7 1 Chapter 7 Introduction to Structured Query Language (SQL) Database Systems: Design, Implementation, and Management, Seventh Edition, Rob and Coronel

7 2 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel In this chapter, you will learn: The basic commands and functions of SQL How to use SQL for data administration (to create tables, indexes, and views) How to use SQL for data manipulation (to add, modify, delete, and retrieve data) How to use SQL to query a database to extract useful information

7 3 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Introduction to SQL SQL functions fit into two broad categories: –Data definition language SQL includes commands to: –Create database objects, such as tables, indexes, and views –Define access rights to those database objects –Data manipulation language Includes commands to insert, update, delete, and retrieve data within database tables

7 4 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Introduction to SQL (continued) SQL is relatively easy to learn Basic command set has vocabulary of less than 100 words Nonprocedural language American National Standards Institute (ANSI) prescribes a standard SQL Several SQL dialects exist

7 5 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Introduction to SQL (continued)

7 6 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Introduction to SQL (continued)

7 7 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Introduction to SQL (continued)

7 8 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Data Definition Commands Examine simple database model and database tables that will form basis for many SQL examples Understand data environment

7 9 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel The Database Model

7 10 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel The Database Model (continued)

7 11 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Creating the Database Following two tasks must be completed: –Create database structure –Create tables that will hold end-user data First task: –RDBMS creates physical files that will hold database –Tends to differ substantially from one RDBMS to another

7 12 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel The Database Schema Authentication –Process through which DBMS verifies that only registered users are able to access database –Log on to RDBMS using user ID and password created by database administrator Schema –Group of database objects—such as tables and indexes—that are related to each other

7 13 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Data Types Data type selection is usually dictated by nature of data and by intended use Pay close attention to expected use of attributes for sorting and data retrieval purposes

7 14 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Data Types (continued)

7 15 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Creating Table Structures Use one line per column (attribute) definition Use spaces to line up attribute characteristics and constraints Sql commands are capitalized NOT NULL specification UNIQUE specification

7 16 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Creating Table Structures (continued) Primary key attributes indicate both a NOT NULL and a UNIQUE specification RDBMS will automatically enforce referential integrity for foreign keys Command sequence ends with semicolon

7 17 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel SQL Constraints NOT NULL constraint –Ensures that column does not accept nulls UNIQUE constraint –Ensures that all values in column are unique DEFAULT constraint –Assigns value to attribute when a new row is added to table CHECK constraint –Validates data when attribute value is entered

7 18 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Creating Table Structures (continued) CREATE TABLE CUSTOMER( CUS_CODE NUMBER(7) PRIMARY KEY, CUS_LNAME VARCHAR2 (20), CUS_ZIP CHAR (5), AGENT_CODE NUMBER (3) DEFAULT 412);

7 19 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Creating Table Structures (continued) CREATE TABLE AGENT( AGENT_CODE NUMBER(3) PRIMARY KEY, AGENT_PHONE CHAR (10));

7 20 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Creating Table Structures (continued) CREATE TABLE Product( p_code CHAR(10), /*...*/ p_descript VARCHAR2(35), p_indate DATE, p_onhand SMALLINT, p_min SMALLINT, p_price NUMBER(8,2) NOT NULL, p_discount NUMBER(4,2), v_code INTEGER CONSTRAINT v_code_fk REFERENCES Vendor(v_code), CONSTRAINT p_code_pk PRIMARY KEY (p_code));

7 21 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Creating Table Structures (continued) CREATE TABLE Product( p_code CHAR(10) CONSTRAINT p_code_pk PRIMARY KEY, p_descript VARCHAR2(35), p_indate DATE, p_onhand SMALLINT, p_min SMALLINT, p_price NUMBER(8,2) NOT NULL, p_discount NUMBER(4,2), v_code INTEGER CONSTRAINT v_code_fk REFERENCES Vendor(v_code));

