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Understand SQL, the standard query language for databases, by practicing example queries and manipulating data. Start with simple exercises to master SQL commands and enhance your database skills.
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SQL: What is it? • SQL stands for Structured Query Language. • It was originally developed in the early 1970s by IBM as a way to manipulate and retrieve data stored in IBM’s relational DBMS, System R. • It can be pronounced “Sequel” or “S-Q-L”. • With some variations, SQL is the standard query language for relational databases.
When do we use SQL? • SQL is most commonly used to retrieve data from a database. • It is also commonly used to modify data. • SQL also contains commands for creating tables and other database objects, and for maintaining data security through granting and denying privileges to users.
SQL is Intuitive • To show how easy it is to learn SQL, we’ll start out simply using examples. • We’ll review what you see in the examples in upcoming lectures.
Players Table • SELECT LastName FROM Players WHERE PlayerID = 8 • SELECT Position FROM Players WHERE LastName = ‘Schrute’ • SELECT Age FROM Players WHERE FirstName = ‘Dwight’
Answers • SELECT LastName FROM Players WHERE PlayerID = 8 • Jennings • SELECT Position FROM Players WHERE LastName = ‘Schrute’ • Left Field • SELECT Age FROM Players WHERE FirstName = ‘Dwight’ • 27
Trick Question • SELECT PlayerID FROM Players WHERE LastName = ‘Johnson’
SELECT PlayerID • FROM Players WHERE Position = 'AH'
SELECT FirstName, LastName, Age FROM Players WHERE Position = 'Pitcher'
SELECT FirstName, LastName, Age FROM Players WHERE Position = 'Pitcher'
SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE Age < 22
SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE Age < 22
SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND Age>35
SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND Age>35
SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND Age>37 OR Position='1st Base'
SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND Age>37 OR Position='1st Base'
Elements Table SELECT symbol FROM elements WHERE grp=13 AND period=4
SELECT symbol,grp,period FROM elements WHERE grp=13 OR period=4
SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND (Age>37 OR Position='1st Base') ORDER BY Age
SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND (Age>37 OR Position='1st Base') ORDER BY Age
You are the DBMS • In these exercises, you are acting like the DBMS. • All major DBMS’s have SQL interpreters. • You can submit queries like these to a database and the DBMS will find the matching results for you.
Trick Question! • SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND (Age>37 AND Position='1st Base') ORDER BY Age
SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND (Age>37 AND Position='1st Base') ORDER BY Age
SELECT * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear
SELECT * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear
SELECT * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear ASC
SELECT * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear ASC
SELECT * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear DESC
SELECT * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear DESC
SELECT Symbol, Element, AtomicNumber, AtomicMass, AtomicMass / AtomicNumber AS WeightRatio FROM Elements WHERE Grp = 4
SELECT Symbol, Element, AtomicNumber, AtomicMass, AtomicMass / AtomicNumber AS WeightRatio FROM Elements WHERE Grp = 4
SELECT TOP 1 * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear
SELECT TOP 1 * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear
SELECT TOP 1 * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear DESC
SELECT TOP 1 * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear DESC
SELECT * FROM Elements WHERE AtomicNumber BETWEEN 80 AND 90 ORDER BY AtomicNumber DESC