AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |
Back to Blog
Mysql json query example1/30/2024 | 11:55:12 | High-Performance Java Persistence 1st edition | Vlad Mihalcea | 4499 | Amazon | | 11:55:11 | High-Performance Java Persistence 1st edition | Vlad Mihalcea | 3990 | Amazon | | version_timestamp | title | author | price_in_cents | publisher | When running the above SQL query, we get the following result set: Publisher VARCHAR(255) PATH '$.publisher' Price_in_cents INT(11) PATH '$.price_in_cents', Luckily, MySQL provides us the JSON_TABLE function, which we can use to transform a JSON object to a relational database table, as illustrated by the following SQL query:īook_audit_log.dml_timestamp as version_timestamp, Instead, we’d like to recreate the book table structure associated with a new_row_data entry. For this, we can use the new_row_data JSON column, but we don’t want to return the results in JSON format. Now, we want to extract all versions of a given book entity. Transforming a JSON object to a relational table with the MySQL JSON_TABLE function | book_id | old_row_data | new_row_data | dml_type | dml_timestamp | dml_created_by | Let’s assume that the book_audit_log table contains the following data: The book table stores all the books we have in our library, and the book_audit_log table stores the CDC (Change Data Capture) events that were generated whenever a given book record was changed via an INSERT, UPDATE, or DELETE SQL statement. We are going to reuse the same database tables we used when implementing an audit log table using MySQL triggers and JSON columns: Thanks to the JSON column approach, we can even use a single audit log table for all target tables that we are auditing. However, there are certain use cases when the relational model is too strict, and we are better off storing data in a JSON column type.įor instance, as I explained in this article, when designing an audit log table, it’s much more convenient to store the before and after row snapshots in JSON columns, as this strategy will accommodate future target table modifications while also avoiding to duplicate every target table column in the audit log table. When using a relational database system, it’s best to design the database schema according to the relational model. In this article, I’m going to explain how the MySQL JSON_TABLE function works, and how you can use it to transform a JSON object into a relational database table. So, enjoy spending your time on the things you love rather than fixing performance issues in your production system on a Saturday night! Well, Hypersistence Optimizer is that tool!Īnd it works with Spring Boot, Spring Framework, Jakarta EE, Java EE, Quarkus, or Play Framework. Use the JSON_TYPE() function to get the type of a JSON value.Follow having a tool that can automatically detect JPA and Hibernate performance issues.JSON_TYPE( 'null') type Code language: SQL (Structured Query Language) ( sql )ġ row in set ( 0.00 sec) Code language: SQL (Structured Query Language) ( sql ) Summary JSON_TYPE( 'true') type Code language: SQL (Structured Query Language) ( sql )ġ row in set ( 0.00 sec) Code language: SQL (Structured Query Language) ( sql ) 6) Getting the type of NULL SELECT JSON_TYPE( '1.0') type Code language: SQL (Structured Query Language) ( sql )ġ row in set ( 0.00 sec) Code language: SQL (Structured Query Language) ( sql ) 5) Getting the type of a boolean SELECT JSON_TYPE( '"Hello"') type Code language: SQL (Structured Query Language) ( sql )ġ row in set ( 0.00 sec) Code language: SQL (Structured Query Language) ( sql ) 4) Getting the type of a number SELECT JSON_TYPE( '') type Code language: SQL (Structured Query Language) ( sql )ġ row in set ( 0.01 sec) Code language: SQL (Structured Query Language) ( sql ) 2) Getting the type of an array SELECTġ row in set ( 0.00 sec) Code language: SQL (Structured Query Language) ( sql ) 3) Getting the type of a string SELECT Let’s take some examples of using the JSON_TYPE() function. If the value is not a valid JSON value, the function raises an error. If the value is NULL, the JSON_TYPE() function returns NULL. The JSON_TYPE() function returns a string that represents the JSON type of the value. value: This is the JSON value that you want to get the type, which can be an object, an array, or a scalar type (integer, boolean, null, etc).Here’s the syntax of the JSON_TYPE function: JSON_TYPE(value) Code language: SQL (Structured Query Language) ( sql ) The JSON_TYPE() function is used to return the data type of a JSON value. Introduction to MySQL JSON_TYPE() function Summary: in this tutorial, you will learn how to use the MySQL JSON_TYPE() function to get the type of a JSON value.
0 Comments
Read More
Leave a Reply. |