Employee-Management-Database/schema.sql at main · Royxnish/Employee-Management-Database · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
/*
===============================================================================
Project         : Employee Management Database
Author          : Nishika Roy
Database        : employee_management

Description:
A normalized Employee Management Database designed for SQL analytics,
reporting, and dashboarding.

Skills Demonstrated:
• Database Design
• Relational Modeling
• Third Normal Form (3NF)
• Primary & Foreign Keys
• Composite Keys
• Constraints
• Indexing
• Historical Tracking
• Analytical Query Optimization

===============================================================================
*/

DROP DATABASE IF EXISTS employee_management;

CREATE DATABASE employee_management;

USE employee_management;

-- ============================================================================
-- EMPLOYEES
-- ============================================================================

CREATE TABLE employees (

    emp_id INT PRIMARY KEY,

    first_name VARCHAR(50) NOT NULL,

    last_name VARCHAR(50) NOT NULL,

    gender ENUM ('M','F') NOT NULL,

    birth_date DATE NOT NULL,

    hire_date DATE NOT NULL,

    CHECK (hire_date >= birth_date)

);

-- ============================================================================
-- DEPARTMENTS
-- ============================================================================

CREATE TABLE departments (

    dept_id CHAR(4) PRIMARY KEY,

    department_name VARCHAR(50) NOT NULL UNIQUE

);

-- ============================================================================
-- EMPLOYEE DEPARTMENT HISTORY
-- ============================================================================

CREATE TABLE employee_departments (

    emp_id INT NOT NULL,

    dept_id CHAR(4) NOT NULL,

    start_date DATE NOT NULL,

    end_date DATE,

    is_current BOOLEAN NOT NULL DEFAULT TRUE,

    PRIMARY KEY (emp_id, dept_id, start_date),

    FOREIGN KEY (emp_id)
        REFERENCES employees(emp_id)
        ON DELETE CASCADE,

    FOREIGN KEY (dept_id)
        REFERENCES departments(dept_id)
        ON DELETE CASCADE,

    CHECK (
        end_date IS NULL
        OR end_date >= start_date
    )

);

-- ============================================================================
-- DEPARTMENT MANAGERS
-- ============================================================================

CREATE TABLE department_managers (

    emp_id INT NOT NULL,

    dept_id CHAR(4) NOT NULL,

    start_date DATE NOT NULL,

    end_date DATE,

    is_current BOOLEAN NOT NULL DEFAULT TRUE,

    PRIMARY KEY (emp_id, dept_id, start_date),

    FOREIGN KEY (emp_id)
        REFERENCES employees(emp_id)
        ON DELETE CASCADE,

    FOREIGN KEY (dept_id)
        REFERENCES departments(dept_id)
        ON DELETE CASCADE

);

-- ============================================================================
-- EMPLOYEE SALARY HISTORY
-- ============================================================================

CREATE TABLE salaries (

    emp_id INT NOT NULL,

    salary DECIMAL(10,2) NOT NULL,

    start_date DATE NOT NULL,

    end_date DATE,

    is_current BOOLEAN NOT NULL DEFAULT TRUE,

    PRIMARY KEY (emp_id,start_date),

    FOREIGN KEY (emp_id)
        REFERENCES employees(emp_id)
        ON DELETE CASCADE,

    CHECK (salary > 0)

);

-- ============================================================================
-- EMPLOYEE TITLE HISTORY
-- ============================================================================

CREATE TABLE employee_titles (

    emp_id INT NOT NULL,

    title VARCHAR(100) NOT NULL,

    start_date DATE NOT NULL,

    end_date DATE,

    is_current BOOLEAN NOT NULL DEFAULT TRUE,

    PRIMARY KEY (emp_id,title,start_date),

    FOREIGN KEY (emp_id)
        REFERENCES employees(emp_id)
        ON DELETE CASCADE

);

-- ============================================================================
-- INDEXES
-- ============================================================================

CREATE INDEX idx_employee_name
ON employees(last_name, first_name);

CREATE INDEX idx_department_name
ON departments(department_name);

CREATE INDEX idx_current_salary
ON salaries(is_current, salary);

CREATE INDEX idx_salary_employee
ON salaries(emp_id);

CREATE INDEX idx_current_department
ON employee_departments(is_current);

CREATE INDEX idx_department_lookup
ON employee_departments(dept_id);

CREATE INDEX idx_manager_lookup
ON department_managers(dept_id);

CREATE INDEX idx_current_title
ON employee_titles(is_current);

CREATE INDEX idx_title_lookup
ON employee_titles(title);