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SQL Quiz (200 Questions)

199 exercises10 free
  1. 01What Does SQL Stand For?
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  2. 02Which Part Of SQL Is Primarily Used To Retrieve Data?
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  3. 03SQL Is Programming Language For Storing And Processing Information In?
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  4. 04Which Keyword Begins A Query That Retrieves Data From A Table?
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  5. 05SQL Is Considered What Type Of Language?
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  6. 06Which Of The Following Is A Common Relational Database System?
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  7. 07Which Keyword Removes Duplicates In A SELECT Statement?
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  8. 08Which Statement Changes Data In A Database?
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  9. 09n SQL, Which Symbol Is Commonly Used As A Wildcard In Strings?
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  10. 10Which Command Is Used To Remove Rows From A Table?
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  11. 11Which Clause Specifies The Source Table(S) In A Query?
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  12. 12Which Keyword Selects All Columns From A Table?
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  13. 13To Select A Literal String “Hello”, You Can Write:
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  14. 14To Rename A Column In The Result Set, Use:
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  15. 15If You Omit FROM, Selecting From Where Is Possible In Standard SQL?
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  16. 16To Choose Columns “Name” And “Age” From Table “Persons”:
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  17. 17A SELECT Statement Without A WHERE Clause Returns:
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  18. 18To Avoid Specifying A Table Alias, You Can:
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  19. 19Which Of These Is A Valid SELECT Syntax?
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  20. 20Using SELECT Without Specifying Columns Returns:
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  21. 21The WHERE Clause Is Used To:
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  22. 22To Select Rows Where Age > 18:
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  23. 23To Match Rows Where Name Starts With ‘A’:
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  24. 24To Select Rows Where City Is Either ‘Paris’ Or ‘London’:
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  25. 25The WHERE Clause Is Placed:
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  26. 26To Find Rows Where Salary Is NOT 5000:
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  27. 27Which Operator Checks For NULL Values?
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  28. 28To Exclude Rows With Age = 30:
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  29. 29To Use A Pattern To Filter Rows Containing ‘Abc’ Anywhere In Name:
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  30. 30To Filter Rows Where Price Is Between 10 And 20 Inclusive:
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  31. 31Which Function Returns The Number Of Rows?
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  32. 32SUM() Function Is Used To:
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  33. 33MIN() Function Returns:
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  34. 34MAX() Function Returns:
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  35. 35AVG() Function Returns:
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  36. 36COUNT(*) Differs From COUNT(Column) By:
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  37. 37To Get Total Sales From ‘Orders’ Table With ‘Amount’ Column:
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  38. 38To Find The Lowest Salary In Employees Table:
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  39. 39To Count Rows Ignoring NULL In Column ‘Age’:
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  40. 40Which Function Can Remove Duplicates When Counting Distinct Values?
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  41. 41GROUP BY Is Used To:
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  42. 42GROUP BY Must Be Used With:
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  43. 43HAVING Clause Filters Rows After:
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  44. 44To Find Total Sales Per Department:
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  45. 45HAVING Is Used To Filter Groups, For Example Groups With SUM(Sales)>1000:
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  46. 46If A SELECT Uses GROUP BY, Columns Not Aggregated Must Be:
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  47. 47Average Salary By Job_title But Only Show Groups With Avg>5000:
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  48. 48Without GROUP BY, HAVING Acts Like WHERE, But Standard SQL Requires:
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  49. 49Count Employees Per Department And Only Show Departments With Count>10:
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  50. 50You Cannot Use HAVING Without What?
