mybatisplus apply

MyBatis Plus is a powerful extension library for MyBatis, a popular Java-based persistence framework. It provides additional features and utilities to simplify and enhance the usage of MyBatis. One of its core features is the "apply" method, which allows you to dynamically apply query conditions to a SQL statement.

The "apply" method in MyBatis Plus is typically used in combination with the "Wrapper" interface. The "Wrapper" interface provides a set of methods for building query conditions, such as "eq" (equal), "like", "in", etc. By using the "apply" method, you can dynamically apply these query conditions to your SQL statement based on certain conditions.

Here's an example of how to use the "apply" method in MyBatis Plus:

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.toolkit.Wrappers;

public class MyBatisPlusExample {
    public List<User> getUsers(String name, Integer age) {
        QueryWrapper<User> queryWrapper = Wrappers.query();
        
        queryWrapper.eq("status", 1)
                    .like(StringUtils.isNotBlank(name), "name", name)
                    .lt(age != null, "age", age);
        
        // Apply the query conditions to the SQL statement
        queryWrapper.apply("date_format(create_time, '%Y-%m-%d') = {0}", "2022-01-01");
        
        return userDao.selectList(queryWrapper);
    }
}

In the above example, we create a `QueryWrapper` object and use various methods to build our query conditions. We then use the `apply` method to dynamically apply the additional condition `date_format(create_time, '%Y-%m-%d') = '2022-01-01'` to the SQL statement.

By using the `apply` method, you can easily add custom conditions to your SQL statements based on dynamic requirements. This can be particularly useful when you need to apply complex conditions that cannot be easily expressed using the provided query methods in MyBatis Plus.