Day 7

Quiz

1:What is wrong with the following statement? 
DELETE * FROM customer_demo

A1: This statement should not be using the '*'. In addition, the FROM keyword is optional. The correct syntax of this statement is 
DELETE FROM customer_demo

Or

DELETE customer_demo

Remember that this would delete all the data in the table.

2:What is wrong with the following statement?
UPDATE customer_demo (
    'John', 'smith', 34)

A2: Answer: This statement mixes the UPDATE command with the INSERT command. To UPDATE values into the customer_demo table, you use the following syntax for an update: 
UPDATE customer_demoSET Fname = 'John',
    Lname = 'smith'
    age = 34

And for an insert, the following syntax would be used:

INSERT INTO customer_demo
            (Fname, Lname, Age)
       Values('John', 'smith', 34)

3:What would happen if you executed the following statement?
DELETE * from customer_demo

A3: Nothing would be deleted because this is incorrect syntax. The * is not needed in the DELETE statement.
4:Will the following SQL statement work?
INSERT INTO customer_demo
SET VALUES = 758
WHERE ITEM = 'CAR'

A4: No, this statement would not work. The syntax is incorrect. The SET clause is not part of the INSERT statement.

Exercises

1:Create a table called customers_demo with the following columns: an identity column called cust_id; fname and lname as required fields; email, which is an optional email address; and cust_new to specify whether the customer is new. The cust_new column should default to 'Y' to specify that the customer is new to the company.
A1: The following code will create the table as described: 
Create table customers_demo(
Cust_id int identity,
Fname varchar(30) not null,
Lname varchar(30) not null,
Email varchar(20) null,
Cust_new char(1) not null default 'Y')

2:Insert the following data into your table:
First Name Last NameEmailNew Customer?
JohnSmith[email protected]Y
JuliePinter N
BillBuckley[email protected]Y
SevenNine[email protected]N

A2: The following shows how to insert the specified data:
Insert customers_demo (fname, lname, email, cust_new)
    Values('John', 'Smith', '[email protected]')
Insert customers_demo (fname, lname, cust_new)
    Values('Julie', 'Pinter', 'N')
Insert customers_demo (fname, lname, email)
    Values('Bill', 'Buckley', '[email protected]')
Insert customers_demo (fname, lname, email, cust_new)
    Values('Seven', 'Nine', '[email protected]', 'N')

For email addresses that were not specified, I left them out, and let the server insert a NULL. When the new customer flag is 'Y', I left it out so that the server will insert the default value of 'Y'.

3:Try inserting values with the incorrect data types into the table. Note the errors and then insert values with correct data types into the table.
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