Syntax

Description of the illustration json_array.eps

JSON_on_null_clause::=

Description of the illustration json_on_null_clause.eps

JSON_returning_clause::=

Description of the illustration json_returning_clause.eps

Purpose

The SQL/JSON function JSON_ARRAY takes as its input one or more SQL expressions, converts each expression to a JSON value, and returns a JSON array that contains those JSON values.

expr

For expr, you can specify any SQL expression that evaluates to a JSON object, a JSON array, a numeric literal, a text literal, date, timestamp, or null. This function converts a numeric literal to a JSON number value, and a text literal to a JSON string value. The date and timestamp data types are printed in the generated JSON object or array as JSON Strings following the ISO 8601 date format.

FORMAT JSON

This clause is optional and is provided for semantic clarity.

JSON_on_null_clause

Use this clause to specify the behavior of this function when expr evaluates to null.

• NULL ON NULL - If you specify this clause, then the function returns the JSON null value.

• ABSENT ON NULL - If you specify this clause, then the function omits the value from the JSON array. This is the default.

JSON_returning_clause

The character string returned by this function is of data type VARCHAR2. This clause allows you to specify the size of the VARCHAR2 data type. Use BYTE to specify the size as a number of bytes or CHAR to specify the size as a number of characters. The default is BYTE. If you omit this clause, or if you specify this clause but omit the size value, then JSON_ARRAY returns a character string of type VARCHAR2(4000).

Refer to VARCHAR2 Data Type for more information. Note that when specifying the VARCHAR2 data type elsewhere in SQL, you are required to specify a size. However, in the JSON_returning_clause you can omit the size.

Examples

The following example constructs a JSON array from a JSON object, a JSON array, a numeric literal, a text literal, and null:

SELECT JSON_ARRAY (     
    JSON_OBJECT('percentage' VALUE .50),
    JSON_ARRAY(1,2,3),
    100,
    'California',
    null
    NULL ON NULL
    ) "JSON Array Example"
  FROM DUAL;
 
JSON Array Example
--------------------------------------------------------------------------------
[{"percentage":0.5},[1,2,3],100,"California",null]