Posts (page 117)
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8 min readWhen choosing the right cascade type for a Hibernate entity, it is important to consider the relationships and behaviors between the entities involved.Cascade types determine how changes to one entity should propagate to related entities.
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4 min readTo ignore null values at the end of a string in Oracle, you can use the TRIM function along with the TRAILING keyword. The TRIM function removes specified characters from the beginning or end of a string, while the TRAILING keyword specifically targets characters at the end of the string. By combining TRIM with TRAILING and specifying the null character as the character to remove, you can effectively ignore any null values at the end of a string in Oracle.
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5 min readLazy collections in Hibernate are collections of objects that are only loaded from the database when they are accessed for the first time. This is done to improve performance and prevent unnecessary loading of data that may not be needed.To load lazy collections in Hibernate, you can use various methods such as using the Hibernate.initialize() method, accessing the collection within a transaction, or using fetch join in HQL queries.
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4 min readIn Oracle, triggers are named database objects that are automatically executed or fired when certain events occur in a table or view. These events can be INSERT, UPDATE, DELETE, or TRUNCATE operations on the table. Triggers can be used to enforce business rules, perform custom actions, or maintain data integrity.
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7 min readIn Hibernate, you can get the changed properties before updating an object by using the Session interface and the DirtyChecker interface.First, you need to obtain the Session object by calling sessionFactory.getCurrentSession(). Then, retrieve the DirtyChecker instance by calling session.getSessionFactory().getMetamodel().entityPersister(entityClass).getEntityTuplizer().getEntityMetamodel().getBytecodeEnhancementMetadata().getDirtyTracker().
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3 min readTo select two columns with one as the maximum value in Oracle, you can use a subquery to find the maximum value in one column and then join it with the original table based on that maximum value using a WHERE clause. This way, you can retrieve the corresponding values from the other column in the same row as the maximum value in the first column.[rating:dc3bb8f1-bf14-46f8-a39b-16fc925c6a8c]How to handle multiple max values in Oracle.
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6 min readTo optimize the hibernate execution time, you can follow several strategies. First, make sure to properly configure and tune your database connection pool to efficiently manage connections to the database. This can help reduce the time spent on establishing and closing connections.Additionally, configure hibernate caching to store frequently accessed data in memory, reducing the need for frequent database queries. Use second-level caching for entity and query caching to improve performance.
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5 min readTo trim the text in different columns in Oracle, you can use the TRIM function. This function allows you to remove specified characters from the beginning or end of a string. You can specify the characters you want to remove as the second argument in the TRIM function.
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7 min readIn Hibernate, a composite foreign key mapping refers to mapping a composite primary key from one table to a composite foreign key in another table. To define a composite foreign key mapping in Hibernate, you need to use the @ManyToOne annotation along with @JoinColumns annotation on the entity class that represents the many side of the relationship. The @JoinColumns annotation allows you to specify multiple columns that make up the composite foreign key.
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7 min readTo select the value from an XML field in an Oracle query, you can use the XMLType function to convert the XML data into a format that allows for querying. Once the XML data is converted, you can then use XPath expressions to navigate through the XML structure and retrieve the desired values. By using the XMLTable function, you can extract specific values from the XML field and include them in your query results.
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5 min readTo get the size of the Hibernate connection pool, you can look into the configuration settings of your Hibernate framework. The size of the connection pool is typically defined in the Hibernate configuration file, which is usually named hibernate.cfg.xml or hibernate.properties.In the configuration file, you will find a property that specifies the maximum number of connections that can be created in the pool. This property is often named "hibernate.c3p0.
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7 min readTo safely reset an Oracle sequence, you can follow these steps:Query the current value of the sequence using the following SQL statement: SELECT your_sequence.NEXTVAL FROM DUAL; Note down the current value returned by the query.