![]() ![]() Keep in mind, JSON isn’t the only format available for this kind of work, but XML and YAML are probably the only other ones worth mentioning in the same breath. Yup, you got it! It’s nothing more than a standardized format the community uses to pass data around. So, we use JSON to store and exchange data? Have no fear, fellow Pythoneers and Pythonistas. Luckily, this is a pretty common task, and-as with most common tasks-Python makes it almost disgustingly easy. One way or another, you’re up to your neck in JSON, and you’ve got to Python your way out. Perhaps you’re gathering information through an API or storing your data in a document database. Chances are you’re here because you need to transport some data from here to there. Since its inception, JSON has quickly become the de facto standard for information exchange. Watch it together with the written tutorial to deepen your understanding: Working With JSON Data in Python The best choice for simplicity and efficiency, as well as ease of code development, is to store multi-valued attributes in a normalized manner.Watch Now This tutorial has a related video course created by the Real Python team. Mysql> select json_arrayagg(value) as document from json_meta cross join json_table(document, '$' columns (value varchar(10) path '$')) as j where value not in ('1-1-16', '1-1-17') Mysql> select j.* from json_meta cross join json_table(document, '$' columns (value varchar(10) path '$')) as j where value not in ('1-1-16', '1-1-17') ![]() JSON generally makes SQL queries harder, not easier, if you want to access individual elements of an array or fields of an object using SQL.ĭemo: mysql> select j.* from json_meta cross join json_table(document, '$' columns (value varchar(10) path '$')) as j This is all sounding more and more complex. If you upgrade to MySQL 8.0, you could use JSON_TABLE() to explode the array, filter out the elements you don't want, then implode them back into an array with JSON_ARRAYAGG(). Then you can eliminate array elements, re-marshal the array back into JSON and update the database. If you had three or more things to remove, you'd have to sort the paths yourself and build the query in the right order.Īnother solution is to fetch the whole document into an application where you have access to a JSON library to explode the elements into an array. Mysql> select json_remove(json_remove(document, as j from json_meta You can do it in two queries, one to get the paths and then pick which path to use at each nesting level: mysql> select json_unquote(json_search(document, 'one', '1-1-17')), JSON_UNQUOTE(JSON_SEARCH(document, 'one', '1-1-16') )īut this can't be done in a single query without knowing the order. If you can ensure you search for the items in the right order, you can nest them: SELECT JSON_REMOVE( That answer indicates that MySQL 5.6 doesn't have much JSON support I am wondering, since I'm using MySQL 5.7, is there a simpler solution possible? However, that question doesn't have an accepted answer, and the one answer there is very complex. each string with a comma before, a comma after, a comma both before and after).įinal note: I found another question with the exact same issue described here. I'm wondering if the best solution would just be to use a chained REPLACE() with all permutations of commas on each string (i.e. The query grows exponentially complex with each additional string that needs to be removed. JSON_UNQUOTE(JSON_SEARCH(JSON_REMOVE( document, You need to do this instead: UPDATE json_meta JSON_REMOVE() can accept multiple path arguments, but the problem is that when multiple paths are specified, the result of JSON_REMOVE() is passed sequentially left to right on each path, which makes it very difficult to use the result of JSON_SEARCH() for each passed path.įor example, this does not work, because the 2nd JSON_SEARCH will return the incorrect index for '1-1-17' after '1-1-16' has been removed: UPDATE json_meta I may need to remove "1-1-16" and "1-1-17" so I end up with: Īt other times, I may need to remove just one value, or several more, in one query. ![]() I need to remove a varying number of those strings from the array, by value, in one query.Įxample JSON: ![]() I have a MySQL 5.7 database with a JSON column containing an array of strings. ![]()
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