mysql query exact match on json field not working - mysql

Question

table looks like this:
my_table
id (int) create_time (timestamp) meta_data (json)
1 2019-01-20 18:35:42 {"my property": "123"}
2 2019-01-20 19:35:42 {"more data": "456"}
I've tried querying with:
SELECT * FROM my_table
WHERE meta_data = '{"my property": "123"}';
SELECT * FROM my_table
WHERE meta_data = '\{\"my property\"\: \"123\"\}';
And it doesn't work, how can I query an exact match on a json field string?
I noticed this DOES work...
SELECT * FROM my_table
WHERE meta_data LIKE '\{\"my property\"\: \"123\"\}';
Do I need to use LIKE? Why = not work?

Answer 1

I know the JSON field is a special field type that is designed to let you easily query specific properties, but I wanted to be able to just check against the full JSON easily. And clearly the JSON field has some parameters that cause the = not to work as I expected.
This is the solution I figured out, cast JSON as CHAR:
SELECT * FROM my_table
WHERE CAST(meta_data as CHAR) = '{"my property": "123"}';
Another option:
SELECT * FROM my_table
WHERE meta_data = CAST('{"my property": "123"}' AS JSON);
You can also obtain JSON values by casting values of other types to the JSON type using CAST(value AS JSON);"
https://dev.mysql.com/doc/refman/5.7/en/json-creation-functions.html#function_json-quote

Answer 2

Use JSON_CONTAINS:
SELECT *
FROM my_table
WHERE JSON_CONTAINS(meta_data, '"123"', '.$"my property"');
Demo
Notes:
Since the target value to match for the key my property is a literal string, we need to also search for the double quotes.
To escape the key my property in the JSON path, we can escape that using double quotes.

Answer 3

If you want to compare a JSON column to a JSON value, then use JSON_OBJECT() to create the value.
Demo:
create table t (id int primary key, data json);
insert into t values (1, json_object('my property', '123'));
insert into t values (2, json_object('more_data', 456));
select * from t where data = json_object('more_data', 456);
+----+--------------------+
| id | data |
+----+--------------------+
| 2 | {"more_data": 456} |
+----+--------------------+

Answer 4

You should refer this
https://dev.mysql.com/doc/refman/5.7/en/json-search-functions.html
to use JSON data for query

Answer 5

Try (modify according to the right name of the property and datatype. If String use "123".
SELECT * FROM my_table WHERE JSON_EXTRACT(meta_data, "$.`my property`")= 123
Or may be
SELECT * FROM my_table WHERE JSON_EXTRACT(meta_data, "$.my property")= 123