![]() The following query return the data type of the items: SELECT json_typeof (info-> 'items') ![]() It can be number, boolean, null, object, array, and string. The json_typeof() function returns type of the outermost JSON value as a string. The following query returns all keys of the nested items object in the info column SELECT json_object_keys (info-> 'items')įROM orders Code language: SQL (Structured Query Language) ( sql ) json_typeof function To get a set of keys in the outermost JSON object, you use the json_object_keys() function. If you want to get a set of key-value pairs as text, you use the json_each_text() function instead. See the following statement: SELECT json_each (info) The json_each() function allows us to expand the outermost JSON object into a set of key-value pairs. PostgreSQL provides us with some functions to help you process JSON data. SUM ( CAST (info -> 'items' -> 'qty' AS INTEGER)),ĪVG ( CAST (info -> 'items' -> 'qty' AS INTEGER))įROM orders Code language: SQL (Structured Query Language) ( sql ) PostgreSQL JSON functions MAX ( CAST (info -> 'items' -> 'qty' AS INTEGER)), SELECT MIN ( CAST (info -> 'items' -> 'qty' AS INTEGER)), For example, the following statement returns minimum quantity, maximum quantity, average quantity and the total quantity of products sold. We can apply aggregate functions such as MIN, MAX, AVERAGE, SUM, etc., to JSON data. Notice that we used the type cast to convert the qty field into INTEGER type and compare it with two. WHERE CAST ( info -> 'items' -> 'qty' AS INTEGER) = 2 Code language: SQL (Structured Query Language) ( sql ) To find out who bought two products at a time, we use the following query: SELECT info -> 'customer' AS customer, ![]() WHERE info -> 'items' -> 'product' = 'Diaper' Code language: SQL (Structured Query Language) ( sql ) For example, to find out who bought Diaper, we use the following query: SELECT info -> 'customer' AS customer We can use the JSON operators in WHERE clause to filter the returning rows. And then info->'items'->'product' returns all products as text. ![]() ORDER BY product Code language: SQL (Structured Query Language) ( sql )įirst info -> 'items' returns items as JSON objects. For example, the following statement returns all products sold: SELECT info -> 'items' -> 'product' as product The following query uses the operator -> to get all customers in form of JSON: SELECT info -> 'customer' AS customerįROM orders Code language: SQL (Structured Query Language) ( sql )Īnd the following query uses operator -> to get all customers in form of text: SELECT info -> 'customer' AS customerīecause -> operator returns a JSON object, you can chain it with the operator -> to retrieve a specific node. The operator -> returns JSON object field by text.The operator -> returns JSON object field by key.PostgreSQL provides two native operators -> and -> to help you query JSON data. PostgreSQL returns a result set in the form of JSON. To query JSON data, you use the SELECT statement, which is similar to querying other native data types: SELECT info FROM orders Code language: SQL (Structured Query Language) ( sql ) VALUES( '') Ĭode language: SQL (Structured Query Language) ( sql ) Querying JSON data The following INSERT statement inserts a new row into the orders table. To insert data into a JSON column, you have to ensure that data is in a valid JSON format. The info column stores the data in the form of JSON.The id column is the primary key column that identifies the order.The orders table consists of two columns: ) Code language: SQL (Structured Query Language) ( sql ) Let’s get started by creating a new table for practicing with JSON data type. PostgreSQL supports native JSON data type since version 9.2. It provides many functions and operators for manipulating JSON data. Unlike other formats, JSON is human-readable text. The main usage of JSON is to transport data between a server and a web application. JSON is an open standard format that consists of key-value pairs. JSON stands for JavaScript Object Notation. Summary: in this tutorial, you will learn how to how to work with PostgreSQL JSON data type and some useful operators and functions for handling JSON data.
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