added files for maintaining and transactions

Author: John McGaughey

maintaining-sql-eddb.sql

@@ -0,0 +1,64 @@
+-- DELETE STATEMENT
+DELETE 
+	FROM Student
+	WHERE SAT <=900;
+
+-- UPDATE statement
+update Student set
+	GPA = GPA - 0.1
+	where MajorId = (select id from Major where Description like '%Math%');
+
+update Student set
+	GPA = GPA + 0.1
+	where majorid = (select id from Major where Description like '%Math%');
+
+select * 
+	from Student
+	where majorid = (select id from Major where Description like '%Math%');
+
+-- INSERT statement
+INSERT Student															-- primary cant be listed if sql generates it 
+	(Firstname, Lastname, StateCode, SAT, GPA, MajorId)					-- SAT/MajorId can be null 
+	VALUES
+	('John', 'McGaughey', 'KY', '1250', '2.8', '7'),
+	('Justin', 'McGaughey', 'KY', '1000', '3.2', null);
+
+DELETE from Student
+	Where Lastname like ('%McGaughey%');
+
+select Firstname as 'First Name', Lastname as 'Last Name', StateCode as 'State', sat,	gpa, Description as 'Major' 
+	from Student s
+	join major m
+		on s.MajorId = m.Id
+	where Lastname like ('%McG%');
+
+UPDATE Student set
+	MajorId = (select id from Major where Description like ('%Education%'))
+	where Lastname like ('%McG%');
+
+-- Create Major Underwater Basket Weaving
+insert Major 
+	(Code, Description, MinSAT)
+	VALUES
+	('BSKT', 'Underwater Basket Weaving', 12);
+
+Select * from Major
+	order by Description;
+
+-- remove major Finance, put all students in Finance into the Chad Major Underwater Basket Weaving
+update Student set
+	MajorId = (select id from Major where code = 'BSKT')
+	where MajorId = (select id from Major where Description like ('%General Studies%'));
+
+-- check all students now underwater
+select Firstname as 'First Name', Lastname as 'Last Name', StateCode as 'State', sat,	gpa, Description as 'Major' 
+	from Student s
+	join major m
+		on s.MajorId = m.Id
+	WHERE s.MajorId = (select id from Major where Description like ('%Under%'));
+
+-- delete major general studies
+delete major
+	where ID = (select id from Major where Description = 'General studies')
+
+select * from major;

practice-query-EdDb.sql

@@ -112,3 +112,20 @@ select statecode as 'State', COUNT(*) as 'Number of Students'
 select *
 	from Student
 	where GPA = (select MAX(gpa) from Student);
+
+-- CONCAT combines multiple tables into 1 string
+select CONCAT(Lastname,', ', Firstname) as 'name', GPA, SAT
+	from Student
+	order by Lastname;
+
+-- FORMAT can change the format of a table to show currency
+-- IN SALESDB
+select name, FORMAT(sales, 'C')
+	from customers;
+
+-- ISNULL - will change null to a specified string
+select CONCAT(s.firstname, ' ', s.Lastname) as 'Name', ISNULL(Description, 'Undeclared') as 'Major'
+	from Student s
+	left join Major m
+		on s.MajorId = m.Id
+	order by s.Lastname;

transactions-sql-eddb.sql

@@ -0,0 +1,10 @@
+-- TRANSACTIONS
+begin transaction;
+
+update major set 
+	Description = 'To be deleted' 
+	where id = 8;
+
+select * from Major;
+
+rollback;						-- this will revert the changes to description