Reading JSON from MEMSQL - json

Question

Having a problem with JSON / MEMSQL. Here's my table:
CREATE TABLE `MEMSQLPOLYGLOT` (
ID BIGINT AUTO_INCREMENT,
`DATA` JSON NULL,
PRIMARY KEY (ID)
);
Here's the record I'm trying to read:
insert into MEMTEST (DATA) values
('
{
"EnterpriseMessage" :
{
"Body" :
[
{
"AccountNumber":"ABCD",
"AdminCompany":null,
"BrokerNumber":"WWonka"
},
{
"AccountNumber":"CSNE",
"AdminCompany":null,
"BrokerNumber":"ZWiza"
}
],
"Header" :
{
"mimetye":"application/vnd.ms-powerpoint",
"destinationsystem":"ETL",
"requiresack":"FALSE",
"SimpArr":
[
"BYTS6181",
"EVU98124",
"Genesys"
],
"EmptyFile":1
}
}
}
');
I can read the SimpArr array in the header.
SELECT DATA::EnterpriseMessage::Header::SimpArr from MEMTEST;
Returns:
["BYTS6181","EVU98124","Genesys"]
I can also pass in a key index to get a specific value, such as:
select JSON_EXTRACT_JSON(DATA::EnterpriseMessage::Body, 1) from MEMTEST;
This returns the 2nd value of the SimpArr since it's a zero-based index.
I can also read the array of objects in the Body:
select JSON_EXTRACT_JSON(DATA::EnterpriseMessage::Body, 0) from MEMTEST;
which returns the first object in that array:
{
"AccountNumber":"ABCD",
"AdminCompany":null,
"BrokerNumber":"WWonka"
}
However, I am unable to find a way to read the individual attributes of this object.
Anyone have any ideas?

Answer 1

You can just pass the key as an extra argument to JSON_EXTRACT_JSON:
mysql> select JSON_EXTRACT_JSON(DATA::EnterpriseMessage::Body, 0, "AccountNumber") from MEMTEST;
+----------------------------------------------------------------------+
| JSON_EXTRACT_JSON(DATA::EnterpriseMessage::Body, 0, "AccountNumber") |
+----------------------------------------------------------------------+
| "ABCD" |
+----------------------------------------------------------------------+
1 row in set (0.08 sec)
JSON_EXTRACT_JSON takes any number of arguments, either string keys or integer array indices. For example, we can unroll the :: syntax in your example above:
select JSON_EXTRACT_JSON(DATA, "EnterpriseMessage", "Body", 0, "AccountNumber") from MEMTEST;
Also note that the return value has double quotes in it. That's because you extract JSON, and the JSON representation of a string has double quotes. If you actually want to get the string, use JSON_EXTRACT_STRING:
mysql> select JSON_EXTRACT_STRING(DATA, "EnterpriseMessage", "Body", 0, "AccountNumber") from MEMTEST;
+----------------------------------------------------------------------------+
| JSON_EXTRACT_STRING(DATA, "EnterpriseMessage", "Body", 0, "AccountNumber") |
+----------------------------------------------------------------------------+
| ABCD |
+----------------------------------------------------------------------------+
1 row in set (0.07 sec)