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Update company.tsql
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‎T-Sql/company.tsql‎

Lines changed: 365 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -167,7 +167,9 @@ VALUES (501, 3, '2023-12-15', 4.5, 1, 'Excellent performance in sales targets. G
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INSERT INTO PERFORMANCE_REVIEW(reviewId, empId, reviewDate, rating, reviewerEmpId, comments)
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VALUES (502, 6, '2023-12-16', 4.2, 1, 'Consistently meets targets. Could improve on documentation.');
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-- ========================================
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-- SELECT QUERIES
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-- ========================================
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-- Sample queries
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-- Find all employees in Sales department
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SELECT * FROM EMPLOYEE WHERE dept = 'Sales';
@@ -191,3 +193,365 @@ FROM EMPLOYEE e
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LEFT JOIN ATTENDANCE a ON e.empId = a.empId
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WHERE MONTH(a.workDate) = MONTH(GETDATE()) AND YEAR(a.workDate) = YEAR(GETDATE())
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GROUP BY e.name;
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-- ========================================
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-- ALTER TABLE / UPDATE COLUMN TYPE QUERIES
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-- ========================================
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-- Increase the size of varchar columns
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ALTER TABLE DEPARTMENT ALTER COLUMN deptName VARCHAR(50);
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ALTER TABLE DEPARTMENT ALTER COLUMN location VARCHAR(100);
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-- Change email column to accommodate longer email addresses
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ALTER TABLE EMPLOYEE ALTER COLUMN email VARCHAR(100);
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-- Expand project name and status fields
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ALTER TABLE PROJECT ALTER COLUMN projectName VARCHAR(100);
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ALTER TABLE PROJECT ALTER COLUMN status VARCHAR(25);
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-- Increase performance review comments field
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ALTER TABLE PERFORMANCE_REVIEW ALTER COLUMN comments VARCHAR(1000);
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-- Add new columns to existing tables
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ALTER TABLE EMPLOYEE ADD isActive BIT DEFAULT 1;
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ALTER TABLE EMPLOYEE ADD terminationDate DATE NULL;
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ALTER TABLE PROJECT ADD projectManager INT NULL;
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ALTER TABLE PROJECT ADD FOREIGN KEY (projectManager) REFERENCES EMPLOYEE(empId);
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ALTER TABLE DEPARTMENT ADD budget DECIMAL(15,2) NULL;
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-- For SQL Server, to change data type of a column with data:
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-- First, create a new column with the desired type
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ALTER TABLE PROJECT_ASSIGNMENT ADD hoursAllocatedNew DECIMAL(7,2);
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-- Copy data from old column to new column
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UPDATE PROJECT_ASSIGNMENT SET hoursAllocatedNew = hoursAllocated;
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-- Drop the old column
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ALTER TABLE PROJECT_ASSIGNMENT DROP COLUMN hoursAllocated;
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-- Rename the new column to the original name
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EXEC sp_rename 'PROJECT_ASSIGNMENT.hoursAllocatedNew', 'hoursAllocated', 'COLUMN';
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-- ========================================
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-- COMPLEX SELECT QUERIES WITH CTEs
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-- ========================================
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-- 1. Employee Hierarchy with Recursive CTE
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WITH EmployeeHierarchy AS (
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-- Anchor member: Top-level managers
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SELECT empId, name, managerId, jobTitle, 0 as Level
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FROM EMPLOYEE
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WHERE managerId IS NULL
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UNION ALL
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-- Recursive member: Employees under managers
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SELECT e.empId, e.name, e.managerId, e.jobTitle, eh.Level + 1
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FROM EMPLOYEE e
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INNER JOIN EmployeeHierarchy eh ON e.managerId = eh.empId
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)
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SELECT empId, name, jobTitle, Level,
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REPLICATE(' ', Level) + name AS HierarchicalName
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FROM EmployeeHierarchy
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ORDER BY Level, name;
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-- 2. Department Performance Analysis with Multiple CTEs
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WITH DeptSalary AS (
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SELECT d.deptId, d.deptName,
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AVG(s.amount) as avgSalary,
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MIN(s.amount) as minSalary,
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MAX(s.amount) as maxSalary,
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COUNT(e.empId) as empCount
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FROM DEPARTMENT d
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JOIN EMPLOYEE e ON d.deptId = e.deptId
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JOIN SALARY s ON e.empId = s.empId
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GROUP BY d.deptId, d.deptName
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),
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DeptProjects AS (
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SELECT d.deptId,
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COUNT(DISTINCT p.projectId) as projectCount,
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SUM(p.budget) as totalBudget,