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  51. 51ORDER BY Is Used To:
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  52. 52By Default ORDER BY Sorts In:
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  53. 53To Sort By Name Ascending And Age Descending:
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  54. 54ORDER BY Must Come:
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  55. 55To Sort By A Column Not In SELECT, Generally:
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  56. 56To Sort By Multiple Columns, Separate By:
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  57. 57To Get Alphabetical Order On ‘Name’:
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  58. 58To Reverse The Sorting Order:
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  59. 59If No ORDER BY Specified, Order Of Rows Is:
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  60. 60ORDER BY Can Sort By Column Position Using:
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  61. 61INNER JOIN Returns:
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  62. 62LEFT JOIN Returns:
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  63. 63RIGHT JOIN Returns:
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  64. 64FULL OUTER JOIN Returns:
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  65. 65To Join ‘Orders’ And ‘Customers’ Where Orders.cust_id=Customers.id:
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  66. 66INNER JOIN Is Also Called:
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  67. 67To Get All Customers Even If They Have No Orders:
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  68. 68CROSS JOIN Returns:
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  69. 69To Filter Joined Results, Use Conditions In:
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  70. 70If You Want All Rows From Both Tables With No Match Replaced By NULLs:
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  71. 71A Subquery Is:
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  72. 72Subqueries Are Often Used In:
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  73. 73A Scalar Subquery Returns:
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  74. 74To Find Rows With Value Greater Than The Average, Use:
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  75. 75A Derived Table Is A Subquery Used:
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  76. 76A Subquery Returning Multiple Values Can Be Used With:
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  77. 77Correlated Subqueries:
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  78. 78To Use A Subquery As A Column List:
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  79. 79Subqueries Can Appear In:
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  80. 80A Derived Table Must Have:
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  81. 81UNION Combines:
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  82. 82UNION Requires:
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  83. 83UNION By Default Removes Duplicates. To Keep Duplicates Use:
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  84. 84INTERSECT Returns:
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  85. 85EXCEPT Returns:
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  86. 86Set Operations Typically Require:
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  87. 87UNION ALL Vs UNION Differs By:
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  88. 88INTERSECT And EXCEPT Might Not Be Supported By All SQL Dialects. A Common Replacement For INTERSECT Is:
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  89. 89Set Operators Combine Results Of Multiple SELECTs. The Correct Syntax Usually Is:
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  90. 90EXCEPT Is Sometimes Known As:
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  91. 91CREATE TABLE Is Used To:
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  92. 92B. Removes table structure and data
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  93. 93ALTER TABLE Is Used To:
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  94. 94To Remove A Column From A Table:
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  95. 95CREATE TABLE Syntax Generally Includes:
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  96. 96To Rename A Table:
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  97. 97To Add A New Column:
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  98. 98DDL Statements Like CREATE, DROP, ALTER Usually:
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  99. 99To Completely Remove A Table And Its Data:
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  100. 100To Remove All Rows But Keep Table Structure:
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  101. 101INSERT Is Used To:
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  102. 102UPDATE Changes:
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  103. 103DELETE Removes:
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  104. 104INSERT INTO Table (Col1, Col2) VALUES (Val1, Val2):
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  105. 105To Update A Row’s Salary In Employees:
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  106. 106DELETE FROM Table WHERE Condition:
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  107. 107To Insert Multiple Rows At Once (Some Dialects Allow):
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  108. 108Without WHERE In UPDATE Or DELETE:
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  109. 109INSERT Can Be Combined With SELECT To:
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  110. 110TRUNCATE TABLE Differs From DELETE Because:
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  111. 111PRIMARY KEY Ensures:
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  112. 112FOREIGN KEY Enforces:
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  113. 113UNIQUE Constraint Ensures:
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  114. 114NOT NULL Ensures:
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  115. 115CHECK Constraint Allows:
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  116. 116A Table Can Have How Many PRIMARY KEY Constraints?:
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  117. 117FOREIGN KEY References:
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  118. 118UNIQUE Differs From PRIMARY KEY In That:
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  119. 119To Ensure Age > 0 In A Column, Use:
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  120. 120Constraints Are Defined Usually In:
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  121. 121A VIEW Is:
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  122. 122CREATE VIEW Syntax Includes:
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  123. 123A MATERIALIZED VIEW Is:
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  124. 124Views Can Be Used To:
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  125. 125To Refresh A Materialized View (In Systems That Support It):
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  126. 126Dropping A View:
