Getting to Know SQL. © Jim Hope 2004 All Rights Reserved Data Manipulation SELECT statement INSERT...

Getting to Know SQL

© Jim Hope 2004 All Rights Reserved

Data Manipulation• SELECT statement • INSERT INTO statement • UPDATE statement • DELETE statement • UNION operation


Data Definition• CREATE TABLE statement • CREATE INDEX statement • ALTER TABLE statement • CONSTRAINT clause • DROP statement • SELECT... INTO statement


1 SELECT• SELECT * • FROM People ;

Means: Select all the fields (*) for all rows from the table called People


2 Specify Fields• SELECT LastName, FirstName• FROM People ;

Means: Select the fields (LastName and FirstName) for all rows from the table called People


3a Setting the Scope• SELECT LastName, FirstName, Score• FROM People• WHERE Score >=250

Means: Select the fields (LastName, FirstName, Score) for only rows where the Score is greater than or equal to 250


3b Setting the Scope• SELECT LastName, FirstName, Score• FROM People• WHERE Score >=250 OR Score

<=100Means: Select the fields (LastName and

FirstName, Score) for only rows where the Score is greater than or equal to 250 or the Score is less than or equal to 100


4a Setting the Order• SELECT LastName, FirstName• FROM People• ORDER BY LastName ;

Means: Select the fields (LastName and FirstName) for all rows from the table called People, in alphabetical (ascending) order by the values in the LastName field.


4b Setting the Order• SELECT LastName, FirstName• FROM People• ORDER BY LastName, FirstName ;

Means: Select the fields (LastName and FirstName) for all rows from the table called People, in alphabetical (ascending) order by the values in the LastName field. If there are duplicates – use the FirstName (ascending)


4c Setting the Order• SELECT LastName, FirstName, Score• FROM People• ORDER BY Score DESC, LastName,

FirstName;Means: Select the fields (LastName and

FirstName) for all rows from the table called People, in (descending) order by the values in the Score field.


4d Setting the Order – you try• SELECT LastName, FirstName, Score• FROM People• ORDER BY Score DESC

What would you do if you wanted to see rows with duplicate Scores presented alphabetically by player


5a Putting things together• SELECT LastName, FirstName, Score• FROM People• WHERE Score >=290 or Score <=100• ORDER BY Score DESC

What is this doing?


5b Putting more things together• SELECT LastName, FirstName, Score,

City• FROM People• WHERE (Score >=290 or Score <=100)

and City <> "Surrey"• ORDER BY Score DESCWhat is this doing


5c Putting more things together• SELECT LastName, FirstName, Score, City• FROM People• WHERE

(Score >=290 or Score <=100) and City <> "Surrey"

• and City <> "Burnaby"• ORDER BY Score DESCWhat is this doing, and what else would you add?


5d Putting more things together• SELECT LastName, FirstName, Score, City• FROM People• WHERE

(Score >=290 and City <> "Surrey") or (Score <=100 and City <> "New York")

• ORDER BY Score DESCWhat is this doing


5e Scope with IN• SELECT LastName, FirstName, Score• FROM People• WHERE LastName

IN ("Bundy", "Simpson", "Petrie");

(much better than… • WHERE LastName = “Bundy” OR

LastName = “Simpson” ORLastName = “Petrie”


5f Whatnot• SELECT LastName, FirstName, Score• FROM People• WHERE LastName

NOT IN ("Bundy", "Simpson", "Petrie");• Try this one


6a Counting• SELECT count(*)• FROM People


6b Counting• SELECT count(*)• FROM People• WHERE Score <100


7 Wildcards• SELECT LastName, FirstName• FROM People• WHERE LastName like 'b*'

or• MS Access

(WHERE LastName like 'b*')


8a You can do math?• SELECT LastName, FirstName,

Score, Score +10 as BigScore• FROM People• ORDER BY Score DESC


9a Create an Alias with CONCAT• SELECT

CONCAT(LastName,", ",FirstName) AS FullName

• FROM PEOPLE• ORDER BY LastName, FirstNameQuestion: who is [Null]?• --- alternate form (MS Access)• SELECT LastName +", " + FirstName as FullName• FROM People


9b Who was NULL?

• SELECT LastName, FirstName, CONCAT(LastName,", ",FirstName)

AS FullName• FROM PEOPLE• ORDER BY LastName, FirstName• This answers the question – who is [NULL] in the previous example


10a Max & Min• SELECT MAX (Score)• FROM People

• SELECT MIN (Score)• FROM People


10b Simple Stats and Aliases• SELECT • MIN(Score) as `Lowest Score`,• ROUND(AVG(Score),2) as Average, • MAX(Score) as `Highest Score`,• ROUND(STD(Score),2)

as `Standard Deviation`• FROM People


10c Limiting Rows Returned• SELECT LastName, FirstName, Score• FROM People• ORDER BY Score DESC• LIMIT 1

Who are we missing here?


10c Max again• SELECT LastName, FirstName, Score• FROM People• WHERE Score =

(SELECT MAX(Score) FROM People);

This is a Subquery Version 4.1 Alpha


11 Keeping things DISTINCTTry This…• SELECT City• FROM PeopleThen Try• SELECT DISTINCT City• FROM People


12a More than one tableTry • SELECT `Team Name` FROM TeamThen Try• SELECT `Team Name` ,

LastName, FirstNameFROM Team, People

This creates a Cartesian Product!


12b More than one table• SELECT `Team Name` , LastName,

FirstName • FROM Team, People• WHERE

Team.Team=People.Team• ORDER BY `Team Name` ,

LastName, FirstName


12c Using Join• SELECT `Team Name` , LastName,

FirstName • FROM

Team INNER JOIN People ON Team.Team=People.Team

• ORDER BY `Team Name` , LastName, FirstName

Last two lines no longer required• FROM People, Team• WHERE People.Team=Team.Team


12c Using Join• SELECT LastName,

FirstName, Score, `Show Name`

• FROM People INNER JOIN `Show` ON People.Show = Show.Show ;


12d Using Left Join• SELECT LastName,


• FROM People Left JOIN `Show` ON People.Show = Show.Show ;


12e Using Right Join• SELECT LastName,


• FROM People Right JOIN `Show` ON People.Show = Show.Show ;


13a Group By – putting it together• SELECT `Team Name`,

ROUND(AVG(Score),2) AS `Average`

• FROM People,Team WHERE People.Team=Team.Team

• GROUP BY Team.`Team Name`


13b Inner Join and Group By• SELECT `Team Name`,

ROUND(AVG(Score),2) AS `Average`

• FROM Team INNER JOIN People ON People.Team=Team.Team

• GROUP BY Team.`Team Name


14 SELECT INTO (new table)• SELECT Team.`Team Name`,

AVG(Score) AS `Average`• INTO TeamSummary• FROM People INNER JOIN Team ON

People.Team = Team.Team• GROUP BY Team.`Team Name`Sorry – you don’t have permissions to

do this on the netpub instance of MySQL

Jim Hope

SELECT `Team Name`, avg(Score) as AvgScoreFROM People INNER JOIN team ON People.Team = team.Teamgroup by `Team Name`


16 SELECT with IF• SELECT LastName, • IF(FirstName IS NULL, Description,

FirstName) as Salutation, Score • FROM People, Titles• WHERE People.t = Titles.Titles


That’s enough of that

Getting to Know SQL. © Jim Hope 2004 All Rights Reserved Data Manipulation SELECT statement INSERT...

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