Database and SQL

The correct method name is SaveChanges(), which persists all pending changes to the database. This is the standard method on DbContext in Entity Framework. Options A and D are non-existent method names, while B (Save()) is incomplete - the actual method is SaveChanges().

Entity SQL is specifically designed for building and executing dynamic queries at runtime, as it's a string-based query language similar to traditional SQL. LINQ to Entities is compile-time bound and not suitable for truly dynamic queries. LINQ to SQL is a different technology for SQL Server specifically, not Entity Framework.

AcceptChanges is the specific method in DataSet/DataTable that commits all pending changes since the last AcceptChanges call. It updates the RowState of all rows to Unchanged. Update is a DataAdapter method for database synchronization, GetChanges returns pending changes, and Accept is not a valid method.

NewRow() creates a new DataRow object with the schema of the table but does NOT add it to the table's Rows collection - you must call DataTable.Rows.Add() afterward. Add() directly adds to the collection. Read() and ExecuteReader() are data retrieval methods.

Hibernate does not allow mixing table-per-class hierarchy (union subclass) and table-per-subclass (joined subclass) inheritance strategies within the same inheritance hierarchy. You must choose one strategy per inheritance hierarchy. Mixing these strategies would create ambiguous mappings and is not supported by Hibernate.

Setting insert="false" and update="false" in Hibernate mapping prevents the property from being included in INSERT and UPDATE statements. The property can still be read from the database but won't be modified during save operations. This is useful for database columns that are managed by triggers or are derived/calculated values.

In Hibernate, Session.get() immediately queries the database and returns null if the corresponding row does not exist, which is ideal when existence is uncertain. Conversely, Session.load() assumes the row exists, returns a proxy, and throws an exception later if the record is missing.

The INTO clause must appear AFTER the SELECT clause in PL/SQL cursor declarations. The correct order is: CURSOR name IS SELECT columns INTO variables FROM table WHERE condition. Here 'into my_city, my_state' appears before 'from CITIES', which is a syntax error.

In Hibernate, a Bag collection permits duplicate element values and does not maintain index information. Unlike List which requires an index column, Bag is like an unordered collection that allows duplicates. This makes it simpler but less powerful than List for ordering operations.

To delete all rows from a table T1, use 'DELETE FROM T1'. Option A is incorrect because DELETE doesn't use '*'. Option B is incorrect because 'all' is not valid SQL syntax. Option C is incorrect for the same reason as A. The correct syntax is DELETE FROM table_name with no WHERE clause.

In DB2, an Alias is an alternative name for a View. Aliases cannot be created for Sequences, Triggers, or Schemas. An Alias provides a way to reference a View with a different name, which can be useful for simplifying names or providing application-specific naming.

Triggers are fired by DML operations (INSERT, UPDATE, DELETE). Among the options, only Delete is a DML operation that can cause a trigger to fire. Drop and Alter are DDL operations and don't fire triggers. Rollback is a transaction control command, not a DML operation.

A view is a virtual table that stores only a query definition, not data. Every time an executable SQL statement references the view, the underlying query executes to produce the result set dynamically - the view is repopulated on each reference.

INSTEAD OF triggers can be created on views to intercept insert, update, or delete operations against the view and redirect them to the underlying base tables. Triggers cannot be created on catalog tables, stored procedures, or global temporary tables.