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AVG(p.budget) as avgProjectBudget
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FROM DEPARTMENT d
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LEFT JOIN PROJECT p ON d.deptId = p.deptId
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GROUP BY d.deptId
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)
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SELECT ds.deptName,
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ds.empCount,
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ds.avgSalary,
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ds.minSalary,
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ds.maxSalary,
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COALESCE(dp.projectCount, 0) as projectCount,
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COALESCE(dp.totalBudget, 0) as totalProjectBudget,
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COALESCE(dp.avgProjectBudget, 0) as avgProjectBudget
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FROM DeptSalary ds
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LEFT JOIN DeptProjects dp ON ds.deptId = dp.deptId
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ORDER BY ds.avgSalary DESC;
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-- 3. Employee Workload Analysis
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WITH EmployeeProjects AS (
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SELECT e.empId, e.name, e.deptId,
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COUNT(pa.projectId) as projectCount,
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SUM(pa.hoursAllocated) as totalHours
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FROM EMPLOYEE e
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LEFT JOIN PROJECT_ASSIGNMENT pa ON e.empId = pa.empId
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GROUP BY e.empId, e.name, e.deptId
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),
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ProjectDetails AS (
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SELECT pa.empId,
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STRING_AGG(p.projectName, ', ') as projectList
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FROM PROJECT_ASSIGNMENT pa
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JOIN PROJECT p ON pa.projectId = p.projectId
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GROUP BY pa.empId
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)
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SELECT ep.name,
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d.deptName,
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ep.projectCount,
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ep.totalHours,
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pd.projectList,
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CASE
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WHEN ep.totalHours > 40 THEN 'Overallocated'
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WHEN ep.totalHours BETWEEN 30 AND 40 THEN 'Fully Allocated'
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WHEN ep.totalHours BETWEEN 15 AND 29 THEN 'Partially Allocated'
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ELSE 'Underallocated'
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END as AllocationStatus
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FROM EmployeeProjects ep
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JOIN DEPARTMENT d ON ep.deptId = d.deptId
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LEFT JOIN ProjectDetails pd ON ep.empId = pd.empId
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ORDER BY ep.totalHours DESC;
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-- 4. Salary Ranking within Departments
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WITH SalaryRanking AS (
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SELECT e.empId, e.name, d.deptName, s.amount,
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RANK() OVER (PARTITION BY d.deptId ORDER BY s.amount DESC) as salaryRank,
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DENSE_RANK() OVER (PARTITION BY d.deptId ORDER BY s.amount DESC) as denseRank,
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ROW_NUMBER() OVER (PARTITION BY d.deptId ORDER BY s.amount DESC) as rowNum,
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PERCENT_RANK() OVER (PARTITION BY d.deptId ORDER BY s.amount DESC) as percentRank
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FROM EMPLOYEE e
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JOIN DEPARTMENT d ON e.deptId = d.deptId
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JOIN SALARY s ON e.empId = s.empId
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)
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SELECT name, deptName, amount,
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salaryRank,
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CASE
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WHEN percentRank <= 0.25 THEN 'Top 25%'
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WHEN percentRank <= 0.50 THEN 'Top 50%'
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WHEN percentRank <= 0.75 THEN 'Top 75%'
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ELSE 'Bottom 25%'
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END as SalaryPercentile
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FROM SalaryRanking
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ORDER BY deptName, salaryRank;
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-- 5. Project Timeline Analysis
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WITH ProjectStatus AS (
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SELECT projectId, projectName,
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startDate, endDate, budget, status,
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DATEDIFF(day, startDate, endDate) as durationDays,
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DATEDIFF(day, startDate, GETDATE()) as daysElapsed,
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CASE
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WHEN endDate < GETDATE() AND status != 'Completed' THEN 'Overdue'
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WHEN endDate >= GETDATE() AND status = 'In Progress' THEN 'On Track'
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WHEN status = 'Completed' THEN 'Completed'
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ELSE 'Not Started'
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END as ProjectHealth
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FROM PROJECT
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),
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ProjectTeam AS (
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SELECT p.projectId,
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COUNT(DISTINCT pa.empId) as teamSize,
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SUM(pa.hoursAllocated) as totalAllocatedHours
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FROM PROJECT p
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LEFT JOIN PROJECT_ASSIGNMENT pa ON p.projectId = pa.projectId
