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Oracle_ch3 HW (#7 & 8) required SQL> --7. SQL> CREATE TABLE book_pricing (id, cost, retail, category) 2 AS (SELECT isbn, cost, retail, category 3 FROM books); Table created. SQL> --7b.(version 2) SQL> SQL> DROP TABLE book_pricing CASCADE CONSTRAINTS; Table dropped. required SQL> SQL> CREATE TABLE book_pricing 2 AS (SELECT isbn as id, cost, retail, category 3 FROM books); Table created. Dr. Chen, Oracle Database System (Oracle) 1 SQL> --8. SQL> ALTER TABLE book_pricing 2 SET UNUSED (category); Table altered. SQL> -- use one of the following commands to verify SQL> Required (verify) SQL> --8a SQL> DESCRIBE book_pricing; Name Null? ----------------------------------------- -------ID COST Required (verify) RETAIL SQL> --8b SQL> SELECT * FROM book_pricing; ID COST RETAIL ---------- ---------- ---------1059831198 18.75 30.95 0401140733 14.2 22 4981341710 37.8 59.95 8843172113 31.4 55.95 3437212490 12.5 19.95 3957136468 47.25 75.95 1915762492 21.8 25 9959789321 37.9 54.5 2491748320 48 89.95 0299282519 19 28.75 8117949391 5.32 8.95 Dr. Chen, Oracle Database System (Oracle) the result Type ---------------------------VARCHAR2(10) NUMBER(5,2) NUMBER(5,2) ID COST RETAIL ---------- ---------- ---------0132149871 17.85 29.95 9247381001 15.4 31.95 2147428890 21.85 39.95 14 rows selected. 2 What will we study today? Data … Dr. Chen, Oracle Database System (Oracle) … Integrity How to achieve it? Referential Integrity (Constraints) 3 Chapter 4 Constraints Jason C. H. Chen, Ph.D. Professor of MIS School of Business Gonzaga University Spokane, WA 99258 USA [email protected] Dr. Chen, Oracle Database System (Oracle) 4 Objectives • Explain the purpose of constraints in a table • Distinguish among PRIMARY KEY, FOREIGN KEY, UNIQUE, CHECK, and NOT NULL constraints and the appropriate use for each constraint • Understand how constraints can be created when creating a table or modifying an existing table • Distinguish between creating constraints at the column level and table level Dr. Chen, Oracle Database System (Oracle) 5 Objectives (continued) • Create PRIMARY KEY constraints for a single column and a composite primary key (cpk) • Create a FOREIGN KEY constraint • Create a UNIQUE constraint • Create a CHECK constraint • Create a NOT NULL constraint using the ALTER TABLE…MODIFY command • Include constraints during table creation • Use DISABLE and ENABLE commands • Use the DROP command Dr. Chen, Oracle Database System (Oracle) 6 Referential Integrity Q2: Can we “delete” customers#5 if orders#1 is still in the database? Why? customers pk Customers#5 pk orders#1 customer# 1001 … 1005 1020 orders Order# 1000 … 1003 1012 LastName MORALES … GIRARD FALAH Referred NULL NULL NULL Region SE … NW NE fk customer# 1005 1001 1007 … ShipZip ShipCost 98114 … 32328 49002 2.00 … 4.00 6.00 Q1: Can we “insert/create” orders#1 if customers#5 is not created? Why? Dr. Chen, Oracle Database System (Oracle) 7 Referential Integrity • Move to JLDB_Referential_Integrity.pptx file Dr. Chen, Oracle Database System (Oracle) 8 Refresh the Database • 1. Create a new folder on c:\ as follows: c:\oradata\chapter4 • 2. Go to Blackboard and download data files from Oracle chapter4 and save under c:\oradata\chapter4\ • 3. Run the following script file – Start c:\oradata\chapter4\JLDB_Build_4.sql Dr. Chen, Oracle Database System (Oracle) 9 Type the following SQL commands -- chapter 4, Figure 4-5; p. 108 INSERT INTO customers (customer#, lastname, firstname, region) VALUES (1020, 'PADDY', 'JACK', 'NE'); --extra INSERT command INSERT INTO orders (order#, customer#, orderdate) VALUES (1021, 1021, '06-APR-09'); -- DELETE command DELETE FROM customers WHERE customer# = 1005; Dr. Chen, Oracle Database System (Oracle) 10 Constraint Checked with Data Input Figure 4-5 Insert a row to test the constraint Dr. Chen, Oracle Database System (Oracle) What cause the problem? 