', '')) + 1)

Where a is the string column. It will count the number of spaces, which is 1 less than the number of words.

Answer 7

For "n" or more words

select *
from table
where (length(column)- length(replace(column, " ", "")) + 1) >= n

PS: This would not work if words have multiple spaces between them.

Answer 8

To handle multiple spaces too, use the method shown here

Declare @s varchar(100)
set @s='  See      how many                        words this      has  '
set @s=ltrim(rtrim(@s))

while charindex('  ',@s)>0
Begin
    set @s=replace(@s,'  ',' ')
end

select len(@s)-len(replace(@s,' ',''))+1 as word_count

https://exploresql.com/2018/07/31/how-to-count-number-of-words-in-a-sentence/

Answer 9

I think David nailed it above. However, as a more complete answer:

LENGTH(RTRIM(LTRIM(REPLACE(column1,'  ', ' ')))) - LENGTH(REPLACE(RTRIM(LTRIM(REPLACE(column1, '  ', ' '))), ' ', '')) + 1 AS number_of_words

This will remove double spaces, as well as leading and trailing spaces in your string.

Of course, you may go further by adding replacements for more than 2 spaces in a row...

Answer 10

None of the other answers seem to take multiple spaces into account. For example, a lot of people use two spaces between sentences; these space-counters would count an extra word per sentence. "Also, scenarios such as spaces around a hyphen - like that. "

For my purposes, this was far more accurate:

SELECT 
  LENGTH(REGEXP_REPLACE(myText, '[ \n\t\|\-]{1,}',' ')) - 
  LENGTH(REGEXP_REPLACE(myText, '[ \n\t\|\-]{1,}', '')) wordCount FROM myTable;

It counts any sets of 1 or more consecutive characters from any of: [ space , linefeed , tab , pipe , or hyphen ] and counts it as one word.