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Chapter 5 Data Manipulation and Transaction Control

Chapter 5 Data Manipulation and Transaction Control. Jason C. H. Chen , Ph.D. Professor of MIS School of Business Gonzaga University Spokane, WA 99258 USA chen@jepson.gonzaga.edu. Objectives. Use the INSERT command to add a record to an existing table

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Chapter 5 Data Manipulation and Transaction Control

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  1. Chapter 5Data Manipulation and Transaction Control Jason C. H. Chen, Ph.D. Professor of MIS School of Business Gonzaga University Spokane, WA 99258 USA chen@jepson.gonzaga.edu

  2. Objectives • Use the INSERT command to add a record to an existing table • Manage virtual columns in data manipulations • Use quotes in data values • Use a subquery to copy records from an existing table • Use the UPDATE command to modify the existing rows of a table • Use substitution variables with an UPDATE command

  3. Objectives (continued) • Delete records • Manage transactions with transaction control commands COMMIT, ROLLBACK, and SAVEPOINT • Differentiate between a shared lock and an exclusive lock • Use the SELECT…FOR UPDATE command to create a shared lock

  4. Refresh the Database • 1. Run the following script file • Start c:\oradata\chapter5\JLDB_Build_5.sql

  5. SQL Components ORACLE (SQL Components) DDL D.B. DML DCL (Create Table structure and insert database)

  6. DDL Commands • Used to create and modify the structure of database objects • CREATE • ALTER • DROP • DDL commands execute as soon as they are issued, and do not need to be explicitly saved

  7. DML Commands • Used to insert, view, and modify database data • INSERT • UPDATE • DELETE • SELECT • DML commands need to be explicitly saved or rolled back • COMMIT • ROLLBACK • SAVEPOINT

  8. DCL Commands • Used to control the privileges and security of database objects • GRANT • REVOKE

  9. Security -Granting Table Privileges • Security is the prevention of unauthorized access to the database. Within an organization, the database administrator determines the types of access various users need for the database. • Some users might be able to retrieve and update data in the database. Other users might be able to retrieve any data from the database but not make any changes to it. Still other users might be able to access only a portion of the database.

  10. INSERT Command • Used to add rows to existing tables • Identify the table in the INSERT INTO clause • Specify data in the VALUES clause • Can only add one row at a time to a table • Enclose nonnumeric data in single quotes • If a column list is not provided, a value must be assigned to each column in the table Figure 5-2 Syntax of the INSERT command

  11. Your Turn … • Re-run a new script file not including acctmanager table SQL> start c:\oradata\chapter5\JLDB_Build_5.sql • You now are able to • create acctmanager table, and • insert new rows (data value) into the acctmanager table

  12. The acctmanaer Table Creation CREATE TABLE acctmanager (amid CHAR(4), amfirst VARCHAR2(12) NOT NULL, amlast VARCHAR2(12) NOT NULL, amedate DATE DEFAULT SYSDATE, amsal NUMBER(8,2), amcomm NUMBER(7,2) DEFAULT 0, region CHAR(2), CONSTRAINT acctmanager_amid_pk PRIMARY KEY (amid), CONSTRAINT acctmanager_region_ck CHECK (region IN ('N', 'NW', 'NE', 'S', 'SE', 'SW', 'W', 'E'))); Figure 5-1 The ACCTMANAGER table creation

  13. Inserting New Records Table 5-2 Data for Account Managers Type the following commands: -- chapter 5, Figure 5-3; p. 140 INSERT INTO acctmanager VALUES ('T500', 'NICK', 'TAYLOR', '05-SEP-09', 42000, 3500, 'NE'); SELECT * FROM acctmanager;

