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Why Does My MySQL `NOT IN` Subquery with Multiple Columns Return 'Operand Should Contain 1 Column'?
Why Does My MySQL `NOT IN` Subquery with Multiple Columns Return 'Operand Should Contain 1 Column'?
Jan 12, 2025 am 09:48 AM
MySQL NOT IN "Operation should contain 1 column" error caused by multiple columns in subquery
It is common to encounter the "operand should contain 1 column" error when using the NOT IN clause of a subquery that contains multiple columns. This error arises from the restriction that the NOT IN clause expects the subquery to return only a single column.
In the query provided:
SELECT * from campaigns WHERE id not in
(
SELECT
e.id_campaign, d.name, d.frequency, d.country, d.referral, d.bid, d.status, COUNT(e.id) AS countcap
FROM campaigns d
LEFT JOIN served e
ON d.id = e.id_campaign
WHERE
d.status = 'Active'
GROUP BY e.id_campaign
HAVING
countcap < d.frequency
)
The subquery returns eight columns (id_campaign, name, frequency, country, referral, bid, status, and countcap). However, the NOT IN clause requires a single column for comparison.
Solution:
To fix this error, we need to modify the subquery so that it only returns the id_campaign column, which is the column we want to check for non-membership in the main query:
SELECT *
FROM campaigns
WHERE id NOT IN (
SELECT id_campaign
FROM (
SELECT e.id_campaign AS id_campaign, d.frequency, e.id
FROM campaigns d
LEFT JOIN served e ON d.id = e.id_campaign
WHERE d.status = 'Active'
GROUP BY e.id_campaign
HAVING COUNT(e.id) < d.frequency
) AS subquery
);
By limiting the subquery results to a single column id_campaign, we eliminate the "operand should contain 1 column" error and ensure that the NOT IN clause performs the comparison correctly. Note that we added an alias subquery to organize the query more clearly. This modified query will only return rows in the campaigns table where id is not in the subquery results.
The above is the detailed content of Why Does My MySQL `NOT IN` Subquery with Multiple Columns Return 'Operand Should Contain 1 Column'?. For more information, please follow other related articles on the PHP Chinese website!
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