SQL and PL/SQL Fundamentals

The trigger event (INSERT, UPDATE, or DELETE) determines execution frequency. Statement-level triggers fire once per statement, row-level fire once per affected row. Timing and type don't affect frequency.

PL/SQL requires exception handlers in order: WHEN OTHERS must be last. Here, WHEN no_data_found appears after WHEN OTHERS, causing compilation error. Also, Null is not a valid executable statement.

PL/SQL procedures accept positional (order-based), named (=> notation), or mixed notation. Options include just positional (B wrong) or just positional and named (A incomplete).

%ISOPEN is the cursor attribute that returns TRUE if a cursor is open. %OPEN doesn't exist. The syntax is cursor_name%ISOPEN.

In PL/SQL, %ROWTYPE provides a record type that represents a row in a database table. The record fields have the same names and data types as the columns of the table, allowing you to associate a variable with an entire row.

In Oracle, a sequence's CURRVAL pseudocolumn cannot be used until NEXTVAL has been called at least once in the current session. Since the sequence was just created and NEXTVAL has not been called, attempting to select CURRVAL will raise an error: ORA-08002: sequence ABC.CURRVAL is not yet defined in this session.

Oracle databases have a limit of 1000 columns per table or view. This is a hard limit in the Oracle database architecture. Option A (900) is too low, while options C (1100) and D (1050) exceed the actual limit.

The correct SQL cursor attributes in PL/SQL are: SQL%ROWCOUNT (number of rows affected), SQL%FOUND (boolean, true if at least one row affected), SQL%NOTFOUND (boolean, true if no rows affected), and SQL%ISOPEN (boolean, always false for implicit cursors). Option B incorrectly uses SQL%OPEN, and Option A incorrectly uses SQL%ISFOUND.

Raw types in databases store binary data directly without character encoding interpretation. This is distinct from character or ASCII data, which have specific encoding schemes. Raw types are used for images, files, or other non-text binary data.

Standard SQL itself does not have built-in structured exception handling (try/catch blocks). That functionality exists only in procedural SQL extensions like PL/SQL (Oracle) or T-SQL (SQL Server), not in core SQL.

BLOB (Binary Large Object) is the SQL data type designed to store unstructured binary data such as images, audio, video, or files. CLOB stores character data, LONG is for long text/numbers, and BLOB specifically handles binary up to large sizes (4GB in many systems).

In a PL/SQL block, only the DECLARE and EXCEPTION sections are optional. Every PL/SQL block must have BEGIN and END keywords to define the executable section. The DECLARE section (for declarations) and EXCEPTION section (for error handlers) can be omitted if not needed.

Database triggers are designed for centralized operations and ensuring related actions occur. They should not duplicate built-in constraints or other triggers. Option C describes enforcing related actions (e.g., audit logging on update). Option D describes global operations firing regardless of user.

In SQL mathematical expressions, you can use arithmetic operators like +, -, *, /, and parentheses () for grouping. The square bracket ] is not a valid SQL operator for math formulas. SQL uses standard mathematical notation.

In SQL, a column alias is assigned simply by placing the alias name after the column name, optionally with the AS keyword. The syntax 'SELECT column_name alias_name' is correct. Option A shows incorrect ALIAS keyword, and Option C just selects the alias as a column name.

Option C is valid: ROLLBACK with no active transaction is a no-op (does nothing harmlessly), then insert records, then COMMIT saves them. Option A is invalid because COMMIT then ROLLBACK makes no sense - records are already committed. Option D has redundant COMMIT. Option B has improper ROLLBACK sequence.

SQL uses underscore (_) as the single-character wildcard and percent (%) as the multiple-character wildcard in LIKE patterns. This is standard SQL syntax. The other options use file system wildcards (?, *) which are not used in SQL.

ROUND(8.9, 0) returns 9 (rounds up from 8.9) and TRUNC(8.9, 0) returns 8 (truncates decimal). So 9 > 8 is true. Option A: ROUND(4.5)=5, TRUNC(4.5)=4, so 5<4 is false. Option B compares 4 with 4, so 4<4 is false. Option D: ROUND(8.9,1)=8.9, TRUNC(8.95,2)=8.95, so 8.9>8.95 is false.

Triggers are indeed special stored procedures that automatically execute in response to certain events on a particular table or view - typically INSERT, UPDATE (modify), or DELETE operations. They're used to enforce business rules, maintain data integrity, or automate tasks without direct user intervention.

Stored procedures are precompiled collections of SQL statements and optional control-of-flow statements that are stored on the server. They provide a way to encapsulate business logic and database operations that execute server-side, reducing network traffic and improving security.