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GROUP BY p.projectId
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)
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SELECT ps.projectName,
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ps.status,
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ps.ProjectHealth,
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ps.durationDays,
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ps.daysElapsed,
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CAST(ps.daysElapsed * 100.0 / NULLIF(ps.durationDays, 0) AS DECIMAL(5,2)) as PercentComplete,
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ps.budget,
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pt.teamSize,
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pt.totalAllocatedHours
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FROM ProjectStatus ps
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LEFT JOIN ProjectTeam pt ON ps.projectId = pt.projectId
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ORDER BY ps.ProjectHealth DESC, ps.endDate;
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-- 6. Employee Tenure and Salary Growth Analysis
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WITH EmployeeTenure AS (
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SELECT empId, name, hireDate,
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DATEDIFF(year, hireDate, GETDATE()) as yearsOfService,
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DATEDIFF(month, hireDate, GETDATE()) as monthsOfService
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FROM EMPLOYEE
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),
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SalaryHistory AS (
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SELECT et.empId, et.name, et.yearsOfService,
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s.amount as currentSalary,
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s.amount / NULLIF(et.yearsOfService, 0) as avgYearlyIncrease
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FROM EmployeeTenure et
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JOIN SALARY s ON et.empId = s.empId
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)
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SELECT name, yearsOfService, currentSalary,
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COALESCE(avgYearlyIncrease, currentSalary) as avgYearlyIncrease,
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CASE
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WHEN yearsOfService < 2 THEN 'New Employee'
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WHEN yearsOfService BETWEEN 2 AND 5 THEN 'Mid-Level'
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ELSE 'Senior Employee'
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END as TenureCategory
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FROM SalaryHistory
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ORDER BY yearsOfService DESC;
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-- 7. Department Cross-Analysis
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WITH DepartmentMetrics AS (
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SELECT d.deptId, d.deptName,
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COUNT(DISTINCT e.empId) as employeeCount,
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COUNT(DISTINCT p.projectId) as projectCount,
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COALESCE(SUM(p.budget), 0) as totalProjectBudget,
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AVG(s.amount) as avgSalary
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FROM DEPARTMENT d
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LEFT JOIN EMPLOYEE e ON d.deptId = e.deptId
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LEFT JOIN PROJECT p ON d.deptId = p.deptId
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LEFT JOIN SALARY s ON e.empId = s.empId
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GROUP BY d.deptId, d.deptName
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),
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DepartmentEfficiency AS (
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SELECT deptId,
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CASE
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WHEN employeeCount > 0 THEN totalProjectBudget / employeeCount
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ELSE 0
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END as budgetPerEmployee,
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CASE
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WHEN projectCount > 0 THEN employeeCount * 1.0 / projectCount
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ELSE 0
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END as employeesPerProject
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FROM DepartmentMetrics
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)
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SELECT dm.deptName,
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dm.employeeCount,
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dm.projectCount,
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dm.totalProjectBudget,
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dm.avgSalary,
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de.budgetPerEmployee,
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de.employeesPerProject
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FROM DepartmentMetrics dm
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JOIN DepartmentEfficiency de ON dm.deptId = de.deptId
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ORDER BY dm.totalProjectBudget DESC;
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-- 8. Performance Review Insights
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WITH ReviewStats AS (
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SELECT e.empId, e.name, e.deptId,
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COUNT(pr.reviewId) as reviewCount,
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AVG(pr.rating) as avgRating,
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MIN(pr.rating) as minRating,
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MAX(pr.rating) as maxRating
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FROM EMPLOYEE e
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LEFT JOIN PERFORMANCE_REVIEW pr ON e.empId = pr.empId
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GROUP BY e.empId, e.name, e.deptId
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),
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DeptAvgRating AS (
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SELECT deptId,
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AVG(avgRating) as deptAvgRating
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FROM ReviewStats
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WHERE avgRating IS NOT NULL
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GROUP BY deptId
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)
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SELECT rs.name,