  14. Inserting New Records (Your Turn …) -- chapter 5, Figure 5-5; p. 142 INSERT INTO acctmanager (amid, amfirst, amlast, amedate, amsal, amcomm) VALUES ('L500', 'MANDY', 'LOPEZ', '01-OCT-09', 47000, 1500); SELECT * FROM acctmanager; -- chapter 5, Figure 5-9; p. 143 INSERT INTO acctmanager (amid, amfirst, amlast, amedate, amsal, amcomm, region) VALUES ('J500', 'Sammie', 'Jones', ‘DEFAULT’, 39500, 2000, 'NW'); --[ERROR OCCURS – why?] --[ (NO ' ')] INSERT INTO acctmanager (amid, amfirst, amlast, amedate, amsal, amcomm, region) VALUES ('J500', 'Sammie', 'Jones', DEFAULT, 39500, 2000, 'NW'); -- or INSERT INTO acctmanager (amid, amfirst, amlast, amsal, amcomm, region) VALUES ('J500', 'Sammie', 'Jones', 39500, 2000, 'NW'); -- chapter 5, Figure 5-10; p. 144 SELECT * FROM acctmanager;

  15. INSERT Command Examples No Column List Figure 5-3 The INSERT command for Nick Taylor Column List Figure 5-9 Use an INSERT statement that applies a DEFAULT column option

  16. Three Ways Inserting NULL Value • Omit column name from INSERT INTO clause column list • Substitute two single quotation marks • Use NULL keyword Run script file on SQL PLUS -- chapter 5, Figure 5-5; p. 142 INSERT INTO acctmanager (amid, amfirst, amlast, amedate, amsal, amcomm) VALUES ('L500', 'MANDY', 'LOPEZ', '01-OCT-09', 47000, 1500); INSERT INTO acctmanager VALUES ('L500', 'MANDY', 'LOPEZ', '01-OCT-09', 47000, 1500, ''); INSERT INTO acctmanager VALUES ('L500', 'MANDY', 'LOPEZ', '01-OCT-09', 47000, 1500, NULL); Figure 5-6 The INSERT INTO command for Mandy Lopez NULL value input NULL value input

  17. Three Ways Inserting “SYSDATE” Value(Note: errors in the text book; p.143) • Insert the current date ‘SYSDATE’ in the Amedate column • Use the keyword ‘DEFAULT’ for the column value in the VALUES clause • Include a column list in the INSERT INTO clause that omits the Amedate column -- chapter 5, Figure 5-7; 5-8; p. 143 -- note that no ‘ ‘ is required, or, error occurred INSERT INTO acctmanager (amid, amfirst, amlast, amedate, amsal, amcomm, region) VALUES ('J500', 'Sammie', 'Jones', SYSDATE, 39500, 2000, 'NW'); -- or INSERT INTO acctmanager (amid, amfirst, amlast, amedate, amsal, amcomm, region) VALUES ('J500', 'Sammie', 'Jones', DEFAULT, 39500, 2000, 'NW'); -- chapter 5, Figure 5-9; p. 143 INSERT INTO acctmanager (amid, amfirst, amlast, amsal, amcomm, region) VALUES ('J500', 'Sammie', 'Jones', 39500, 2000, 'NW');

  18. Handling Virtual Columns Create an Amearn column as indicated in Fig. 5-11 (also in Fig. 3-2; p. 64. The column is called “virtual column” (or derived/computed), which is generated from other column values. -- chapter 5, Figure 5-10; p. 144 SELECT * FROM acctmanager; -- chapter 5, Figure 5-11; p. 144 ALTER TABLE acctmanager ADD (amearn AS (amsal + amcomm)); -- chapter 5, Figure 5-12; p. 145 SELECT * FROM acctmanager;

  19. Handling Virtual Columns (cont.) -- chapter 5, Figure 5-12; p. 145 SELECT * FROM acctmanager; virtual (derived) column

  20. Manage Virtual Column Input Figure 5-13 Error caused by using a virtual column in an INSERT statement

  21. Handling Single Quotes in an INSERT Value -- chapter 5, Figure 5-15; p. 146 INSERT INTO acctmanager (amid, amfirst, smlast, amsal, amcomm, region) VALUES ('M500', 'Peg', 'O'hara', 46000, 2000, 'SW'); -- chapter 5, Figure 5-16; p. 147 INSERT INTO acctmanager (amid, amfirst, smlast, amsal, amcomm, region) VALUES ('M500', 'Peg', 'O''hara', 46000, 2000, 'SW'); -- chapter 5, Figure 5-17; p. 147 SELECT * FROM acctmanager;