11 Using the FOREIGN KEY Constraint Referential Integrity customers pk pk customer# 1001 … 1005 1020 orders Order# 1000 … 1003 1012 LastName MORALES … GIRARD FALAH Referred NULL NULL NULL Region SE … NW NE fk customer# 1005 1001 1007 … ShipZip ShipCost 98114 … 32328 49002 2.00 … 4.00 6.00 RULES: 1. You can’t add/insert a record to TABLE- (or the table with fk, e.g., orders) unless there is a corresponding record in TABLE-1 (or the table with pk). 2. You can’t delete a record in TABLE-1 (or the table with pk, e.g., customers) if there is a record in TABLE- (or the table with fk). Order of entering data into the database: customers orders Order of deleting data from the database: orders customers 12 Dr. Chen, Oracle Database System (Oracle) Review from Last Class What are the three rules of naming table and field? What are the three (total of four) required information that should be described for each field? 1. Name (saved in “UPPER” case in the D.B.) 2. Type 3. Size 4. Constraint L Dr. Chen, Oracle Database System (Oracle) 13 What is a Constraint? • A rule used to enforce business rules, practices, and policies • A rule used to ensure accuracy and integrity of data • A mechanism used to protect – the relationship between data within an Oracle table, or – the correspondence between data in two different tables. – For example, the state entered must be one of the 50 states in the U.S. Dr. Chen, Oracle Database System (Oracle) 14 Types of Constraints • Integrity constraints: define primary and foreign keys • Value constraints: define specific data values or data ranges that must be inserted into columns and whether values must be unique or not NULL • Table constraint: restricts the data value with respect to all other values in the table • Field (column) constraint: limits the value that can be placed in a specific field, irrespective of values that exist in other table records Dr. Chen, Oracle Database System (Oracle) 15 I. Naming conventions for constraints <tablename>_<fieldname>_<constraint id> Where <constraint id> is: • pk PRIMARY KEY • fk REFERENCES <tablename> (pk) • ck CHECK <condition to be checked> (note that cc stands for CHECK CONDITION) • nn NOT NULL • uk UNIQUE e.g., s_id NUMBER (6) CONSTRAINT student_s_id_pk PRIMARY KEY; Dr. Chen, Oracle Database System (Oracle) 16 Integrity Constraints • Define primary key fields • Specify foreign keys and their corresponding table and column references • Specify composite keys Dr. Chen, Oracle Database System (Oracle) 17 Creating a Table CREATE TABLE tablename (fieldname1 data_type (size) [CONSTRAINT constraint_name constraint_type], fieldname2 data_type (size), … [CONSTRAINT constraint_name constraint_type,] …); Dr. Chen, Oracle Database System (Oracle) 18 Creating Constraints • When – During table creation – After table creation, by modifying the existing table • How – Column level approach – Table level approach Dr. Chen, Oracle Database System (Oracle) 19 Creating Constraints at the Column Level • If a constraint is being created at the column level, the constraint applies to the column specified Figure 4-1 Syntax for creating a column-level constraint Creating