Research on chain calling techniques of where method in Laravel

Chain calling skills of where method in Laravel

With the continuous development of PHP technology, Laravel, as an excellent PHP development framework, has always been favored by developers. respected. In Laravel, the where method is one of the commonly used database query methods. Complex query logic can be easily implemented by chaining the where method. In this article, we will explore the chain calling technique of where method in Laravel, and demonstrate its powerful functions through specific code examples.

1. Basic where method call

First, let us start with the most basic where method call. In Laravel, we can implement simple conditional filtering through the where method. For example, we have a database table named "users". If we want to query users who are older than 18 years old, we can write the code like this:

$users = DB::table('users')->where('age', '>', 18)->get();

In the above code, the where method accepts three parameters: field name, Compare symbols and values. By calling the where method in a chain, we can achieve combined filtering of multiple conditions.

2. Multi-condition joint query

Suppose we need to query users whose user name is "Jack" and whose age is greater than 18 years old. We can write the code like this:

$users = DB::table('users')
    ->where('name', 'Jack')
    ->where('age', '>', 18)
    ->get();

Pass By calling the where method in a chain, we can connect multiple conditions together to achieve joint query of conditions.

3. Use of OR conditions

Sometimes, we need to query the results that meet any condition. In Laravel, you can use the orWhere method to implement queries with OR conditions. For example, if we need to query users who are older than 18 years old or whose name is "Jack", we can implement it like this:

$users = DB::table('users')
    ->where('age', '>', 18)
    ->orWhere('name', 'Jack')
    ->get();

By using the orWhere method, we can implement the query logic of OR conditions.

4. Application of nested conditions

Sometimes, we need to implement complex query logic and need to use nested conditions. In Laravel, nested condition queries can be implemented through closure functions. For example, if we need to query users who are older than 18 years old and whose name is "Jack" or "Rose", we can write the code like this:

$users = DB::table('users')
    ->where(function ($query) {
        $query->where('age', '>', 18)
              ->where(function ($query) {
                  $query->where('name', 'Jack')
                        ->orWhere('name', 'Rose');
              });
    })
    ->get();

By using closure functions, more complex nested condition queries can be implemented.

5. Use whereIn and whereNotIn

In addition to the methods introduced above, Laravel also provides whereIn and whereNotIn methods to implement conditional queries in a collection. For example, if we need to query users whose ages are between [18, 20, 25], we can write the code like this:

$ages = [18, 20, 25];
$users = DB::table('users')
    ->whereIn('age', $ages)
    ->get();

Similarly, we can also use the whereNotIn method to implement conditional queries that are not in a certain collection. .

Conclusion

Through the introduction of this article, we have deeply discussed the chain calling technique of where method in Laravel, and demonstrated its powerful function through specific code examples. In actual development, reasonable use of chain calls of the where method can greatly improve development efficiency and code readability. I hope this article can help you when using the where method in Laravel.

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