Sams Teach Yourself SQL in 24 Hours

Sep 9, 2005

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Workshop

The following workshop is composed of a series of quiz questions and practical exercises. The quiz questions are designed to test your overall understanding of the current material. The practical exercises are intended to afford you the opportunity to apply the concepts discussed during the current hour, as well as build upon the knowledge acquired in previous hours of study. Please take time to complete the quiz questions and exercises before continuing. Refer to Appendix C,"Answers to Quizzes and Exercises," for answers.

Quiz

Refer to the Oracle syntax covered in this hour for the following quiz questions.

Is the syntax correct for the following compound queries? If not, what would correct the syntax? Use the EMPLOYEE_TBL and the EMPLOYEE_PAY_TBL shown as follows:

`EMPLOYEE_TBL`
`EMP_ID`	`VARCHAR(9)`	`NOT NULL`,
`LAST_NAME`	`VARCHAR(15)`	`NOT NULL`,
`FIRST_NAME`	`VARCHAR(15)`	`NOT NULL`,
`MIDDLE_NAME`	`VARCHAR(15),`
`ADDRESS`	`VARCHAR(30)`	`NOT NULL`,
`CITY`	`VARCHAR(15)`	`NOT NULL`,
`STATE`	VAR`CHAR(2)`	`NOT NULL`,
`ZIP`	`INTEGER(5)`	`NOT NULL`,
`PHONE`	VAR`CHAR(10),`
`PAGER`	VAR`CHAR(10),`

CONSTRAINT EMP_PK PRIMARY KEY (EMP_ID)

`EMPLOYEE_PAY_TBL`
`EMP_ID`	`VARCHAR(9)`	`NOT NULL`,	`PRIMARY KEY`
`POSITION`	`VARCHAR(15)`	`NOT NULL`,
`DATE_HIRE`	`DATETIME`,
`PAY_RATE`	`DECIMAL(4,2)`	`NOT NULL`,
`DATE_LAST_RAISE`	`DATE`,
`SALARY`	`DECIMAL(8,2),`
`BONUS`	`DECIMAL(6,2),`

CONSTRAINT EMP_FK FOREIGN KEY (EMP_ID) 
REFERENCES EMPLOYEE_TBL (EMP_ID)

```
SELECT EMP_ID, LAST_NAME, FIRST_NAME 
FROM EMPLOYEE_TBL
UNION
SELECT EMP_ID, POSITION, DATE_HIRE
FROM EMPLOYEE_PAY_TBL;
```
This compound query does not work because the data types do not match. The EMP_ID columns match, but the LAST_NAME and FIRST_NAME data types do not match the POSITION and DATE_HIRE data types.

SELECT EMP_ID FROM EMPLOYEE_TBL 
UNION ALL
SELECT EMP_ID FROM EMPLOYEE_PAY_TBL
ORDER BY EMP_ID;

Yes, the statement is correct.

SELECT EMP_ID FROM EMPLOYEE_PAY_TBL 
INTERSECT
SELECT EMP_ID FROM EMPLOYEE_TBL
ORDER BY 1;

Yes, this compound query works.

Match the correct operator to the following statements.

Statement	Operator
Show duplicates Return only rows from the first query that match those in the second query Return no duplicates Return only rows from the first query not returned by the second	`UNION` `INTERSECT` `UNION ALL` `EXCEPT`

Statement

Operator

Show duplicates
Return only rows from the first query that match those in the second query
Return no duplicates
Return only rows from the first query not returned by the second

UNION

INTERSECT

UNION ALL

EXCEPT

Exercises

Refer to the Oracle syntax covered in this hour for the following exercises. Write your queries out by hand on a sheet of paper because MySQL does not support the operators covered in this hour. When you are finished, compare your results to mine.

Using the CUSTOMER_TBL and the ORDERS_TBL as listed:

`CUSTOMER_TBL`
`CUST_IN`	`VARCHAR(10)`	`NOT NULL`	`PRIMARY KEY`
`CUST_NAME`	`VARCHAR(30)`	`NOT NULL`,
`CUST_ADDRESS`	`VARCHAR(20)`	`NOT NULL`,
`CUST_CITY`	`VARCHAR(15)`	`NOT NULL`,
`CUST_STATE`	VAR`CHAR(2)`	`NOT NULL`,
`CUST_ZIP`	`INTEGER(5)`	`NOT NULL`,
`CUST_PHONE`	`INTEGER(10),`
`CUST_FAX`	`INTEGER(10)`

`ORDERS_TBL`
`ORD_NUM`	`VARCHAR(10)`	`NOT NULL`	`PRIMARY KEY`
`CUST_ID`	`VARCHAR(10)`	`NOT NULL`,
`PROD_ID`	`VARCHAR(10)`	`NOT NULL`,
`QTY`	`INTEGER(6)`	`NOT NULL`,
`ORD_DATE`	`DATETIME`

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