Bug: [QueryBuilder] if set limit to 0, it will return all data. Perhaps it should return 0 data. #8278

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1. RikhzanAmir

   added

   bugVerified issues on the current code behavior or pull requests that will fix themVerified issues on the current code behavior or pull requests that will fix them

   on Nov 30, 2023
2. kenjis commented on Nov 30, 2023

   

   kenjis

   on Nov 30, 2023

   Last edited by kenjis

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   Thank you for reporting. This is very interesting.

   $builder->limit(10, 20);
   // Produces: LIMIT 20, 10 (in MySQL. Other databases have slightly different syntax)
   https://codeigniter4.github.io/CodeIgniter4/database/query_builder.html#limit

   As I read it, I expect limit(0, 0) produces LIMIT 0, 0.
   In reality, however, no LIMIT clause is generated.
3. lonnieezell commented on Nov 30, 2023

   

   lonnieezell

   on Nov 30, 2023

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   What is the practical purpose of doing a query where you don't want any results? I'm not sure that I can think of a reason to do that.

   Think of it as "there's 0 limit on the number of results I'd like returned."
4. kenjis commented on Nov 30, 2023

   

   kenjis

   on Nov 30, 2023

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   This behavior has not changed since the beginning of 4.0.
   

   CodeIgniter4/system/Database/BuilderTrait.php

   Lines 2400 to 2404 in 4d2746f

   	// LIMIT
   	if ($this->QBLimit)
   	{
   	return $this->_limit($sql."\n");
   	}
5. kenjis commented on Nov 30, 2023

   

   kenjis

   on Nov 30, 2023

   Last edited by kenjis

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   In CI3, the following code generates SELECT * FROM "job" LIMIT 0 (sqlite3):

   		$jobs = $this->db->limit(0, 0)
   		                      ->get('job')
   		                      ->result_array();

   		// LIMIT
   		if ($this->qb_limit !== FALSE OR $this->qb_offset)
   		{
   			return $this->_limit($sql."\n");
   		}

   https://github.com/bcit-ci/CodeIgniter/blob/63d037565dd782795021dcbd3b1ca6f8c8a509e4/system/database/DB_query_builder.php#L2440-L2444
6. kenjis

   changed the title [-]Bug: Query limit, if set limit => 0 , it will return all data. Perhaps it should return 0 data.[/-] [+]Bug: [QueryBuilder] if set limit to 0, it will return all data. Perhaps it should return 0 data.[/+] on Nov 30, 2023
7. kenjis commented on Nov 30, 2023

   

   kenjis

   on Nov 30, 2023

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   I don't know if this is a bug or not.

   Since no one has reported it before, there are probably few use cases where 0 is specified.
8. RikhzanAmir commented on Nov 30, 2023

   

   RikhzanAmir

   on Nov 30, 2023

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   I am writing this query in MariaDB: "SELECT * FROM payment limit 0 offset 0" , and it shows no result.

   So on Ci3, and Ci4 I am expecting $builder->limit(0,0) or $builder->limit($set, $offset) do the same.

   Maybe, it is not a bug, some query do different depending on database we use.

   https://dev.mysql.com/doc/refman/8.0/en/limit-optimization.html

   "LIMIT 0 quickly returns an empty set. This can be useful for checking the validity of a query. It can also be employed to obtain the types of the result columns within applications that use a MySQL API that makes result set metadata available."
9. kenjis commented on Nov 30, 2023

   

   kenjis

   on Nov 30, 2023

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   Do you have a use case for limit 0 with Query Builder?

   LIMIT is not in SQL standards. So we don't need to implement like MySQL's.
   But since "limit 1" returns 1 row, it is logical that "limit 0" would return 0 rows.
   However, the implementation will be more complicated than it is now.

   👍React with 👍1Reacted by RikhzanAmir
10. RikhzanAmir commented on Nov 30, 2023

    

    RikhzanAmir

    on Nov 30, 2023

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    If that so, maybe do not change and stick to it. Because on my side it can be fix by adding 1 line of code.

    $query = $this->db->table('order')->limit($quantity)->offset($offset)->get()->getResultArray();
    return empty($quantity) ? [] : $query;
    
11. kenjis commented on Nov 30, 2023

    

    kenjis

    on Nov 30, 2023

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    if ($quantity === 0) {
        return [];
    }
    $query = $this->db->table('order')->limit($quantity)->offset($offset)->get()->getResultArray();
12. kenjis commented on Dec 1, 2023

    

    kenjis

    on Dec 1, 2023

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    I sent PR #8280 to fix this.
13. RikhzanAmir

    closed this as completedon Dec 1, 2023
14. kenjis

    reopened this on Dec 1, 2023
15. kenjis commented on Dec 20, 2023

    

    kenjis

    on Dec 20, 2023

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    You can fix this behavior in v4.5.0. See #8280
16. kenjis

    closed this as completedon Dec 20, 2023