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Computer Fundamentals → Introduction to Computer 39

DESCRIBE table_name in MySQL?
Shows table structure (column names, types, constraints)
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EXPLAIN in SQL is used for?
Showing query execution plan for performance analysis
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Which MySQL statement modifies table structure?
ALTER TABLE
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Which constraint ensures unique values in a column?
UNIQUE
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CHECK constraint in SQL?
Validates that column values meet specified condition
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DEFAULT constraint in SQL?
Specifies a default value when no value is provided during INSERT
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Stored procedure advantages include?
Pre-compiled execution, reduced network traffic, code reuse, security
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Function vs Stored Procedure in SQL?
Functions must return a value and can be used in SELECT; procedures can't be in SELECT
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Trigger AFTER INSERT fires?
After a row is successfully inserted into the table
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BEFORE DELETE trigger is used to?
Perform actions before a row is deleted (e.g., archive data)
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Which SQL view cannot be updated?
View with GROUP BY, DISTINCT, aggregates, or multiple tables (in most cases)
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Database cursor is used for?
Row-by-row processing of query results
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COMMIT in SQL?
Permanently saves all changes made in the current transaction
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ROLLBACK in SQL?
Undoes all changes made since the last COMMIT or SAVEPOINT
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SAVEPOINT in SQL allows?
Partial rollback to a named point within a transaction
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Which isolation level prevents dirty reads, phantom reads, and non-repeatable reads?
Serializable
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Dirty read in databases occurs when?
Transaction reads uncommitted data from another transaction
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Phantom read occurs when?
Same query returns different rows in same transaction due to another transaction's INSERT/DELETE
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Database sharding is?
Horizontal partitioning of data across multiple database instances
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Read replica in databases is used for?
Scaling read operations — copy of primary database for SELECT queries
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Connection pooling in applications?
Reuses existing database connections from a pool — improves performance
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ORM (Object Relational Mapping) maps?
Object-oriented code classes to database tables automatically
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Which NoSQL type stores data as key-value pairs?
Key-value store
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Which data type in Python is immutable?
Tuple
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Python list comprehension [x*2 for x in range(5)] produces?
[0,2,4,6,8]
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What does len([1,2,3,4,5]) return in Python?
5
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Python dictionary key must be?
Immutable (string, int, tuple)
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Which Python keyword is used to handle exceptions?
except
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What is the output of print(type(3.14)) in Python?
<class 'float'>
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Python's 'pass' statement?
Does nothing — placeholder for empty code block
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Which Python function converts integer to string?
str()
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Python range(1,10,2) generates?
[1,3,5,7,9]
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Lambda in Python is?
An anonymous function defined in one line
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What does *args in Python function mean?
Variable number of positional arguments as tuple
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**kwargs in Python?
Variable number of keyword arguments as dictionary
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Python decorator is used to?
Wrap a function to modify or extend its behavior without changing its code
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Generator in Python uses which keyword?
yield
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Python 'with' statement is used for?
Context management — automatically handles resource cleanup (close files)
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What does __init__ method do in Python class?
Constructor — initializes a new object instance's attributes
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Computer Fundamentals → Memory Units 1

Materialized view differs from regular view because?
Stores the query result physically — must be refreshed to stay current
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