7 22 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Creating Table Structures (continued) CREATE TABLE Employee( ssn CHAR(10), salary NUMBER(9,2), title VARCHAR2(20), class NUMBER(1) constraint class_ck CHECK (class BETWEEN 1 AND 4), CONSTRAINT title_uk UNIQUE (title), CONSTRAINT ssn_salary_pk PRIMARY KEY (ssn, salary));

7 23 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel SQL Indexes When primary key is declared, DBMS automatically creates unique index Often need additional indexes Using CREATE INDEX command, SQL indexes can be created on basis of any selected attribute Composite index –Index based on two or more attributes –Often used to prevent data duplication

7 24 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel SQL Indexes (continued) CREATE [UNIQUE] INDEX indexname ON tablename (column1 [, column2]) CREATE INDEX Emptest on Test (emp_num)

7 25 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel SQL Indexes (continued)

7 26 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Data Manipulation Commands Adding table rows Saving table changes Listing table rows Updating table rows Restoring table contents Deleting table rows Inserting table rows with a select subquery

7 27 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Adding Table Rows INSERT –Used to enter data into table –Insert a row each time –Syntax: INSERT INTO tablename VALUES (value1, value2, …, valuen);

7 28 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Adding Table Rows (continued) When entering values, notice that: –Row contents are entered between parentheses –Character and date values are entered between apostrophes –Numerical entries are not enclosed in apostrophes –Attribute entries are separated by commas –A value is required for each column Use NULL for unknown values

7 29 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Adding Table Rows (continued) INSERT INTO Product VALUES (‘BRT-345’, ‘Titanium drill bit’, TO_DATE(’18-Oct-05’, ’DD-MON-YY’), 75, 10, 4.5, 0.06, NULL); or TO_DATE (’18/Oct/05’, ’DD/MON/YY’) or TO_DATE(’10/18/2005’, ‘MM/DD/YYYY’) or TO_DATE(‘October 18, 2005’, ‘Month DD, YYYY’)

7 30 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Saving Table Changes Changes made to table contents are not physically saved on disk until, one of the following occurs: –Database is closed –Program is closed –COMMIT command is used Syntax: –COMMIT [WORK]; Will permanently save any changes made to any table in the database

7 31 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Listing Table Rows SELECT –Used to list contents of table –Syntax: SELECT columnlist FROM tablename; Columnlist represents one or more attributes, separated by commas Asterisk can be used as wildcard character to list all attributes

7 32 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Listing Table Rows (continued) SELECT p_code, p_descript, p_indate, p_qoh, p_min, p_price, p_discount, v_code FROM Product; SELECT * FROM Product;

7 33 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Listing Table Rows (continued)

7 34 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Updating Table Rows UPDATE –Modify data in a table –Syntax: UPDATE tablename SET columnname = expression [, columname = expression] [WHERE conditionlist]; If more than one attribute is to be updated in row, separate corrections with commas

7 35 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Updating Table Rows (continued) UPDATE Product SET p_indate = ’18-Jan-2006’, p_price = 7.6 WHERE p_code = ‘13-Q2/P2’;

7 36 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Restoring Table Contents ROLLBACK –Used to restore database to its previous condition –Only applicable if COMMIT command has not been used to permanently store changes in database Syntax: –ROLLBACK; COMMIT and ROLLBACK only work with data manipulation commands that are used to add, modify, or delete table rows

7 37 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Deleting Table Rows DELETE –Deletes a table row –Syntax: DELETE FROM tablename [WHERE conditionlist ]; WHERE condition is optional If WHERE condition is not specified, all rows from specified table will be deleted

7 38 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Deleting Table Rows (continued) DELETE FROM Product WHERE p_code = ‘BRT-345’;

7 39 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Inserting Table Rows with a Select Subquery INSERT –Inserts multiple rows from another table (source) –Uses SELECT subquery Query that is embedded (or nested) inside another query Executed first –Syntax: INSERT INTO tablename SELECT columnlist FROM tablename;

7 40 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Inserting Table Rows with a Select Subquery (continued) INSERT INTO p SELECT * from Product; Employee(name, address, emp_num, salary) Emp1(addr, sal, empno) INSERT INTO Emp1 SELECT address, salary, emp_num FROM Employee;

7 41 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Inserting Table Rows with a Select Subquery (continued) INSERT INTO Emp1 SELECT address, emp_num, salary FROM Employee; (The order of attributes matter in the above) INSERT INTO Emp1 SELECT * FROM Employee; (The number of attributes are not the same!)

