MCQs

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Overall MCQs for Reference

Which clause is used to fetch data from two or more tables, based on conditions between tables?
a. Combine
b. Join
c. Merge
d. Add
Answer: b. Joinsanfoundry
What is the main purpose of the SQL JOIN clause?
a. To delete records
b. To fetch data from multiple tables
c. To update tables
d. To change table schema
Answer: b. To fetch data from multiple tablesinterviewbit
Which SQL JOIN type returns only rows that have matching values in both tables?
a. Outer join
b. Left join
c. Right join
d. Inner join
Answer: d. Inner jointestbook+1
How many main types of JOIN are most commonly used in SQL?
a. Two
b. Three
c. Four
d. Five
Answer: c. Foursanfoundry+2
The clause that must contain a join condition for joining two tables is:
a. GROUP BY
b. HAVING
c. FROM or WHERE
d. ORDER BY
Answer: c. FROM or WHEREincludehelp
Which SQL JOIN returns all records from the left table and matching records from the right table?
a. Right join
b. Full join
c. Left join
d. Self join
Answer: c. Left joinw3schools+2
Which SQL JOIN returns all records from the right table and matching records from the left table?
a. Left join
b. Full join
c. Right join
d. Inner join
Answer: c. Right jointestbook+1
What does a FULL JOIN return?
a. Only matching rows
b. All rows from both tables, with NULLs for non-matching rows
c. Only rows from left table
d. Only unmatched rows
Answer: b. All rows from both tables, with NULLs for non-matching rowsigmguru+2
Which SQL JOIN type creates a Cartesian product of two tables?
a. Self join
b. Cross join
c. Full join
d. Left join
Answer: b. Cross joinscholarhat+1
What is required for performing a JOIN?
a. Rows must be equal
b. A related column between tables
c. Same data types in all columns
d. Primary key only
Answer: b. A related column between tablesknowledgehut+1
In an INNER JOIN, which table’s missing rows are excluded from the output?
a. Left table only
b. Right table only
c. Both tables
d. Neither table
Answer: c. Both tablesgeeksforgeeks+2
Which JOIN includes all rows from both tables, replacing unmatched columns with NULLs?
a. LEFT JOIN
b. RIGHT JOIN
c. FULL JOIN
d. INNER JOIN
Answer: c. FULL JOINdatalemur+1
To combine records from two tables where a matching value exists, which JOIN is used?
a. INNER JOIN
b. OUTER JOIN
c. RIGHT JOIN
d. CROSS JOIN
Answer: a. INNER JOINsanfoundry+1
What is the default JOIN type in SQL when only JOIN is written?
a. Outer join
b. Inner join
c. Left join
d. Right join
Answer: b. Inner joinsanfoundry
Which JOIN is frequently used to identify unmatched data?
a. LEFT JOIN
b. INNER JOIN
c. SELF JOIN
d. CROSS JOIN
Answer: a. LEFT JOINscholarhat
Which JOIN allows combining data horizontally into new columns?
a. UNION
b. JOIN
c. SELECT
d. INSERT
Answer: b. JOINdatacamp+1
What does a SELF JOIN do?
a. Joins two tables of different types
b. Joins a table with itself
c. Joins based on a foreign key
d. Joins unrelated tables
Answer: b. Joins a table with itselfdatalemur+1
Which JOIN type returns all possible combinations of row pairs from two tables?
a. INNER JOIN
b. CROSS JOIN
c. LEFT JOIN
d. FULL JOIN
Answer: b. CROSS JOINsanfoundry+1
What is a join condition?
a. The reason you join tables
b. A condition that determines how rows from two tables are combined
c. The number of columns to be joined
d. The type of tables used
Answer: b. A condition that determines how rows from two tables are combinedknowledgeboat+1
Which JOIN is used if you want all the rows from the right table with matching rows from the left table?
a. LEFT JOIN
b. FULL JOIN
c. RIGHT JOIN
d. CROSS JOIN
Answer: c. RIGHT JOINw3schools+1
Which JOIN would you use to identify all employees regardless of whether they have sales orders?
a. INNER JOIN between Employees and SalesOrders
b. LEFT JOIN between Employees and SalesOrders
c. RIGHT JOIN between Employees and SalesOrders
d. CROSS JOIN
Answer: b. LEFT JOIN between Employees and SalesOrdersgeeksforgeeks+1
If a JOIN produces more rows than any individual table, it’s likely a:
a. INNER JOIN
b. CROSS JOIN
c. RIGHT JOIN
d. SELF JOIN
Answer: b. CROSS JOINscholarhat+1
Which SQL keyword is necessary for specifying join conditions?
a. ON
b. IN
c. AS
d. BY
Answer: a. ONknowledgehut
Which JOIN does not require a related column and produces all possible row combinations?
a. LEFT JOIN
b. RIGHT JOIN
c. CROSS JOIN
d. INNER JOIN
Answer: c. CROSS JOINw3schools+1
Which type of JOIN is best for displaying all records, matched or not, from both tables?
a. LEFT JOIN
b. FULL JOIN
c. RIGHT JOIN
d. INNER JOIN
Answer: b. FULL JOINdatalemur
What’s true about EQUIJOIN in SQL?
