![]() ![]() Because of SQL/JSON path-expression syntax relaxation. ![]() Note that if path expression $. were used in Example 16-1 it would give the same result. For the document in Example 4-2 the phone types are "Office" and "Mobile", and the array returned is either or. For each document it returns a VARCHAR2 value whose contents represent a JSON array with elements the phone types, in an unspecified order. The error clause for json_query can specify EMPTY ON ERROR, which means that an empty array ( ) is returned in case of error (no error is raised).Įxample 16-1 shows an example of the use of SQL/JSON function json_query with an array wrapper. The wrapper clause determines the form of the returned string value. It is commonly used for transmitting data in web applications (e.g., sending some data from the server to the client, so it can be displayed on a web page, or vice versa). In the RETURNING clause you can specify only data type VARCHAR2 you cannot specify NUMBER. Overview: Objects Next JavaScript Object Notation (JSON) is a standard text-based format for representing structured data based on JavaScript object syntax. The path expression can target any number of JSON values. The second argument to json_query is a SQL/JSON path expression followed by optional clauses RETURNING, WRAPPER, ON ERROR, and ON EMPTY. ![]() The result of evaluating the SQL expression is used as the context item for evaluating the path expression. Youll see hands-on examples of working with Pythons built-in json. The two structural constructs of JSON are objects and arrays. In this tutorial youll learn how to read and write JSON-encoded data using Python. In common with XPath, this will select all possible values in the document that match the specified location path. It can be a table or view column value, a PL/SQL variable, or a bind variable with proper casting. Simple Queries To support the extraction of values from a JSON structure, a location path syntax is defined. It can be of data type VARCHAR2, BLOB, or CLOB. The first argument to json_query is a SQL expression that returns an instance of a scalar SQL data type (that is, not an object or collection data type). ![]()
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