updating-data-with-joins-in-sql

Author: daKeshra

sql-queries-5/updating-data-with-joins-in-sql/update-join-with-case.sql

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+-- update data with case case condition
+UPDATE Student 
+SET graduation_date = CASE 
+    WHEN e.semester = 'FALL' THEN '2024-12-15' 
+    WHEN e.semester = 'SPRING' THEN '2024-06-15' 
+    ELSE NULL 
+    END 
+FROM Student AS s 
+JOIN Exam AS e ON s.id = e.student_id;
+
+
+-- display outpt for SPRING semester
+SELECT * FROM Student AS s 
+JOIN Exam AS e ON e.student_id = s.id 
+WHERE e.semester = 'SPRING' 
+LIMIT 10;

sql-queries-5/updating-data-with-joins-in-sql/update-join-with-where.sql

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+-- display top 10 rows of the Student table
+SELECT * FROM Student 
+LIMIT 10;
+
+-- display top 10 result from a join of Exam
+-- and Student table
+SELECT * FROM Exam 
+JOIN Student ON Exam.student_id = Student.id 
+LIMIT 10;
+
+
+-- UPDATE JOIN with WHERE clause
+UPDATE Exam 
+SET e.grade = 'C' 
+FROM Exam AS e 
+JOIN Student AS s ON e.student_id = s.id 
+WHERE s.national_id = 123345566 AND e.grade IS NULL;
+
+
+-- confirm the output
+SELECT * FROM Exam AS e 
+JOIN Student AS s ON e.student_id = s.id 
+WHERE national_id = 123345566;