![]() INSERT INTO test (data) VALUES ('') īased on the previous query, I defined the column data as json for this tutorial. For the sake of visibility, below is the query of the table schema I will use to show examples of how to query data from a JSON column. In this article, I’ll explain the different ways you can query data from a JSON column in PostgreSQL. ![]() To extract that description, I would use a scalar sub-query: select (select jsonbbuildobject ('description', t.descr -> 'content') from jsonbarrayelements (h.hoteldata -> 'description') as t (descr) where t.descr. This can bring some different notations in the way you fetch data from a JSON column. You will have to expand the array if you want to do that and apply the condition in the WHERE clause - see GMB's answer. Luckily, PostgreSQL allows defining column types as json and jsonb, which are two JSON (JavaScript Object Notation) data types that allow storing unstructured data in a relational database. JSON is a semi-structured data that is a widely adopted data interchangeable format and it is a lightweight and flexible data type. CREATE TABLE jsontest( serialno SERIAL PRIMARY KEY, name VARCHAR INSERT INTO jsontest(name, metadata) SELECT name, metadata->marksscored. ![]() Some further operators exist only for jsonb, as shown in Table 9.46. ![]() As a software engineer, it is common to store structured data in a relational database such as PostgreSQL, or unstructured data in a non-relational database such as Mongo DB. The field/element/path extraction operators return NULL, rather than failing, if the JSON input does not have the right structure to match the request for example if no such key or array element exists. ![]()
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