1. Case Statements:
2.  
3. sql
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5. SELECT column1, column2,
6.   CASE
7.     WHEN condition1 THEN result1
8.     WHEN condition2 THEN result2
9.     ELSE result3
10.   END AS alias
11. FROM table_name;
12. Subqueries:
13.  
14. sql
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16. SELECT column1
17. FROM table1
18. WHERE column2 IN (SELECT column3 FROM table2 WHERE condition);
19. Keys:
20.  
21. Primary Key:
22.  
23. sql
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25. CREATE TABLE table_name (
26.   id INT PRIMARY KEY,
27.   column1 datatype,
28.   column2 datatype,
29.   ...
30. );
31. Foreign Key:
32.  
33. sql
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35. CREATE TABLE table_name (
36.   id INT PRIMARY KEY,
37.   foreign_id INT,
38.   column1 datatype,
39.   column2 datatype,
40.   FOREIGN KEY (foreign_id) REFERENCES other_table(id)
41. );
42. Wildcards:
43.  
44. sql
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46. SELECT column1
47. FROM table_name
48. WHERE column2 LIKE 'abc%'; Case Statements:
49.  
50. sql
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52. SELECT column1, column2,
53.   CASE
54.     WHEN condition1 THEN result1
55.     WHEN condition2 THEN result2
56.     ELSE result3
57.   END AS alias
58. FROM table_name;
59. Subqueries:
60.  
61. sql
62. Copy code
63. SELECT column1
64. FROM table1
65. WHERE column2 IN (SELECT column3 FROM table2 WHERE condition);
66. Keys:
67.  
68. Primary Key:
69.  
70. sql
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72. CREATE TABLE table_name (
73.   id INT PRIMARY KEY,
74.   column1 datatype,
75.   column2 datatype,
76.   ...
77. );
78. Foreign Key:
79.  
80. sql
81. Copy code
82. CREATE TABLE table_name (
83.   id INT PRIMARY KEY,
84.   foreign_id INT,
85.   column1 datatype,
86.   column2 datatype,
87.   FOREIGN KEY (foreign_id) REFERENCES other_table(id)
88. );
89. Wildcards:
90.  
91. sql
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93. SELECT column1
94. FROM table_name
95. WHERE column2 LIKE 'abc%'
96.  
97.  
98. Certainly! Here's an example of performing the ORDER BY clause on two columns in the EMPLOYEE table:
99.  
100. sql
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102. SELECT empId, name, dept, grade
103. FROM EMPLOYEE
104. ORDER BY grade DESC, name ASC;
105. In this example, the ORDER BY clause is applied to the grade column in descending order (DESC) first. Then, if there are multiple rows with the same grade, the name column is used to sort those rows in ascending order (ASC).
106.  
107. The result will be a sorted result set where the rows are arranged based on the grade in descending order. Within each grade, the rows will be further sorted based on the name in ascending order.
108.  
109. You can modify the column names and the sort order based on your specific requirements. Simply specify the desired columns in the ORDER BY clause and indicate whether you want them sorted in ascending (ASC) or descending (DESC) order.
110.  
111. select avg(grade) from EMPLOYEE
112. select avg(grade) from EMPLOYEE where dept='Accounting'
113. select * from EMPLOYEE where grade<(select avg(grade) from EMPLOYEE where dept='Accounting')
114.  
115.  
116.  
117. Certainly! Here's an example of performing the ORDER BY clause on two columns in the EMPLOYEE table:
118.  
119. sql
120. Copy code
121. SELECT empId, name, dept, grade
122. FROM EMPLOYEE
123. ORDER BY grade DESC, name ASC;
124. In this example, the ORDER BY clause is applied to the grade column in descending order (DESC) first. Then, if there are multiple rows with the same grade, the name column is used to sort those rows in ascending order (ASC).
125.  
126. The result will be a sorted result set where the rows are arranged based on the grade in descending order. Within each grade, the rows will be further sorted based on the name in ascending order.
127.  
128. You can modify the column names and the sort order based on your specific requirements. Simply specify the desired columns in the ORDER BY clause and indicate whether you want them sorted in ascending (ASC) or descending (DESC) order.