ISM 4212 Lab

Creating DB Tables

02

copyright Lars Paul Linden 2007

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Lab Overview

Last Week: Introduction to the SQL Server DBMS• Creating Databases• Moving Databases

This Week: Creating DB Tables

Next Week: Introduction to SQL SELECT Statements

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Today’s Agenda

CREATE tables and DROP tables (GUI and SQL) Fields (the columns), including setting field data types

More about creating tables NULL / NOT NULL IDENTITY keyword PRIMARY KEY DEFAULT values

Setting table properties Create a diagram

Multi-page diagrams Using the diagram as an editing tool for DB objects

Relationships between tables

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Create Tablesand

Drop Tables

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Two Ways of Creating Tables

Graphical User Interface’s (GUI) “New Table” form Execute SQL in a Query Pane

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The GUI’s “New Table” form Using SQL Server Manager Studio, open the your database in

the Object Explorer Expand the database to see the “Tables” folder Right click on “Tables” and select “New Table…” In the pane that opens, enter a “Column Name”, hit tab, use

the drop down to specify a “Data Type”, and check “Allow Nulls” depending on your design

Complete cells with column metadata Repeat until all of your columns are specified When done, “X” out the pane, respond “Yes” Finally, in the “Choose Name” pop-up, type in the name of

your table, and click “OK”

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Having Created It,Display Your Table

Using SQL Server Manager Studio In the Object Explorer, open the your database Expand the database to see the “Tables” folder Expand the “Tables” folder to see the name of your

table Right click on the name of your table and select

“Modify”

Note: select “Open Table” to see the table’s data

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basic CREATE TABLE syntax

CREATE TABLE Products(

ProductID INT, ProductName CHAR(20), Price MONEY

)

Commas betweencolumn specifications

Parenthesis aroundColumn specifications

Notice how each linehas a field nameand that field’s data type

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Another wayto create a table with SQL

Open a Query Pane Open the “Template Explorer” Under “Table”, select “Create Table” Replace the <xxxxxxx> as needed

an example of the syntax is on the next slide And, of course, execute

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Drop a Table (GUI)

Using SQL Server Manager Studio, open the your database in the Object Explorer

Expand the database to see the “Tables” folder Expand the “Tables” folder to see the name of your

table Right click on the name of your table and select

“Delete” Click on “Yes” to confirm

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Drop a Table (SQL)

# Make sure you are using the correct database

DROP TABLE YourTableName

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Setting table properties

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table properties

In Object Explorer right-click on the table name Select “Properties”

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More about creating DB tables

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Look at an existing table

In “Northwind” Open the “Shippers” table

Using Rgt-Click “Modify” Note the following:

A. Allow NullsB. Identify SpecificationC. Primary Key iconD. Default values (not shown)

Now we covers these four topics…

CA

B

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CREATE TABLEwith NULL or NOT NULLCREATE TABLE Products2(

ProductID INT NOT NULL, Name CHAR(20) NOT NULL, Price MONEY NOT NULL,Description CHAR(100) NULL

)

After executed, you can viewthe table and check what you createdfor the Description field:

A.

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What is the impactof the NOT NULL?

In a few weeks, in the lab when we INSERT data into a table,

we’ll see that if a field is marked as NOT NULL then data must be inserted into that field or an error message will result.

That is, there is a constraint on that field in the table Any row of data in that table, must have data in any NOT NULL field.

A.

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CREATE TABLEwith an IDENTITY

What does the IDENTITY do? Automatically increments on insert Only one per table By itself, not guaranteed unique You can turn it on and off

Now, see the syntax…

B.

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CREATE TABLEwith an IDENTITY

CREATE TABLE Products3(ProductID INT IDENTITY NOT NULL, Name CHAR(20) NOT NULL, Price MONEY NOT NULL,Description CHAR(100) NULL

)After executed, you can viewthe table and checkthe result at the bottomunder “Column Properties”:

B.

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What is the impactof the IDENTITY?

In a few weeks, in the lab when we INSERT data into a table,

we’ll see that if a field has an IDENTITY then the “seed” automatically increments and is inserted into that field of the row when the row is inserted into the table.

This is perfect for some Primary Keys

B.

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One little trick to knowabout the IDENTITY

You can specify how the identity is going to behave: IDENTITY (<seed>, <increment>)

CREATE TABLE Products4

(

ProductID INT IDENTITY(10,5) NOT NULL,

Name CHAR(20) NOT NULL,

Price MONEY NOT NULL,

Description CHAR(100) NULL

)

B.

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One little trick to knowabout the IDENTITY

When viewing the table,in the “Column Properties” section,expand the “Identity Specification”

The detailsof the Identity

B.(con’t)

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CREATE TABLEwith a PRIMARY KEY

CREATE TABLE Categories(

CategoryID int NOT NULL,CategoryName nvarchar(15) NOT NULL,Description ntext NULL,CONSTRAINT PK_Categories PRIMARY KEY (CategoryID)

)

C.

the nameof thisconstraint

the typeof constraint

the fieldthat is the PK

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CREATE TABLEwith a PRIMARY KEY

After executed, you can viewthe table and see a checkfor the PK icon:

C.

