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GK One-Line Question & Answer

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DBMS → Introduction to DBMS 33

ANALYZE TABLE questions in MySQL
Analyzes and stores key distribution statistics for the optimizer
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MyISAM vs InnoDB: key difference
InnoDB supports transactions and FK; MyISAM does not (faster for read-heavy workloads)
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Row-level locking in InnoDB vs table-level locking in MyISAM
Row-level allows higher concurrency for writes; table-level blocks entire table
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Which MySQL data type stores IPv4 addresses efficiently
INT UNSIGNED (use INET_ATON/INET_NTOA for conversion)
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ENUM vs SET in MySQL: difference
ENUM: stores one value from list; SET: stores one or more values from list
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Which stores multiple selected values in one column
SET
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JSON column in MySQL 5.7+ allows
Binary JSON with validation and JSON path queries
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MySQL -> operator on JSON column
Extracts a JSON value: col->'$.key'
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MySQL ->> operator on JSON column
Extracts JSON value as unquoted string (JSON_UNQUOTE(JSON_EXTRACT(...)))
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Which MySQL function checks if JSON value contains a path
JSON_CONTAINS_PATH(json,'one','$.path')
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Generated/Computed column in MySQL is
A virtual or stored column whose value derived from an expression
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Which SQL creates a virtual generated column for full name
ALTER TABLE emp ADD full_name VARCHAR(100) AS (CONCAT(first_name,' ',last_name)) VIRTUAL
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Common Table Expression (CTE) scope
Only within the single query that defines it
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SQL:2003 MERGE statement equivalent in MySQL
INSERT ... ON DUPLICATE KEY UPDATE
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INSERT IGNORE in MySQL
Silently skips rows that would cause unique constraint violations
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REPLACE INTO in MySQL
Deletes existing row then inserts new one if PK/unique key conflicts
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Which SQL checks if a table exists before creating it
CREATE TABLE IF NOT EXISTS questions (...)
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Which MySQL function returns the last auto-increment ID inserted
LAST_INSERT_ID()
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PHP PDO lastInsertId() in Laravel context (DB::getPdo()->lastInsertId()) returns
The auto-increment ID of the last inserted row
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DB::table('questions')->insertGetId(['question'=>'Q?',...]) returns
The auto-increment ID of the newly inserted row
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DB::select vs DB::statement in Laravel
DB::select returns results; DB::statement returns boolean (for DDL/DML without results)
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Which prevents N+1 queries when loading questions with their assignment in Laravel
Question::with('assignment')->get()
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Question::has('reviews')->get() returns
Questions with reviews (at least one related review exists)
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Question::doesntHave('reviews')->get() returns
Questions with exactly 0 reviews (NO related review records exist)
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In Laravel migration, how to add index AFTER table creation
Schema::table('questions', function(Blueprint $t){ $t->index('q_level'); })
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Which Eloquent relationship loads in a separate query by default
Defined relationship accessed as property ($question->assignment)
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$question->load('assignment') in Eloquent performs
Lazy eager loading: loads relation on already-retrieved model without re-querying the model
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Question::latest()->get() orders by
created_at descending (most recent first)
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Question::oldest()->get() orders by
created_at ascending (oldest first)
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DB::table('questions')->when($level, function($q) use ($level){ $q->where('q_level',$level); })->get() performs
Conditionally applies where clause only if $level is truthy
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In Laravel, which method returns paginated results for API (without HTML links)
simplePaginate(15)
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Which Laravel relationship method uses a pivot table
belongsToMany()
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Pivot table for Question-Tag M:N relationship should be named
question_tag (singular model names in alphabetical order)
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DBMS → Transactions 4

Which MySQL engine supports ACID transactions
InnoDB
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Which Laravel method handles database transactions
DB::transaction(callback)
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DB::beginTransaction() followed by DB::commit() vs DB::rollBack()
beginTransaction starts explicit transaction; commit saves; rollBack undoes all changes
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Which Laravel method retries a transaction on deadlock
DB::transaction(callback,3) - second param is number of retry attempts
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DBMS → Joins 1

Lateral join (LATERAL keyword) allows
Subquery in FROM to reference columns from preceding FROM items in same query
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DBMS → DDL Commands 1

DROP TABLE IF EXISTS questions
Drops table only if it exists (no error if it doesn't exist)
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DBMS → SQL Basics 1

In Laravel, how to run raw SQL query
DB::select('SELECT * FROM questions WHERE id=?',[1])
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