How to create a JSON object in MySql with a boolea

问题:

I would like my MySql query to return a JSON object that looks as follows:

{"name": "Piotr", "likesMysql": true}

This seems to be working fine when I do:

SELECT json_object(
    'name', 'Piotr',
    'likesMysql', TRUE
)

However when I try to derive the likesMysql from an if expression I get 0 and 1 instead of false and true e.g.:

SELECT json_object(
    'name', 'Piotr',
    'likesMysql', if(4 MOD 2 = 0, TRUE, FALSE)
)

results in

{"name": "Piotr", "likesMysql": 1}

How do I use the json_object to construct a JSON object that has true or false as property value?

回答1:

This seems to be a bug in MySql.

You can workaround it though with cast(true as json) e.g.:

SELECT json_object(
    'name', 'Piotr',
    'likesMysql', if(4 MOD 2 = 0, cast(TRUE as json), cast(FALSE as json))
)

回答2:

Simply go with following,

SELECT json_object( 'name', 'Piotr', 'likesMysql', if(5 MOD 2 = 0, TRUE, FALSE) is true )

Hope you get desired result with this :)

回答3:

Aniket Bhansali's approach could be simplified as:

select json_object(
    'bool_true', (4 mod 2 = 0) is true,
    'bool_false', 0 is true) b;

which returns

{"bool_true": true, "bool_false": false}

Tested on mysql 8.