7 42 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions Select partial table contents by placing restrictions on rows to be included in output –Add conditional restrictions to SELECT statement, using WHERE clause Syntax: –SELECT columnlist FROM tablelist [ WHERE conditionlist ] ;

7 43 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued) SELECT p_descript, p_indate, p_price, v_code FROM Product WHERE v_code = 21344;

7 44 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued)

7 45 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued)

7 46 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued)

7 47 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued) SELECT p_descript, p_indate, p_price, v_code FROM Product WHERE v_code <>21344;

7 48 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued)

7 49 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued) SELECT p_descript, p_qoh, p_min, p_price FROM Product WHERE p_price <= 10;

7 50 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued)

7 51 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued) SELECT p_code, p_descript, p_qoh, p_min, p_price FROM Product WHERE p_code <= ‘1558-QW1’;

7 52 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued)

7 53 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued) SELECT p_descript, p_qoh, p_min, p_price, p_indate FROM Product WHERE p_indate >= ’20-Jan-2006’;

7 54 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued)

7 55 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued) SELECT p_descript, p_qoh, p_price, p_qoh*p_price FROM Product;

7 56 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued)

7 57 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued) SELECT p_descript, p_qoh, p_price, p_qoh*p_price AS totalvalue FROM Product;

7 58 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Selecting Rows with Conditional Restrictions (continued)

7 59 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Arithmetic Operators: The Rule of Precedence Perform operations within parentheses Perform power operations Perform multiplications and divisions Perform additions and subtractions

7 60 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Arithmetic Operators: The Rule of Precedence (continued)

7 61 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Logical Operators: AND, OR, and NOT SELECT p_descript, p_indate, p_price, v_code FROM Product WHERE v_code = OR v_code = 24288;

7 62 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Logical Operators: AND, OR, and NOT (continued)

7 63 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Logical Operators: AND, OR, and NOT (continued) SELECT p_descript, p_indate, p_price, v_code FROM Product WHERE p_price ’15-Jan- 2006’;

7 64 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Logical Operators: AND, OR, and NOT (continued)

7 65 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Logical Operators: AND, OR, and NOT (continued) SELECT p_descript, p_indate, p_price, v_code FROM product WHERE (p_price ’15-Jan- 2006’) OR v_code = 24288;

7 66 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Logical Operators: AND, OR, and NOT (continued)

7 67 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Special Operators BETWEEN –Used to check whether attribute value is within a range IS NULL –Used to check whether attribute value is null LIKE –Used to check whether attribute value matches given string pattern

7 68 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Special Operators (continued) IN –Used to check whether attribute value matches any value within a value list EXISTS –Used to check if subquery returns any rows

7 69 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Special Operators (continued) SELECT * FROM Product WHERE p_price BETWEEN AND ; SELECT * FROM product WHERE p_price > AND p_price<100.00; SELECT p_code, p_descript, v_code FROM Product WHERE v_code IS NULL;

7 70 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Special Operators (continued) The LIKE special operator is used in conjunction with wildcards to find patterns within string attributes. –% means any and all following characters are eligible. For example, ‘J%’ includes Johnson, Jones, July, etc. ‘Jo%’ includes Johnson, Jones, etc. –_ means any one character may be substituted for the underscore. For example, ‘_o_es’ includes Jones, Cones, Cokes, totes, ets.

