Chapter 7 Only Question 1 And 7 Need To Be Completed

Chapter 7only Question 1 And 7 Need To Be Completed For Chapter 7 Th

Write the SQL code to create the table structure for a table named EMP_1. This table is a subset of the EMPLOYEE table. The basic EMP_1 table structure is summarized in the following table. (Note that the JOB_CODE is the FK to JOB.)

Write the SQL code to change the job code to 501 for the person whose employee number (EMP_NUM) is 107. After you have completed the task, examine the results and then reset the job code to its original value.

Write the SQL code to delete the row for William Smithfield, who was hired on June 22, 2004, and whose job code is 500. (Hint: Use logical operators to include all of the information given in this problem.)

Write the SQL code that will restore the data to its original status; that is, the table should contain the data that existed before you made the changes in Problems 5 and 6.

Paper For Above instruction

The objective of this paper is to demonstrate a comprehensive understanding of SQL commands related to table creation, data modification, deletion, and data restoration, as applied to a specific scenario involving employee data management. The scenario involves working with a subset of an employee database, performing specific modifications to employee records, and then restoring the data to its original state. This exercise not only emphasizes practical SQL skills but also highlights the importance of data integrity and the use of transactional operations to ensure consistent database states.

These operations, including creating new tables, updating existing records, deleting specific entries, and restoring data, are fundamental tasks in database management. They require precise SQL coding skills and an understanding of relational database principles. This paper will outline the necessary steps and SQL queries to accomplish each task, illustrating their application in a real-world context.

Introduction

SQL (Structured Query Language) is the backbone of managing relational databases. It allows users to create new tables, insert and update data, delete records, and restore data as required. Effective data management necessitates a thorough understanding of these commands, particularly in scenarios where data must be temporarily modified and then restored to its original state for consistency and accuracy. The scenario presented involves a subset of an employee database, focusing on specific records pertinent to the tasks outlined.

Creating the EMP_1 Table

The first requirement is to create a new table called EMP_1, which is a subset of the EMPLOYEE table. This entails defining a table structure that captures essential employee information while considering referential integrity with the JOB table through the JOB_CODE foreign key. The table should include key columns such as EMP_NUM, NAME, JOB_CODE, HIRE_DATE, and others relevant to the subset needed for the operations. An example SQL statement would be:

CREATE TABLE EMP_1 AS

SELECT EMP_NUM, NAME, JOB_CODE, HIRE_DATE, OTHER_COLUMNS


FROM EMPLOYEE


WHERE CONDITIONS;

Adjustments may be needed depending on specific subset requirements, but the above provides a foundational structure for creating a subset table.

Modifying Employee Records

In Problem 5, the task is to update the job code for the employee with EMP_NUM 107 to 501. The SQL statement would be:

UPDATE EMP_1

SET JOB_CODE = 501


WHERE EMP_NUM = 107;

After executing the update, it is crucial to verify the change and then revert it to the original value. To do this, one must have stored the original job code prior to modification. The revert operation might look like:

UPDATE EMP_1

SET JOB_CODE = [original_value]


WHERE EMP_NUM = 107;

This back-and-forth ensures data consistency during testing operations.

Deleting a Record

Problem 6 involves deleting the record for William Smithfield, hired on June 22, 2004, with a specific job code of 500. Using logical operators such as AND helps ensure precise targeting:

DELETE FROM EMP_1

WHERE NAME = 'William Smithfield'


AND HIRE_DATE = '2004-06-22'


AND JOB_CODE = 500;

This operation removes the designated employee record based on multiple conditions. Ensuring these conditions are correct is vital to prevent unintentional data deletion.

Restoring Original Data

Finally, Problem 7 demands restoring the data to its initial state before modifications. This can be achieved by executing delete and insert operations for the modified records or by using a backup table that stored the original data earlier. For instance, if a backup of original data exists in a table called EMP_OLD, restoring data involves:

DELETE FROM EMP_1

WHERE EMP_NUM IN ([list of modified EMP_NUMs]);


INSERT INTO EMP_1


SELECT * FROM EMP_OLD


WHERE EMP_NUM IN ([list of modified EMP_NUMs]);

This approach ensures that the EMP_1 table reverts to its initial data state, reflecting the original dataset before updates or deletions.

Conclusion

Mastering SQL commands for creating, updating, deleting, and restoring data is essential for effective database management. The scenario illustrated demonstrates these operations' practical application, emphasizing the importance of careful transaction management, data integrity, and the ability to revert changes when necessary. Proper use of these SQL techniques ensures reliable, consistent, and accurate management of employee data within relational databases.

References

  • Elmasri, R., & Navathe, S. B. (2015). Fundamentals of Database Systems. Pearson Education.
  • Rob, P., & Coronel, C. (2007). Database Systems: Design, Implementation, and Management. Course Technology.
  • Kroenke, D. M., & Auer, D. J. (2018). Database Concepts. Pearson.
  • Date, C. J. (2012). Database Design and Relational Theory. O'Reilly Media.
  • Pratt, R., & Andrychuk, M. (2018). SQL: The Complete Reference. McGraw-Hill Education.
  • Coronel, C., & Morris, S. (2015). Database Systems: Design, Implementation, & Management. Cengage Learning.
  • Hart, J. (2019). SQL for Beginners: Learn SQL in 1 Day. CreateSpace Independent Publishing Platform.
  • Ozsu, M. T., & Valduriez, P. (2011). Principles of Distributed Database Systems. Springer.
  • Hernandez, M. J. (2013). Database Design for Mere Mortals. Addison-Wesley.
  • Fayyad, U., Piatetsky-Shapiro, G., & Smyth, P. (1996). From Data Mining to Knowledge Discovery in Databases. AI Magazine, 17(3), 37-54.

Related Assignments