Merge pull request #347 from yadavan88/alias-queries

Alias AS query

Author: davidmartinezbarua

sql-queries-11/as-alias/as-alias.sql

@@ -0,0 +1,18 @@
+SELECT name, gpa AS grade_point_average 
+FROM Student;
+
+SELECT name, graduation_date - enrollment_date AS study_duration_in_days 
+FROM Student;
+
+-- ONLY in SQL Server since - operator not supported for date
+SELECT name, DATEDIFF(DAY, enrollment_date, graduation_date) AS study_duration_in_days
+FROM Student;
+
+SELECT s.name,e.course_id,e.grade 
+FROM Student AS s 
+JOIN Exam AS e ON s.id = e.student_id 
+WHERE e.grade IS NOT NULL;
+
+SELECT s.name,s.gpa 
+FROM Student AS s, (SELECT AVG(gpa) AS overall_avg_gpa FROM Student) AS avg_gpa_subquery 
+WHERE s.gpa > avg_gpa_subquery.overall_avg_gpa;