I have a table in MySQL where each row contains JSON returned from another system. The JSON will look something like:
[{"userId": "Dave"},{"userId": "Mary", "errorCode" : "DB Fail"}, {"userId": "Lorenza", "errorCode": "Web Error"}]
and I'm only interested in the members of the array containing an error code. In the future, these will be parsed into seperate rows of their own table, but in the meantime does MySql offer a way to extract only these with an errorCode?
I can use JSON_EXTRACT to extract the errorCodes only
JSON_EXTRACT(jsonData, '$[*].errorCode') AS errorCodes
but I really want the rest of the member (userId in the example above)
You could use the JSON_CONTAINS function to find the records with errorCode and then then use JSON_EXTRACT on those records. Put the JSON_CONTAINS in the where clause
I don't think you could do this with a single query without known boundaries of the number of elements, but you could use a stored procedure to run a loop.
e.g. each iteration runs LOCATE to find the position of "errorCode", and uses that location to run SUBSTR and/or SUBSTRING_INDEX to get the userid value and append it to another variable. The looped variable would just be the offset used in the LOCATE query.
Related
When I want to take data from mysql in NodeJS, it results like
RowDataPacket { name : 'John', marks : 56}
But I want to take this data without column names or other things. I need to use just NodeJS for this problem. I saw some JSON solutions but I can’t do this cause of my program.
The result of a 'SELECT' query will be an array of objects. And each object defines a row.
You can either iterate through the array and use the key to access its value like results.forEach( row => { row[key] })
or if your result returns a single row, then you can access the object as results[0].
You need to set an index and then obtain the value.
For example if you are storing your response in a variable called results.
Use the following:
x = results[0].name;
Then you can use this variable/name further in your program.
i have a code in sql for string comparison which takes two parameters as input works upon it and returns a result. both of the parameters are words, i want to change the parameter from a single word to a database column. how do i do that?
say for example in java its like storing the data in an array and than passing the whole array. can something like this be done in sql?
You can use the Select query for passing each value of a particular column from the table into your function.
like this,
SELECT compare_city_name('baroda',t.cityname) from tablename as t
In this query, you pass all cities name from cityname column to the function compare_city_name one by one.
Pass it as a VARCHAR, then build the query with "prepare" and "execute" it.
I have an JSON string stored in the database and I need to SQL COUNT based on the WHERE condition that is in the JSON string. I need it to work on the MYSQL 5.5.
The only solution that I found and could work is to use the REGEXP function in the SQL query.
Here is my JSON string stored in the custom_data column:
{"language_display":["1","2","3"],"quantity":1500,"meta_display:":["1","2","3"]}
https://regex101.com/r/G8gfzj/1
I now need to create a SQL sentence:
SELECT COUNT(..) WHERE custom_data REGEXP '[HELP_HERE]'
The condition that I look for is that the language_display has to be either 1, 2 or 3... or whatever value I will define when I create the SQL sentence.
So far I came here with the REGEX expression, but it does not work:
(?:\"language_display\":\[(?:"1")\])
Where 1 is replaced with the value that I look for. I could in general look also for "1" (with quotes), but it will also be found in the meta_display array, that will have different values.
I am not good with REGEX! Any suggestions?
I used the following regex to get matches on your test string
\"language_display\":\[(:?\"[0-9]\"\,)*?\"3\"(:?\,\"[0-9]\")*?\]
https://regex101.com/ is a free online regex tester, it seems to work great. Start small and work big.
Sorry it doesn't work for you. It must be failing on the non greedy '*?' perhaps try without the '?'
Have a look at how to serialize this data, with an eye to serializing the language display fields.
How to store a list in a column of a database table
Even if you were to get your idea working it will be slow as fvck. Better off to process through each row once and generate something more easily searched via sql. Even a field containing the comma separated list would be better.
I am creating a query to re-use periodically to pull data out of a MySQL database (not for use in production code) and want to display values from a JSON object as columns. I installed common_schema and have been using the extract_json function but I can't find the correct xpath to use to get the field I want, I always get null. The query I am using currently is below:
SELECT common_schema.extract_json_value(stores.info,'/Region') as "Sales Region" FROM stores
An example of the JSON object stored in stores.info is below:
{"Town":"HDM","Post Code":"003408","Region":"FGH","OutletCode":"AB43G","CustomerCode":"15134158"}
What xpath do I need to access, for example Region. If the path is correct why is it returning NULL?
I don't know if there is a better description of my problem, but here is what I need help with:
I have a field with lots of data, and the part I need to solve looks like this:
::field_x::<br />||field_x||519||/field_x||<br />||field_x||281||/field_x||<br />::/field_x::
I have to extract each number (id) from this, 519 and 281 in this example, and insert them in a field in another table, separated by spaces or commas. I know how to use SUBSTRING - LOCATE method, but that would return only the first instance, so is there a method to extract them all in one go?
SUBSTRING INDEX LOCATE will work. There is no built in functionality for regular expressions so unless you handle it before it gets to mysql...you're stuck using the SUBSTRING INDEX LOCATE method...
If you need to iterate through a dataset, you will need to initiate a cursor, or FOR loop and use a stored proc.
parse results in MySQL via REGEX