[SQL/코드카타] LEFT JOIN | NOT IN (서브쿼리)

1581. Customer Who Visited but Did Not Make Any Transactions table: Visits+-------------+---------+| Column Name | Type |+-------------+---------+| visit_id | int || customer_id | int |+-------------+---------+visit_id is the column with unique values for this table.This table contains information about the customers who visited the mall. Table: Transactions+----------------+-----..

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• · 2025. 10. 29.
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[SQL/코드카타] 문자열의 길이 세기

1683. Invalid Tweets Table: Tweets+----------------+---------+| Column Name | Type |+----------------+---------+| tweet_id | int || content | varchar |+----------------+---------+tweet_id is the primary key (column with unique values) for this table.content consists of alphanumeric characters, '!', or ' ' and no other special characters.This table contains all the tweets i..

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• · 2025. 10. 29.
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