mybatis-plus columnMap

MyBatis-Plus is a popular extension library for MyBatis, a Java-based ORM framework. In MyBatis-Plus, the `columnMap` refers to a dynamic SQL feature that allows you to generate column maps for queries.

When using MyBatis-Plus, you can use the `columnMap` method provided by the `QueryWrapper` class. This method returns a `java.util.HashMap` object that represents the column map.

Here's an example of how to use the `columnMap` method:

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import java.util.HashMap;
import java.util.Map;

public class Example {
    public static void main(String[] args) {
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();
        Map<String, Object> columnMap = new HashMap<>();
        columnMap.put("name", "John");
        columnMap.put("age", 25);
        queryWrapper.allEq(columnMap);

        // You can use the queryWrapper for further operations, such as selecting or updating records
        // ...
    }
}

In this example, the `columnMap` is used to set conditions for the `QueryWrapper`. The `allEq` method is used to add equal conditions for all key-value pairs in the `columnMap`.

By utilizing the `columnMap` feature, you can easily construct dynamic queries without explicitly specifying each condition.