sql 连接两个 table 的查询和一个布尔标志以指示它是否包含来自第三个 table 的任何单词

Question

我有 3 个 table 具有以下架构

create table main (
  main_id int PRIMARY KEY,
  secondary_id int NOT NULL
);

create table secondary (
  secondary_id int NOT NULL,
  tags varchar(100)
);

create table bad_words (
  words varchar(100) NOT NULL
);

insert into main values (1, 1001);
insert into main values (2, 1002);
insert into main values (3, 1003);
insert into main values (4, 1004);

insert into secondary values (1001, 'good word');
insert into secondary values (1002, 'bad word');
insert into secondary values (1002, 'good word');
insert into secondary values (1002, 'other word');
insert into secondary values (1003, 'ugly');
insert into secondary values (1003, 'bad word');
insert into secondary values (1004, 'pleasant');
insert into secondary values (1004, 'nice');

insert into bad_words values ('bad word');
insert into bad_words values ('ugly');
insert into bad_words values ('worst');

expected output
----------------
1, 1000, good word, 0 (boolean flag indicating whether the tags contain any one of the  words from the bad_words table)
2, 1001, bad word,good word,other word , 1
3, 1002, ugly,bad word, 1
4, 1003, pleasant,nice, 0

我正在尝试使用 case to select 1 或 0 作为最后一列，并使用联接来联接主要和次要 table，但感到困惑和卡住。有人可以帮我查询吗？这些 table 存储在 redshift 中，我希望查询与 redshift 兼容。

您可以使用上述架构在 sqlfiddle

中尝试您的查询

编辑：我现在通过删除辅助 table 中的 PRIMARY KEY 更新了模式和预期输出，以便更容易加入 bad_words table。

Answer 1

select main_id, a.secondary_id, tags, case when c.words is not null then 1 else 0 end from main a join secondary b on b.secondary_id = a.secondary_id left outer join bad_words c on c.words like b.tags

Answer 2

您可以使用 EXISTS 和正则表达式比较 \m 和 \M（分别表示单词的开头和结尾的标记）：

with
  main(main_id, secondary_id) as (values (1, 1000), (2, 1001),  (3, 1002), (4, 1003)),
  secondary(secondary_id, tags) as (values (1000, 'very good words'), (1001, 'good and bad words'), (1002, 'ugly'),(1003, 'pleasant')),
  bad_words(words) as (values ('bad'), ('ugly'), ('worst'))

select *, exists (select 1 from bad_words where s.tags ~* ('\m'||words||'\M'))::int as flag
from main m
join secondary s using (secondary_id)

Answer 3

SELECT m.main_id, m.secondary_id, t.tags, t.is_bad_word
FROM srini.main m
JOIN (
    SELECT st.secondary_id, st.tags, exists (select 1 from srini.bad_words b where st.tags like '%'+b.words+'%') is_bad_word
    FROM 
    ( SELECT secondary_id, LISTAGG(tags, ',') as tags
      FROM srini.secondary
      GROUP BY secondary_id ) st
) t on t.secondary_id = m.secondary_id;

这在 redshift 中对我有用，并使用上述模式生成了以下输出。

1   1001    good word   false
3   1003    ugly,bad word   true
2   1002    good word,other word,bad word   true
4   1004    pleasant,nice   false

sql 连接两个 table 的查询和一个布尔标志以指示它是否包含来自第三个 table 的任何单词

sql query to join two tables and a boolean flag to indicate whether it contains any words from third table

sql

postgresql

join

amazon-redshift