Converting a mysql dict column using JSON_Table - mysql

Question

Edited
I have a mysql table "prop" with a column "detail" that contains a dict field.
fnum details
55 '{"a":"3"},{"b":"2"},{"d":"1"}'
I have tried to convert this to a table. using this
SELECT p.fnum, deets.*
FROM prop p
JOIN JSON_TABLE( p.details,
'$[*]'
COLUMNS (
idx FOR ORDINALITY,
a varChar(10) PATH '$.a',
b varchar(20) PATH '$.b'
d varchar(45) PATH '$.d',
)
) deets
I have tried various paths including $.*. I am expecting the following:
fnum a b d
55 3 2 1
also if I have 2 rows such as
fnum details
55 '{"a":"3"},{"b":"2"},{"d":"1"}'
56 '{"c":"car"}'
should generate the following
fnum a b d c
55 3 2 1 null
56 null null null car

Answer 1

Your details data is not valid JSON, because it doesn't have [ ] delimiting the array.
Demo:
mysql> create table prop (fnum int, details json);
mysql> insert into prop select 55, '{"a":"3"},{"b":"2"},{"d":"1"}';
ERROR 3140 (22032): Invalid JSON text: "The document root must
not be followed by other values." at position 9 in value for column
'prop.details'.
mysql> insert into prop select 55, '[{"a":"3"},{"b":"2"},{"d":"1"}]';
Query OK, 1 row affected (0.00 sec)
Records: 1 Duplicates: 0 Warnings: 0
It's worth using the JSON data type instead of storing JSON in a text column, because the JSON data type ensures that the document is valid JSON format. It must be valid JSON to use the JSON_TABLE() function or any other JSON function.
Also your query has some syntax mistakes with respect to commas:
SELECT p.fnum, deets.*
FROM prop p
JOIN JSON_TABLE( p.details,
'$[*]'
COLUMNS (
idx FOR ORDINALITY,
a varChar(10) PATH '$.a',
b varchar(20) PATH '$.b' <-- missing comma
d varchar(45) PATH '$.d', <-- extra comma
)
) deets