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.
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