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How to Perform SQL JSON Query

How to Perform SQL JSON Query

If you want to query JSON data using SQL, the good news is that SQL Server has built-in support for JSON. In this tutorial, you will learn how to perform SQL JSON query.

What is JSON?

JSON stands for JavaScript Object Notation. It is a lightweight data-interchange format that is easy for humans to read and write and easy for machines to parse and generate. JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others.

What is SQL JSON Query?

SQL JSON query is a way to query JSON data using SQL. In SQL Server, you can use the JSON_VALUE, JSON_QUERY, and JSON_MODIFY functions to query and modify JSON data.

How to Perform SQL JSON Query?

To perform SQL JSON query, you need to follow these steps:

  1. Create a table with a JSON column
  2. Insert JSON data into the table
  3. Query JSON data using JSON_VALUE, JSON_QUERY, and JSON_MODIFY functions

Step 1: Create a table with a JSON column

To create a table with a JSON column, you can use the following SQL statement:

CREATE TABLE my_table (
   id INT PRIMARY KEY,
   data NVARCHAR(MAX) NOT NULL
)

The data column is of type NVARCHAR(MAX), which can store up to 2GB of Unicode characters. This column will hold the JSON data.

Step 2: Insert JSON data into the table

To insert JSON data into the table, you can use the following SQL statement:

INSERT INTO my_table (id, data)
VALUES (1, '{"name": "John Doe", "age": 30, "city": "New York"}')

This statement will insert a row into the my_table table with the JSON data in the data column.

Step 3: Query JSON data using JSON_VALUE, JSON_QUERY, and JSON_MODIFY functions

To query JSON data using JSON_VALUE, JSON_QUERY, and JSON_MODIFY functions, you can use the following SQL statements:

JSON_VALUE function

The JSON_VALUE function returns a scalar value from a JSON string.

SELECT JSON_VALUE(data, '$.name') as name
FROM my_table

This statement will return the name value from the JSON data in the data column.

name
John Doe

JSON_QUERY function

The JSON_QUERY function returns a JSON fragment from a JSON string.

SELECT JSON_QUERY(data, '$.age') as age
FROM my_table

This statement will return the age value from the JSON data in the data column.

age
30

JSON_MODIFY function

The JSON_MODIFY function modifies a JSON string.

UPDATE my_table
SET data = JSON_MODIFY(data, '$.city', 'Los Angeles')
WHERE id = 1

This statement will update the city value from New York to Los Angeles in the JSON data in the data column.

Troubleshooting tips

  • Make sure that you are using valid JSON format
  • Make sure that your JSON path is correct
  • Make sure that your JSON path matches the JSON structure

Conclusion

In conclusion, SQL JSON query is a powerful feature that allows you to query and modify JSON data using SQL Server. With the JSON_VALUE, JSON_QUERY, and JSON_MODIFY functions, you can easily extract and manipulate JSON data in your SQL queries.

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