Constraints at the Table Level • Approach can be used to create any constraint type after all table field definitions are completed except NOT NULL • Required if constraint is based on multiple columns Figure 4-2 Syntax for creating a table-level constraint Dr. Chen, Oracle Database System (Oracle) 20 pk CUSTOMERS Customer# LastName FirstName Address City NUMBER(4) VARCHAR2(10) VARCHAR2 (10) VARCHAR2 (20) VARCHAR2(12) VARCHAR 2(2) pk fk State Zip Referred Region Email VARCHAR2 (5) NUMBER( 4) CHAR(2) VARCHAR2( 30) ORDERS Order# Customer# OrderDate ShipDate ShipStreet ShipCity ShipState ShipZip ShipCost NUMBER(4) NUMBER(4) DATE DATE VARCHAR2(18) VARCHAR2(15) VARCHAR2(2) NUMBER(4) NUMBER(4,2) CREATE TABLE Customers (Customer# NUMBER(4), LastName VARCHAR2(10) NOT NULL, FirstName VARCHAR2(10) NOT NULL, Address VARCHAR2(20), City VARCHAR2(12), State VARCHAR2(2), Zip VARCHAR2(5), Optional Referred NUMBER(4), (variable name) Region CHAR(2), Email VARCHAR2(30), CONSTRAINT customers_customer#_pk PRIMARY KEY(customer#), CONSTRAINT customers_region_ck CHECK (region IN ('N', 'NW', 'NE', 'S', 'SE', 'SW', 'W', 'E')) ); Dr. Chen, Oracle Database System (Oracle) 21 Qs • Q: How to display (describe) the table structure that you just created of “customers” table? DESCRIBE customers; • A: _______________________ • Q: Any constraint(s) displayed? case is sensitive NO! • A: ____ • Q: How to display them? (UPPER case) Why? • A:_SELECT constraint_name FROM user_constraints WHERE table_name=‘CUSTOMERS’; Dr. Chen, Oracle Database System (Oracle) 22 pk CUSTOMERS Customer# LastName FirstName Address City NUMBER(4) VARCHAR2(10) VARCHAR2 (10) VARCHAR2 (20) VARCHAR2(12) VARCHAR 2(2) pk fk State Zip Referred Region Email VARCHAR2 (5) NUMBER( 4) CHAR(2) VARCHAR2( 30) ORDERS Order# Customer# OrderDate ShipDate ShipStreet ShipCity ShipState ShipZip ShipCost NUMBER(4) NUMBER(4) DATE DATE VARCHAR2(18) VARCHAR2(15) VARCHAR2(2) NUMBER(4) NUMBER(4,2) CREATE TABLE Orders (Order# NUMBER(4), Customer# NUMBER(4), OrderDate DATE NOT NULL, ShipDate DATE, ShipStreet VARCHAR2(18), ShipCity VARCHAR2(15), Optional ShipState VARCHAR2(2), (variable name) ShipZip VARCHAR2(5), ShipCost NUMBER(4,2), CONSTRAINT orders_order#_pk PRIMARY KEY(order#), CONSTRAINT orders_customer#_fk FOREIGN KEY (customer#) REFERENCES customers(customer#)); Dr. Chen, Oracle Database System (Oracle) 23 How to define ‘composite” key? pk ORDERS Order# Customer# OrderDate ShipDate ShipStreet ShipCity ShipState ShipZip ShipCost NUMBER(4) NUMBER(4) DATE DATE VARCHAR2(18) VARCHAR2(15) VARCHAR2(2) NUMBER(4) NUMBER(4,2) pk BOOKS ISBN Title PubDate PubID Cost Retail Discount Category VARCHAR2(10) VARCHAR2(30) DATE NUMBER(2) NUMBER(5,2) NUMBER(5,2) NUMBER(4,2) VARCHAR2(12) fk Order# NUMBER(4) cpk Item# NUMBER(2) fk ORDERITEMS ISBN VARCHAR2(10) Quantity NUMBER(3) PaidEach NUMBER(5,2) CREATE TABLE ORDERITEMS ( Order# NUMBER(4), Item# NUMBER(2), Optional ISBN VARCHAR2(10), Quantity NUMBER(3) NOT NULL, (variable name) PaidEach NUMBER(5,2) NOT NULL, CONSTRAINT orderitems_order#item#_pk PRIMARY KEY (order#, item#), CONSTRAINT orderitems_order#_fk FOREIGN KEY (order#) REFERENCES orders (order#) , CONSTRAINT orderitems_isbn_fk FOREIGN KEY (isbn) REFERENCES books (isbn) , CONSTRAINT oderitems_quantity_ck CHECK (quantity > 0) ); Dr. Chen, Oracle Database System (Oracle) 24 Your Job • You need to study and understand all CREATE TABLE SQL commands in JLDB_Build_4.sql Dr. Chen, Oracle Database System (Oracle) 25 Enforcement of Constraints • All constraints are enforced at the table