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What is the impactof a PRIMARY KEY?

For starters, it is a constraint “Enforces uniqueness for the purpose of identifying a

row.”-Turley, page 331

C.

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Default values When a new row is inserted into this table, if the

“State” field is not specified in the insert statement, then the system automatically add the default field of ‘FL’.

CREATE TABLE Locations

(

LocationID INT IDENTITY NOT NULL,

LocationName CHAR(20) NOT NULL,

State CHAR(2) NOT NULL DEFAULT 'FL'

)

D.

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Evidence of the Default valuesD.

Select the field

then look below

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Diagram

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Create a diagram

Using SQL Server Manager Studio, Open the your database in the Object Explorer Expand the database to see the “Database Diagrams”

folder Right click on “Database Diagrams and select “New

Database Diagram” Add Tables To save, right click on the tab of the pane and enter a

name in the “Choose Name” pop-up

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Miscellaneous Diagram Operations

On menu, select “Database Diagram” and then “Arrange Tables”

To zoom, right click on the background and select “Zoom”

To change the appearance of a table, right click on a table and select “Table View” and then a new selection

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From a diagram, you can alter your tables

In the diagram, right click on the table Choose a selection, for example, “Insert Column” When you are all done, make sure you save the

diagram by right-clicking on the tab and selecting “Save…”

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Help with Multi-page diagrams

With the diagram open… Right click on the background and select “View Page Breaks”

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Save Your Diagram

Right-click on the tab, and select save Give your diagram a name The diagram is then available in the Object Explorer

under “Database Diagrams”

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Create a RelationshipBetween Two Tables

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Inspecta One-to-Many Relationship

First, lets look at an example In Northwind… Focus on just the Categories table and the Products table Notice that the Categories table has a CategoryID and that the

Products table has a CategoryID There exists a relationship between these two tables Specifically, Products.CategoryID is a Foreign Key that

references the Categories.CategoryID which is a Primary Key

(con’t on next slide)

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Inspecta One-to-Many Relationship

(con’t from previous slide)

To find evidence of this relationship… Open Northwind’s “Products” table Right-click on the background and select “Relationships” In the “Foreign Key Relationships” pop-up window, find the

“Selected Relationships” area that lists the existing relationships

Highlight the “FK_Products_Categories” and then expand the part of the window where it says “Tables and Columns Specification” … this will show the tables and attributes.

(con’t on next slide)

(con’t)

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Inspecta One-to-Many Relationship

(con’t)

Lists the detailsof the relationship

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Creating a One-to-Many Relationship (GUI)

First, create two tables that can be used in the exampleCREATE TABLE MyCategories(

CategoryID int IDENTITY(1,1) NOT NULL,CategoryName nvarchar(15) NOT NULL,Description ntext NULL,CONSTRAINT PK_MyCategories PRIMARY KEY (CategoryID)

)CREATE TABLE MyProducts(

ProductID INT, ProductName CHAR(20), Price MONEY,CategoryID INT NOT NULL

) (con’t)

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Creating a One-to-Many Relationship (GUI)

Now create the relationship, where the MyProducts.CategoryID is the FK and the MyCategories.CategoryID is the PK

From the Object Explorer, right click and “modify” the MyProducts table

Right click on background and select “Relationships” Click “Add” Under “Identity” where it says (name), enter the name of the

relationships (e.g. FK_MyProducts_MyCategories) Under “Tables and Columns Specification” click the button that

has the ellipsis (“…”) Select a table and field for the Primary Key and the Foreign Key “OK” to save and “Close” to exit “Foreign Key Relationship”

pop-up

(con’t)

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Creating a One-to-Many Relationship (SQL)

First, create two tables that can be used in the exampleCREATE TABLE MyCategories2(

CategoryID int IDENTITY(1,1) NOT NULL,CategoryName nvarchar(15) NOT NULL,Description ntext NULL,CONSTRAINT PK_MyCategories2 PRIMARY KEY (CategoryID)

)CREATE TABLE MyProducts2(

ProductID INT, ProductName CHAR(20), Price MONEY,CategoryID INT NOT NULL

FOREIGN KEY REFERENCES MyCategories2 (CategoryID))

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Bonus

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Ctrl+K, Ctrl+C to Comment SQLCtrl+K, Ctrl+U to Uncomment SQL

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Another wayto see your table’s metadata

EXEC sp_help YourTableName

Note: the “sp_help” is a stored procedure that comes with the installation. We’ll learn more about stored procedures in a few weeks.

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Next Week

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Next Topic

1. Introduction to SQL SELECT Statements

including the following important SQL keywords:

WHERE ORDER BY AS

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To Do List

1. Practice

2. Read Ch. 3 (pp. 41-52): Statements

3. Read Ch. 4 (pp. 79-89): JOINs