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6 min readIn Hibernate, mapping an entity to more than one entity type can be achieved through inheritance mapping strategies. Hibernate supports four inheritance mapping strategies: table per hierarchy, table per concrete class, table per subclass, and table per class.To properly map an entity to more than one entity type, you need to define a base entity class and then create subclasses for each entity type you want to map to.
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4 min readIf you want to pretty format JSON in Oracle, you can use the JSON_OBJECT function, which allows you to create JSON objects in a structured way. You can also use the JSON_QUERY function to extract values from a JSON document and format them in a readable way. Additionally, you can use the JSON_ARRAYAGG function to aggregate values from multiple rows into a single JSON array. These functions can help you format JSON data in a more organized and visually appealing manner.
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7 min readIn Hibernate, if you need to regenerate deleted sequence numbers, you can do so by adjusting the hibernate_sequence table in the database. Start by locating the hibernate_sequence table and find the respective row for the deleted sequence number. You can manually update the value in the next_val column to the desired sequence number that you want to regenerate.
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5 min readTo create an alias from a select result in Oracle, you can use the AS keyword followed by the desired alias name. For example, in a select statement like SELECT column_name AS alias_name FROM table_name;, "column_name" is the original name of the column and "alias_name" is the alias name you want to give to that column in the result set. Aliases can be helpful for making your query results more readable and for giving descriptive and easily identifiable names to your data.
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8 min readTo map a foreign key with Hibernate, you can use the @ManyToOne or @OneToOne annotation in your entity class. These annotations indicate that the entity has a many-to-one or one-to-one relationship with another entity. You can specify the target entity and the foreign key column using attributes of these annotations. Additionally, you can use the mappedBy attribute to specify the mapping on the other side of the relationship.
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3 min readTo create a function in Oracle, you first need to use the CREATE FUNCTION statement followed by the function name and parameters. Inside the function, you can write the logic for what the function should do, such as calculations or data manipulation. Make sure to specify the data type that the function will return. Once the function is defined, you can call it in SQL statements like any other function. Make sure to use proper error handling and testing to ensure the function works as expected.
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6 min readTo map results of a Hibernate query to a DTO object, you can create a constructor in the DTO class that can accept the result object as arguments in the same order as they are returned by the query. Then, in your Hibernate query, you can use the new keyword followed by the fully-qualified name of the DTO class with the arguments to instantiate the DTO object with the query results. Alternatively, you can also use a projection in the query to directly map the query results to the DTO object.
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6 min readRow_number() is a powerful function in Oracle SQL that assigns a unique sequential integer to each row within a partition of a result set. This function is commonly used in analytic queries to rank or order data based on specific criteria.To use row_number() in Oracle SQL, you need to include it as part of a SELECT statement with an OVER clause to define the partitioning and ordering of the rows. The basic syntax for using row_number() is as follows:SELECT column1, column2, ...
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![How to Map A Postgresql Text[] With Hibernate? preview](https://cdn.blogweb.me/1/66ad8432e67b5bed7820e3cd_242bc8bf0a.png)
6 min readTo map a PostgreSQL text[] array with Hibernate, you can use the @ElementCollection annotation in your entity class along with specifying the @CollectionTable and @Column annotations to map the array to the corresponding database table and column. Make sure to also specify the type of the array elements using the @Type annotation. Additionally, you may need to implement a custom user type to handle the conversion between the PostgreSQL array and Java array in Hibernate.
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3 min readIn Oracle, the equivalent for @@error in SQL Server is the SQLCODE function. SQLCODE returns the numeric error code for the last executed SQL statement. It is often used in conjunction with the SQLERRM function, which returns the error message associated with the error code. Together, SQLCODE and SQLERRM can be used to handle and display errors in Oracle PL/SQL code.[rating:dc3bb8f1-bf14-46f8-a39b-16fc925c6a8c]How to rollback transactions in case of errors in Oracle.
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5 min readConcurrency in Hibernate can be implemented by utilizing optimistic locking mechanisms. This is achieved by adding a version attribute to the entity class which is annotated with @Version. When an entity is updated, Hibernate checks if the version attribute in the database matches the one in the entity being updated. If they do not match, a StaleObjectStateException is thrown which indicates that another user has already made changes to the entity.