  22. Constraint Violations • When you add or modify table data, the data is checked for compliance with any applicable constraints • You should practice all examples (more commands such as UPDATE on p.150-157))

  23. Inserting Data from an Existing Table • Substitute subquery for VALUES clause • Note: make sure you have re-run a new script file (i.e., JLDB_Build_5.sql) with acctbonus table created. Subquery Figure 5-19 INSERT INTO command with a subquery -- chapter 5, Figure 5-20; p. 149 SELECT * FROM acctbonus;

  24. Modifying Existing Rows • Modify rows using UPDATE command • Use UPDATE command to: • Add values to an existing row (replace NULL values) • Change existing values • UPDATE clause identifies table • SET clause identifies column(s) being changed and new value(s) • Optional WHERE clause specifies row(s) to be changed – if omitted, all rows will be updated!

  25. UPDATE Command Syntax Figure 5-21 Syntax of the UPDATE command UPDATE Command Examples -- chapter 5, Figure 5-22; p. 151 UPDATE acctmanager SET amedate = '01-AUG-09' WHERE amid = 'J500'; -- chapter 5, Figure 5-23; p. 151 UPDATE acctmanager SET region = 'W' WHERE region IN ('NE', 'NW'); -- chapter 5, Figure 5-24; p. 152 UPDATE acctmanager SET amedate = '10-OCT-09', region = 'S' WHERE amid = 'L500'; SELECT * FROM acctmanager;

  26. Substitution Variables • Prompts user for value • Identified by ampersand (&) preceding variable name • Can be used to create interactive scripts -- chapter 5, Figure 5-26; p. 153 UPDATE customers SET region = 'W' WHERE state = 'CA'; -- chapter 5, Figure 5-27; p. 154 UPDATE customers SET region = '&Region' WHERE state = '&State';

  27. Substitution Variable Example Figure 5-27 Prompt for substitution variable input

  28. Figure 5-28 Verify UPDATE results

  29. Deleting Rows • DELETE command removes a row from a table WHERE clause determines which row(s) are removed Figure 5-30 DELETE command to remove a row from the ACCTMANAGER table

  30. DELETE Command – Omitting WHERE Clause • Omitting WHERE clause removes all rows • Example below removes all rows from the acctmanager table Figure 5-32 DELETE command without the WHERE clause

  31. Transaction Control Statements • Results of data manipulation language (DML) are not permanently updated to a table until explicit or implicit COMMIT occurs • Transaction control statements can: • Commit data through COMMIT command • Undo data changes through ROLLBACK command

  32. COMMIT Command • Explicit COMMIT occurs by executing COMMIT; • Implicit COMMIT occurs when DDL command is executed or user properly exits system • Permanently updates table(s) and allows other users to view changes

  33. Transaction Control Example A B C SAVEPOINT ALEX; UPPLER CASE ROLLBACK TO ONE; Figure 5-34 Establishing a SAVEPOINT

  34. Transaction Control Example A B C SAVEPOINT ALEX; ROLLBACK TO ONE; Figure 5-34 Establishing a SAVEPOINT

  35. Transaction Control Example (continued) Figure 5-35 Database before using ROLLBACK TO ONE; -- chapter 5, Figure 5-36; p. 161 ROLLBACK TO ONE; Only undo DML actions after SAVEPOINT Figure 5-37 Undo changes to SAVEPOINT ONE

  36. Transaction Control Example (continued) Figure 5-37 Database before using ROLLBACK -- chapter 5, Figure 5-38; p. 162 ROLLBACK; Figure 5-39 Verify the ROLLBACK results

  37. Practice all the examples in the text. • A Script file is available on the Bb (file name: Ch5Queries.sql) • After completing all examples, do the HW.