a. It’s the same as INNER JOIN where condition is equality
b. It returns unmatched rows
c. No condition required
d. Used for outer joins
Answer: a. It’s the same as INNER JOIN where condition is equalitysanfoundry+1
Which JOIN type is useful when querying hierarchical or recursive relations?
a. CROSS JOIN
b. LEFT JOIN
c. SELF JOIN
d. FULL JOIN
Answer: c. SELF JOINgeeksforgeeks+1
What JOIN type includes all records from Table A even if there is no match in Table B?
a. LEFT JOIN
b. FULL JOIN
c. RIGHT JOIN
d. INNER JOIN
Answer: a. LEFT JOINw3schools+1
What is true about INNER JOIN and NULL values?
a. NULLs are included
b. Only matched values are included; unmatched rows with NULLs are omitted
c. NULLs are converted to zero
d. It only works for numeric data
Answer: b. Only matched values are included; unmatched rows with NULLs are omitteddatalemur+1
Which clause controls the rows to be output after the tables have been joined?
a. WHERE clause
b. HAVING clause
c. SELECT clause
d. GROUP BY clause
Answer: a. WHERE clausemode+1
Which type of JOIN is used for many-to-many relationships in data science tables?
a. INNER JOIN
b. CROSS JOIN
c. UNION
d. LEFT JOIN
Answer: a. INNER JOINinterviewbit+1
What happens if no join condition is specified in a JOIN clause?
a. Syntax error
b. Returns Cartesian product
c. Returns no rows
d. Returns all rows from first table only
Answer: b. Returns Cartesian productsanfoundry+1
When combining student info with course enrollments, which JOIN is most common?
a. LEFT JOIN
b. INNER JOIN
c. RIGHT JOIN
d. FULL JOIN
Answer: b. INNER JOINknowledgehut+1
The result of matching columns in two tables using equal sign in JOIN is a(n):
a. EQUIJOIN
b. OUTER JOIN
c. UNION JOIN
d. NATURAL JOIN
Answer: a. EQUIJOINknowledgehut+1
Which JOIN is used to return all rows from both tables, with unmatched rows in both tables having NULLs?
a. LEFT JOIN
b. FULL OUTER JOIN
c. INNER JOIN
d. CROSS JOIN
Answer: b. FULL OUTER JOINw3schools+1
What must both tables have to be joined using INNER JOIN?
a. Same number of rows
b. Common column
c. Same data types in all columns
d. Primary key
Answer: b. Common columninterviewbit+1
Which clause is used to join tables on a specific condition?
a. ON clause
b. BY clause
c. TO clause
d. AS clause
Answer: a. ON clausemode+1
Which JOIN combines every row of Table A with every row of Table B?
a. INNER JOIN
b. CROSS JOIN
c. LEFT JOIN
d. RIGHT JOIN
Answer: b. CROSS JOINscholarhat+1
For returning all data from the left table and the matched data from the right, use:
a. INNER JOIN
b. LEFT JOIN
c. RIGHT JOIN
d. FULL JOIN
Answer: b. LEFT JOINtestbook+1
Which type of JOIN may create NULLs in both tables’ output?
a. FULL OUTER JOIN
b. INNER JOIN
c. RIGHT JOIN
d. SELF JOIN
Answer: a. FULL OUTER JOINtestbook+1
Which JOIN helps find records present in one table but not in another?
a. LEFT JOIN with WHERE
b. INNER JOIN
c. FULL JOIN
d. CROSS JOIN
Answer: a. LEFT JOIN with WHEREdatalemur
A join operation to merge two sorted datasets is called:
a. Merge join
b. Union join
c. Cross join
d. Sort join
Answer: a. Merge joininterviewbit
What’s different about UNION clause compared to JOIN clause?
a. UNION is used for row-wise concatenation, JOIN for column-wise
b. UNION uses ON clause
c. UNION is only for numeric columns
d. UNION cannot combine tables
Answer: a. UNION is used for row-wise concatenation, JOIN for column-wisedatacamp+1
What type of JOIN includes all records from the right table even if there are no matches in the left?
a. RIGHT JOIN
b. LEFT JOIN
c. INNER JOIN
d. FULL JOIN
Answer: a. RIGHT JOINtestbook+1
Which join lets you combine a table with itself for comparison?
a. FULL JOIN
b. SELF JOIN
c. INNER JOIN
d. CROSS JOIN
Answer: b. SELF JOINscholarhat+1
Which JOIN is used most often for one-to-many relationships (e.g., Customers and Orders)?
a. INNER JOIN
b. FULL JOIN
c. LEFT JOIN
d. UNION
Answer: a. INNER JOINinterviewbit+1
What SQL clause specifies additional filters after JOINs?
a. WHERE
b. HAVING
c. GROUP BY
d. ORDER BY
Answer: a. WHEREmode+1
Which JOIN is ideal for getting every possible combination of the two datasets?
a. RIGHT JOIN
b. CROSS JOIN
c. LEFT JOIN
d. INNER JOIN
Answer: b. CROSS JOINscholarhat+1
What is achieved by using LEFT JOIN followed by checking for NULL in the right table?
a. Finding unmatched rows from left table
b. Finding only matched rows
c. Updating right table
d. None of the above
Answer: a. Finding unmatched rows from left tablegeeksforgeeks+1
Which JOIN returns only those rows where there is a match in all joined tables?
a. FULL JOIN
b. CROSS JOIN
c. INNER JOIN
d. LEFT JOIN
Answer: c. INNER JOINsanfoundry+1

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