How to Get the Distinct Keys From A Json Column In Oracle?

To get the distinct keys from a JSON column in Oracle, you can use the JSON_TABLE function along with the DISTINCT keyword. This function allows you to extract and query JSON data in a tabular format. By specifying the column containing the JSON data as input, you can retrieve the distinct keys present in the JSON structure. This can be useful for understanding the structure of the JSON data and identifying unique keys for further analysis or processing.

What tools can you use to extract distinct keys from a JSON column in Oracle?

In Oracle, you can use the following tools to extract distinct keys from a JSON column:

1. JSON_TABLE function: This function allows you to extract data from a JSON column and parse it into relational format. By using the COLUMN keyword with the JSON_TABLE function, you can extract distinct keys from a JSON column.

Example:

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SELECT DISTINCT jt.column_name
FROM your_table, JSON_TABLE(your_json_column, '$' COLUMNS(
  column_name PATH '$'
) jt;

1. JSON_EXISTS function: This function allows you to check if a JSON object contains a specific key. By using the DISTINCT keyword with the JSON_EXISTS function, you can extract distinct keys from a JSON column.

Example:

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SELECT DISTINCT JSON_OBJECT_KEYS(your_json_column)
FROM your_table;

1. PL/SQL procedures: You can also use PL/SQL procedures to extract distinct keys from a JSON column by iterating through the JSON object and storing the keys in a collection.

Example:

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DECLARE
  v_keys SYS.ODCIVARCHAR2LIST;
BEGIN
  FOR i IN (SELECT DISTINCT JSON_OBJECT_KEYS(your_json_column) AS keys
            FROM your_table)
  LOOP
    v_keys := v_keys MULTISET UNION i.keys;
  END LOOP;

  FOR i IN 1..v_keys.COUNT LOOP
    DBMS_OUTPUT.PUT_LINE(v_keys(i));
  END LOOP;
END;

How do you handle NULL keys when extracting distinct keys from a JSON column in Oracle?

When handling NULL keys when extracting distinct keys from a JSON column in Oracle, you can use the JSON_OBJECT_KEYS function and filter out any NULL keys using a CASE statement.

Here is an example of how you can handle NULL keys when extracting distinct keys from a JSON column in Oracle:

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SELECT DISTINCT key_name
FROM (
    SELECT 
        CASE
            WHEN key_value IS NULL THEN NULL
            ELSE TO_CHAR(key_value)
        END AS key_name
    FROM your_table,
         JSON_TABLE(your_json_column, '$[*]' COLUMNS (
             key_value PATH '$'
         ))
)
WHERE key_name IS NOT NULL;

In this query:

• your_table is the table containing the JSON column.
• your_json_column is the JSON column from which you want to extract distinct keys.
• key_value is the alias for the extracted key values.
• The CASE statement is used to handle NULL keys and convert them to a string value.
• The DISTINCT keyword is used to remove any duplicates in the result set.
• The WHERE clause is used to filter out any NULL keys from the result set.

What is the easiest way to obtain distinct keys from a JSON column in Oracle?

The easiest way to obtain distinct keys from a JSON column in Oracle is to use the "JSON_OBJECT_KEYS" function. This function takes a JSON object as input and returns a list of distinct keys in that object. Here is an example query that demonstrates how to use the "JSON_OBJECT_KEYS" function:

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SELECT DISTINCT key
FROM your_table,
JSON_OBJECT_KEYS(your_json_column);

Replace "your_table" with the name of your table and "your_json_column" with the name of your JSON column. This query will return a list of distinct keys in the JSON column of the specified table.

What is the best practice for maintaining key uniqueness in a JSON column in Oracle?

The best practice for maintaining key uniqueness in a JSON column in Oracle is to use a combination of database constraints and application logic.

1. Database Constraints: Use a Unique Constraint or Unique Index on the JSON column to ensure that each key within the JSON object is unique. This will prevent the insertion of duplicate keys in the JSON column.

Example:

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ALTER TABLE your_table
ADD CONSTRAINT ensure_unique_key_in_json
CHECK (JSON_EXISTS(your_json_column, '$.key_name' RETURNING NUMBER(1) PREDICATE
(code = 'TRUE')));

1. Application Logic: Implement validation checks in your application code to ensure that only unique keys are inserted into the JSON column. This can be done by checking the JSON object before inserting data and handling any duplicate key errors that may occur.

By combining database constraints and application logic, you can maintain key uniqueness in a JSON column in Oracle effectively.

What is the best method to extract unique keys from a JSON column in Oracle?

One of the best methods to extract unique keys from a JSON column in Oracle is by using the JSON_TABLE function. Here is an example of how you can use this function to extract unique keys from a JSON column:

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SELECT DISTINCT key
FROM your_table,
     JSON_TABLE(json_column, '$.*'
                COLUMNS (key PATH '$'
                        ) 
           )

In this example, replace your_table with the name of your table and json_column with the name of your JSON column. This query will extract all unique keys from the JSON column and return them in the result set.