  38. Homework - Hands-On Assignments Email me with one attachment (Oracle_ch5_Spool_Lname_Fname.) to: chen@jepson.gonzaga.edu with subject title of Bmis441-01_Oracle_ch45(or Bmis441-02_Oracle_ch5) Read and Practice all examples on Chapters 5 • 1. Run the script files (in the folder \oradata\chapter5\): JLDB_Build_5.sql • 2. Read Oracle assignment and create a script file Oracle_ch5_Lname_Fname.sql for questions (#1 to #5, #9,#10; p.170) on “Hands-on Assignments”. . • 3. Execute and test one problem at a time and make sure they are all running successfully. • 4. When you done, spool the script files (see next slide for spooling instructions) and email the file (Oracle_ch5_Spool_Lname_Fname.txt) to me by the midnight before the next class.

  39. How to Spool your Script and Output Files After you tested the script file of Oracle_ch5_Lname_Fname.sql successfully, follow the instructions below to spool both script and output files: Step 0. Run the following script file from SQL*Plus (since you have created JLDB tables) • Start c:\oradata\chapter5\JLDB_Build_5.sql • 1. type the following on SQL> • Spool c:\oradata\Oracle_ch5_Spool_Lname_Fname.txt (make sure your name is entered) • 2. open Oracle_ch5_Lname_Fname.sql that you already tested • 3. copy and paste all the SQL commands (including all comments) to the SQL*PLUS • 4. type Spool Off on the SQL> The output should contain your personal information, all SQL commands and their solution on the .txt file and saved in C: drive (oradata\ folder) Email me with the spooled file (.txt) with attachment to: chen@jepson.gonzaga.edu with subject title of Bmis441-01_Oracle_ch5 (or Bmis441-02_Oracle_ch5)

  40. Summary • Data manipulation language (DML) includes the INSERT, UPDATE, DELETE, COMMIT, and ROLLBACK commands • The INSERT INTO command is used to add new rows to an existing table • The column list specified in the INSERT INTO clause must match the order of data entered in the VALUES clause • A virtual column must be ignored in all DML actions because the database system generates this column value automatically • You can use a NULL value in an INSERT INTO command by including the keyword NULL, omitting the column from the column list of the INSERT INTO clause, or entering two single quotes (without a space) in the position of the NULL value

  41. Summary (continued) • To assign a DEFAULT option value, a column must be excluded from the column list in an INSERT statement or the keyword DEFAULT must be included as the value for the column • In a DML statement, two single quotes together must be used to represent a single quote in a value • If rows are copied from a table and entered in an existing table by using a subquery in the INSERT INTO command, the VALUES clause must be omitted because it’s irrelevant • You can change the contents of a row or group of rows with the UPDATE command • You can use substitution variables to allow you to execute the same command several times with different data values

  42. Summary (continued) • DML operations aren’t stored permanently in a table until a COMMIT command is issued implicitly or explicitly • A transaction consists of a set of DML operations committed as a block • Uncommitted DML operations can be undone by issuing the ROLLBACK command • A SAVEPOINT serves as a marker for a point in a transaction and allows rolling back only a portion of the transaction • Use the DELETE command to remove records from a table; if the WHERE clause is omitted, all rows in the table are deleted • Table locks can be used to prevent users from mistakenly overwriting changes made by other users

  43. Summary (continued) • Table locks can be in SHARE mode or EXCLUSIVE mode • EXCLUSIVE mode is the most restrictive table lock and prevents any other user from placing any locks on the same table • A lock is released when a transaction control statement is issued, a DDL statement is executed, or the user exits the system by using the EXIT command • SHARE mode allows other users to place shared locks on other portions of the table, but it prevents users from placing an exclusive lock on the table • The SELECT . . . FOR UPDATE command can be used to place a shared lock for a specific row or rows; the lock isn’t released unless a DDL command is issued or the user exits the system

  44. End of Chapter 5

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