How to remove duplicate queries in thinkphp5

When using ThinkPHP5 for development, we often encounter situations where we need to query unique data in the database. This situation is very common in actual development work, for example, it is necessary to obtain all unique brands under a certain product category, etc. So how to remove duplicate queries in ThinkPHP5?

1. Use the SELECT DISTINCT keyword

In SQL statements, you can use the SELECT DISTINCT keyword to obtain unique data. In ThinkPHP5, when using the query() method of the \think\Db class to execute a SQL query statement, you can directly use the SELECT DISTINCT keyword in the query conditions, for example:

use \think\Db;

$data = Db::query('SELECT DISTINCT `brand` FROM `goods` WHERE `category_id` = 1');

In the above code, we use SELECT The DISTINCT keyword obtains all brands with category_id being 1 in the goods table, and assigns the query results to the $data variable.

2. Use the distinct() method

In addition to using the SELECT DISTINCT keyword in the SELECT statement, you can also use the distinct() method provided by ThinkPHP5 to implement deduplication queries. As shown below:

use \think\Db;

$data = Db::name('goods')
    ->where('category_id', 1)
    ->distinct(true)
    ->field('brand')
    ->select();

In the above code, we use the name() method of the Db class to specify the query data table, the where() method to specify the filtering conditions, and the distinct() method The deduplication query is enabled, the field() method is used to specify the query field, and finally the select() method is used to perform the query operation.

3. Use the group() method

In addition to using the SELECT DISTINCT keyword and the distinct() method, you can also use the group() method to implement deduplication queries. As shown below:

use \think\Db;

$data = Db::name('goods')
    ->where('category_id', 1)
    ->group('brand')
    ->select();

In the above code, we use the name() method of the Db class to specify the query data table, the where() method to specify the filtering conditions, and the group() method Grouping is performed, and finally the select() method is used to perform the query operation.

In actual development work, we need to choose the appropriate deduplication query method according to specific business needs to ensure the accuracy and efficiency of the query results.

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