mysql - 使用 SQL 计算字符串和 Group By 中字符的出现次数

Question

我尝试计算出现次数并在之后添加分组依据，但出现错误

SELECT list is not in GROUP BY clause and contains nonaggregated column ‘bdd.my_table.text' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

我的 table :

id | book | chapter | text
 1 |   1  |    1    | 'hello hello world'
 2 |   1  |    2    | 'hello hello hello hello'
 3 |   1  |    3    | 'world'
 4 |   1  |    4    | 'hello test'

我执行我的请求:

SELECT 
    book,
    chapter,
    text,    
    ROUND (   
        (
            LENGTH(text)
            - LENGTH( REPLACE ( text, "hello", "") ) 
        ) / LENGTH("hello")        
    ) AS count    
FROM my_table
WHERE book=43
GROUP BY chapter

我想要这个结果:

book | chapter | count
----------------------
  43  |    1    |   2
  43  |    2    |   4
  43  |    3    |   0
  43  |    4    |   1

我尝试在删除“only_full_group_by”的请求之前添加此内容，但我遇到了同样的问题

SET SESSION group_concat_max_len = 1000000;

Answer 1

试试这个，虽然我到现在还不知道你到底想做什么，但是试试吧。

SELECT
    book,
    chapter,
    group_concat(text) as text,    
    ROUND (   
        (
            LENGTH(group_concat(text))
            - LENGTH( REPLACE ( group_concat(text), "hello", "") ) 
        ) / LENGTH("hello")        
    ) AS `count`
FROM my_table
GROUP BY chapter, book