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  127. 127Some Views Are Updatable If:
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  128. 128A View Does Not Physically Store Data Except:
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  129. 129To Ensure View Runs A Complex Query Efficiently Without Recalculating Each Time, Use:
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  130. 130Views Can Be Used For Security By:
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  131. 131An Index Is Used To:
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  132. 132A Primary Key Usually Creates:
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  133. 133Adding Too Many Indexes Can:
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  134. 134A Clustered Index:
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  135. 135Non-Clustered Index Stores:
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  136. 136To Analyze Query Performance, One Might Use:
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  137. 137Indexes Help SELECT Queries But Can Slow Down:
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  138. 138A Good Candidate For Indexing Is:
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  139. 139Removing Unused Indexes Can:
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  140. 140Indexes Are Created By:
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  141. 141A Window Function Is Defined Using:
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  142. 142Window Functions Allow Calculations:
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  143. 143PARTITION BY In Window Functions:
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  144. 144ROW_NUMBER() Function:
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  145. 145RANK() Vs ROW_NUMBER():
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  146. 146LAG() And LEAD() Functions Allow:
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  147. 147NTILE(N) Divides Rows Into:
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  148. 148To Use Window Functions, OVER Clause Is Mandatory Because:
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  149. 149Window Functions Do Not Collapse Rows Like GROUP BY. They:
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  150. 150ORDER BY Inside OVER(…) Defines:
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  151. 151A CTE Starts With:
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  152. 152A CTE Is Defined For:
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  153. 153CTEs Can Be Used To:
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  154. 154A CTE Resembles A Derived Table, But:
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  155. 155Recursive CTEs Allow:
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  156. 156Syntax Of A Basic CTE:
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  157. 158CTEs Are Not Stored Persistently; They Are:
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  158. 159Recursive CTEs Need:
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  159. 160CTEs Improve Readability Compared To:
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  160. 161String Functions Like LENGTH() Or CHAR_LENGTH() Return:
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  161. 162SUBSTRING(String, Start, Length) Extracts:
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  162. 163UPPER() And LOWER() Functions Change String Case To:
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  163. 164Date Functions Like NOW() Or CURRENT_DATE():
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  164. 165EXTRACT(YEAR FROM Date) Returns:
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  165. 166DATEADD Or ADD_MONTHS Are Used To:
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  166. 167CASE Expression Allows:
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  167. 168CASE WHEN Condition THEN Value ELSE Other END:
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  168. 169String Functions Like CONCAT(S1,S2):
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  169. 170COALESCE(Expr1, Expr2, …) Returns:
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  170. 171A Stored Procedure Is:
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  171. 172A Stored Function Differs From A Procedure By:
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  172. 173CREATE PROCEDURE Syntax Varies By Dialect, But Generally Includes:
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  173. 174Stored Procedures Can Improve Performance By:
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  174. 175Functions Are Often Used In SELECT Statements Because:
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  175. 176Stored Procedures Can Accept IN, OUT Parameters To:
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  176. 177In PL/SQL Or T-SQL, You Can Write:
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  177. 178To Drop A Stored Procedure:
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  178. 179Stored Functions Must:
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  179. 180Procedures And Functions Enhance:
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  180. 181A Transaction Is:
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  181. 182COMMIT Saves Changes Made During A Transaction:
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  182. 183ROLLBACK Undoes:
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  183. 184BEGIN Or START TRANSACTION Begins:
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  184. 185Isolation Levels Define:
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  185. 186A Common Isolation Level Is:
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  186. 187Locking Is Used To Prevent:
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  187. 188Deadlocks Occur When:
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  188. 189COMMIT Ends A Transaction And Makes Changes:
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  189. 190SAVEPOINT Allows:
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  190. 191Partitioning A Table Means:
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  191. 192Horizontal Partitioning Splits Data By:
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  192. 193Vertical Partitioning Splits Data By:
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  193. 194Sharding Is A Form Of Partitioning Where:
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  194. 195Caching Query Results In Memory Can:
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  195. 196vertical Partitioning Splits Data By:
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  196. 197Table Partitioning Can Improve Performance By:
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  197. 198Parallel Query Execution Means:
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  198. 199Compression In Databases Can:
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  199. 200Advanced Partitioning Strategies And Indexing Can Lead To:
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