level • If a data value violates a constraint, the entire row is rejected Dr. Chen, Oracle Database System (Oracle) 26 Constraint Types Table 4-1 Constraint types Dr. Chen, Oracle Database System (Oracle) 27 Your Turn … Dr. Chen, Oracle Database System (Oracle) 28 Primary Key Constraints Syntax: CONSTRAINT constraint_name PRIMARY KEY Create a table with the following information: 1. Name of the table: students 2. Fields: s_id number with 6 digits and is a primary key, s_name character with 30 chars, s_class with 2 chars, s_dob with DATE SQL> CREATE TABLE students 2 (s_id NUMBER(6) CONSTRAINT students_s_id_pk PRIMARY KEY, 3 s_name VARCHAR2(30), 4 s_class CHAR(2), 5 s_dob DATE); Dr. Chen, Oracle Database System (Oracle) 29 Primary Key Constraints (cont.) at the Column-Level SQL> CREATE TABLE students 2 (s_id NUMBER(6) CONSTRAINT students_s_id_pk PRIMARY KEY, 3 s_name VARCHAR2(30), 4 s_class CHAR(2), 5 s_dob DATE); at the Table-Level Practice: Type in one of the command. SQL> CREATE TABLE students 2 (s_id NUMBER(6), 3 s_name VARCHAR2(30), 4 s_class CHAR(2), 5 s_dob DATE, 6 CONSTRAINT students_s_id_pk PRIMARY KEY (s_id)); Dr. Chen, Oracle Database System (Oracle) 30 Your Job • Read the rest of powerpoint slides and practice all examples • Skip to another practice example with THREE new tables Dr. Chen, Oracle Database System (Oracle) 31 Adding Constraints to Existing Tables • Constraints are added to an existing table with the ALTER TABLE command • Add a NOT NULL constraint using MODIFY clause • All other constraints are added using ADD clause Dr. Chen, Oracle Database System (Oracle) 32 Using the PRIMARY KEY Constraint • Ensures that columns do not contain duplicate or NULL values • Only one per table is allowed Figure 4-3 Syntax of the ALTER TABLE command to add a PRIMARY KEY constraint Dr. Chen, Oracle Database System (Oracle) 33 Drop Contraint ALTER TABLE orderitems DROP CONSTRAINT orderitems_order#item#_pk PRIMARY KEY (order#, item#); Dr. Chen, Oracle Database System (Oracle) 34 Deletion of Foreign Key Values • You cannot delete a value in a parent table referenced by a row in a child table • Use ON DELETE CASCADE keywords when creating FOREIGN KEY constraint – it automatically deletes a parent row when the row in a child table is deleted Dr. Chen, Oracle Database System (Oracle) 35 Practice … • Let’s try to create additional tables – JustLee Books would like to create some new tables to store office equipment inventory data. EQUIP DEPT DeptID Dname Fax EquipID Edesc Purchdate Rating DeptID EtypeID ETYPES EtypeID Etypename Figure 4-26 E-R model for equipment tables Dr. Chen, Oracle Database System (Oracle) 36 Including Constraints during Table Creation EQUIP pk DEPT pk EquipID DeptID Dname Fax fk Edesc Purchdate Rating DeptID EtypeID fk • Each department name must be unique. • Each department must be assigned a name . • • • • • pk ETYPES EtypeID Etypename unique NOT NULL Each equipment type name must be unique unique Each equipment type must be assigned a name. NOT NULL Each equipment item must be assigned a valid department. If an equipment item is assigned a type, it must be a valid type. Valid rating values for equipment are A, B, and C. ck Dr. Chen, Oracle Database System (Oracle) 37 DEPT table creation -- chapter 4, Figure 4-27; p. 122 CREATE TABLE dept (deptid NUMBER(2), dname VARCHAR2(20) NOT NULL, fax VARCHAR2(12), CONSTRAINT dept_deptid_pk PRIMARY KEY (deptid), CONSTRAINT dept_dname_uk UNIQUE (dname) ); • Each department name must be unique. unique • Each department must be