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d.deptName,
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rs.reviewCount,
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rs.avgRating,
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dar.deptAvgRating,
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CASE
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WHEN rs.avgRating > dar.deptAvgRating THEN 'Above Department Average'
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WHEN rs.avgRating = dar.deptAvgRating THEN 'At Department Average'
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WHEN rs.avgRating < dar.deptAvgRating THEN 'Below Department Average'
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ELSE 'No Reviews'
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END as PerformanceLevel
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FROM ReviewStats rs
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JOIN DEPARTMENT d ON rs.deptId = d.deptId
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LEFT JOIN DeptAvgRating dar ON rs.deptId = dar.deptId
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ORDER BY CASE WHEN rs.avgRating IS NULL THEN 1 ELSE 0 END, rs.avgRating DESC;
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-- 9. Attendance Pattern Analysis
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WITH AttendanceStats AS (
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SELECT empId,
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COUNT(*) as daysPresent,
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AVG(DATEDIFF(hour, timeIn, timeOut)) as avgHoursWorked,
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MIN(timeIn) as earliestArrival,
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MAX(timeOut) as latestDeparture
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FROM ATTENDANCE
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WHERE workDate >= DATEADD(month, -1, GETDATE())
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GROUP BY empId
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),
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EmployeeAttendance AS (
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SELECT e.empId, e.name, d.deptName,
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COALESCE(a.daysPresent, 0) as daysPresent,
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COALESCE(a.avgHoursWorked, 0) as avgHoursWorked,
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a.earliestArrival,
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a.latestDeparture
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FROM EMPLOYEE e
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JOIN DEPARTMENT d ON e.deptId = d.deptId
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LEFT JOIN AttendanceStats a ON e.empId = a.empId
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)
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SELECT name, deptName, daysPresent, avgHoursWorked,
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FORMAT(earliestArrival, 'HH:mm') as earliestArrival,
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FORMAT(latestDeparture, 'HH:mm') as latestDeparture,
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CASE
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WHEN avgHoursWorked >= 9 THEN 'Overtime Worker'
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WHEN avgHoursWorked BETWEEN 7.5 AND 9 THEN 'Regular Hours'
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WHEN avgHoursWorked > 0 THEN 'Part Time'
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ELSE 'No Recent Attendance'
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END as WorkPattern
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FROM EmployeeAttendance
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ORDER BY avgHoursWorked DESC;
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-- 10. Comprehensive Employee Dashboard
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WITH EmployeeSummary AS (
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SELECT e.empId, e.name, e.jobTitle, d.deptName,
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s.amount as salary,
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DATEDIFF(year, e.hireDate, GETDATE()) as yearsOfService
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FROM EMPLOYEE e
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JOIN DEPARTMENT d ON e.deptId = d.deptId
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LEFT JOIN SALARY s ON e.empId = s.empId
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),
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ProjectSummary AS (
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SELECT pa.empId,
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COUNT(DISTINCT pa.projectId) as activeProjects,
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SUM(pa.hoursAllocated) as totalHours
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FROM PROJECT_ASSIGNMENT pa
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JOIN PROJECT p ON pa.projectId = p.projectId
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WHERE p.status = 'In Progress'
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GROUP BY pa.empId
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),
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ReviewSummary AS (
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SELECT empId,
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AVG(rating) as avgRating,
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MAX(reviewDate) as lastReviewDate
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FROM PERFORMANCE_REVIEW
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GROUP BY empId
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)
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SELECT es.name,
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es.jobTitle,
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es.deptName,
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es.salary,
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es.yearsOfService,
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COALESCE(ps.activeProjects, 0) as activeProjects,
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COALESCE(ps.totalHours, 0) as projectHours,
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rs.avgRating,
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rs.lastReviewDate,
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CASE
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WHEN rs.lastReviewDate < DATEADD(year, -1, GETDATE()) OR rs.lastReviewDate IS NULL
551+
THEN 'Review Overdue'
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ELSE 'Review Current'
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END as reviewStatus
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FROM EmployeeSummary es
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LEFT JOIN ProjectSummary ps ON es.empId = ps.empId
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LEFT JOIN ReviewSummary rs ON es.empId = rs.empId
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ORDER BY es.name;

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