如果数据库golang mysql中的字段为空，则处理结果

Question

the result wantedI have a struct in go

type Users struct {
    ID    int    `json:"id"`
    Name  string `json:"name"`
    Age   string `json:"age"`
}

I have a mysql database in which some age values are nil so basically to make it dynamic I've been searching for the solution. "Age string json:-" to hide the field if it is returnig the value nil from mysql. I did two queries

   query1: select id,name,age from users where age is not null
   query2: select id,name from users where age is null

How can I make it a dynamic query to show the age if exsits else it doesn't don't show it?

Answer 1

Don't do that. Instead, use a nil-able type for your Age field. *string or sql.NullString would be the most natural choices. Then just always select it, and the NULL value will be treated properly.

type Users struct {
    ID    int     `json:"id"`
    Name  string  `json:"name"`
    Age   *string `json:"age"`
}

Then always use:

SELECT id, name, age FROM users

And when Age is NULL in the database, it will be nil in Go, and when it's not NULL in the database, it will be a non-nil pointer to a string in Go.