assigned a name . NOT NULL Dr. Chen, Oracle Database System (Oracle) 38 What is the main difference on the following “CREATE TABLE” statements? Constraints are defined at the table-level -- chapter 4, Figure 4-27; p. 122 CREATE TABLE dept (deptid NUMBER(2), dname VARCHAR2(20) NOT NULL, fax VARCHAR2(12), CONSTRAINT dept_deptid_pk PRIMARY KEY (deptid), CONSTRAINT dept_dname_uk UNIQUE (dname) ); Constraints are defined at the column-level -- chapter 4, Figure 4-30; p. 124 CREATE TABLE dept (deptid NUMBER(2) CONSTRAINT dept_deptid_pk PRIMARY KEY, dname VARCHAR2(20) NOT NULL CONSTRAINT dept_dname_uk UNIQUE, fax VARCHAR2(12)); Dr. Chen, Oracle Database System (Oracle) 39 • Each equipment type name must be unique -- chapter 4, Figure 4-28; p. 123 • Each equipment type must be assigned a name. CREATE TABLE etypes (etypeid NUMBER(2), etypename VARCHAR2(20) NOT NULL, CONSTRAINT etypes_etypeid_pk PRIMARY KEY (etypeid), CONSTRAINT etypes_etypename_uk UNIQUE (etypename) ); -- chapter 4, Figure 4-29; p. 123 CREATE TABLE equip • Each equipment item must be assigned a valid department. (equipid NUMBER(3), • If an equipment item is assigned a type, it must be a valid type. edesc VARCHAR2(30), purchdate DATE, • Valid rating values for equipment are A, B, and C. rating CHAR(1), deptid NUMBER(2) NOT NULL, etypeid NUMBER(2), CONSTRAINT equip_equipid_pk PRIMARY KEY (equipid), CONSTRAINT equip_deptid_fk FOREIGN KEY (deptid) REFERENCES dept (dept_id), CONSTRAINT equip_etypeid_fk FOREIGN KEY (etypeid) REFERENCES etypes (etypeid), CONSTRAINT equip_rating_ck CHECK (rating IN ('A', 'B', 'C', 'D')) ); Dr. Chen, Oracle Database System (Oracle) 40 • HW!! • Practice all the examples in the text. • A Script file is available on the Bb (file name: Ch4Queries.sql) • After completing all examples, do the HW (hint: see the tables below for the final schema and the sample output on the Bb under “Assignments” store_reps pk rep_id NUMBER(5) pk last VARCHAR2(15) first VARCHAR2(10) cpk, fk name VARCHAR2(30) rep_contracts store_id NUMBER(8) Dr. Chen, Oracle Database System (Oracle) name VARCHAR2(5) base_salary NUMBER(7,2) fk book_stores store_id NUMBER(8) comm CHAR(1) contact VARCHAR2(30) cpk quarter CHAR(3) rep_id NUMBER(5) cpk, fk rep_id NUMBER(5) 41 Homework - Hands-On Assignments Upload the SQL and spooled files (*.sql and *.txt) to the Bb (under “Assignments & Projects”) by the deadline Read and Practice all examples on Chapters 4 • 1. Run the script files (in the folder \oradata\chapter4\): JLDB_Build_4.sql • 2. Read Oracle assignment and create a script file Oracle_ch4_Lname_Fname.sql for questions (#1 to #8; p.133) 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 UPLOAD both *.sql and spooled file Oracle_ch4_Spool_Lname_Fname.txt to Bb by the midnight before the next class. • Turn in a hardcopy of spooled file (*.txt ONLY) to me in the class. [correction on p.138: Name Datatype should be VARCHAR2(5)] Dr. Chen, Oracle Database System (Oracle) 42 How to Spool your Script and Output Files After you tested the script file of Oracle_ch4_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\chapter4\JLDB_Build_4.sql • 1. type the following on SQL> – Spool c:\oradata\Oracle_ch4_Spool_Lname_Fname.txt (make sure your name is entered) • 2. open Oracle_ch4_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) Upload the SQL and spooled files (*.sql and *.txt) to the Bb (under “Assignments & Projects”) by the deadline Dr. Chen, Oracle Database System (Oracle) 43 • End of chapter 4 Dr. Chen, Oracle Database System (Oracle) 44