7 71 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Special Operators (continued) SELECT v_name, v_contact, v_areacode FROM Vendor WHERE v_contact LIKE ‘Smith%’; SELECT v_name, v_contact, v_areacode FROM Vendor WHERE UPPER(v_contact) LIKE ‘SMITH%’; SELECT v_name, v_contact, v_areacode FROM Vendor WHERE v_contact NOT LIKE ‘Smith%’;

7 72 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Special Operators (continued) SELECT * FROM Product WHERE v_code IN (21344, 24288); SELECT v_code, v_name FROM Vendor WHERE v_code IN (SELECT v_code FROM Product); SELECT * FROM Vendor WHERE v_code EXIST (SELECT * FROM Product WHERE p_qoh <= p_min);

7 73 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Advanced Data Definition Commands All changes in table structure are made by using ALTER command –Followed by keyword that produces specific change –Following three options are available: ADD MODIFY DROP

7 74 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Changing a Column’s Data Type ALTER can be used to change data type Some RDBMSs (such as Oracle) do not permit changes to data types unless column to be changed is empty

7 75 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Changing a Column’s Data Characteristics Use ALTER to change data characteristics If column to be changed already contains data, changes in column’s characteristics are permitted if those changes do not alter the data type

7 76 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Adding a Column Use ALTER to add/modify column ALTER TABLE Customer ADD address VARCHAR2(20); ALTER TABLE Customer MODIFY balance NUMBER(8,2);

7 77 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Dropping a Column Use ALTER to drop column –Some RDBMSs impose restrictions on the deletion of an attribute ALTER TABLE Product DROP CONSTRAINT v_code_fk;

7 78 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Dropping a Column (continued) UPDATE Product SET p_salecode = ‘2’ WHERE p_code = ‘1546-QQ2’; UPDATE Product SET p_salecode = ‘2’ WHERE p_code = ‘1546-QQ2’ OR p_code = ‘2232/QTY’; UPDATE Product SET p_salecode = ‘2’ WHERE p_indate < ’25-Dec-2005’;

7 79 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Advanced Data Updates

7 80 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Copying Parts of Tables SQL permits copying contents of selected table columns so that the data need not be reentered manually into newly created table(s) First create the PART table structure Next add rows to new PART table using PRODUCT table rows

7 81 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Copying Parts of Tables (continued) CREATE TABLE Part AS SELECT p_code AS part_code, p_descript AS part_descript, p_price AS part_price, v_code FROM Product;

7 82 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Copying Parts of Tables (continued)

7 83 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Adding Primary and Foreign Key Designations When table is copied, integrity rules do not copy, so primary and foreign keys need to be manually defined on new table User ALTER TABLE command –Syntax: ALTER TABLE tablename ADD PRIMARY KEY(fieldname); For foreign key, use FOREIGN KEY in place of PRIMARY KEY

7 84 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Deleting a Table from the Database DROP –Deletes table from database –Syntax: DROP TABLE tablename;

7 85 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Advanced Select Queries SQL provides useful functions that can: –Count –Find minimum and maximum values –Calculate averages SQL allows user to limit queries to only those entries having no duplicates or entries whose duplicates may be grouped

7 86 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Ordering a Listing (continued) SELECT p_code, p_descript, p_indate, p_price FROM Product ORDER BY p_price; SELECT p_code, p_descript, p_indate, p_price FROM Product ORDER BY p_price DESC; SELECT emp_lname, emp_fname, emp_initial, emp_areacode, emp_phone FROM Employee ORDER BY emp_lname, emp_fname, emp_initial;

7 87 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Ordering a Listing

7 88 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Ordering a Listing (continued)

7 89 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Ordering a Listing (continued) SELECT p_descript, v_code, p_indate, p_price FROM Product WHERE p_indate < ’21-Jan-2006’ AND p_price <= ORDER BY v_code, p_price DESC;

7 90 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Ordering a Listing (continued)

7 91 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Listing Unique Values (continued) SELECT DISTINCT v_code FROM Product;

7 92 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Listing Unique Values

7 93 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Aggregate Functions

7 94 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Aggregate Functions (continued)

7 95 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Aggregate Functions (continued)

7 96 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Aggregate Functions (continued)

7 97 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Aggregate Functions (continued)

7 98 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Grouping Data

7 99 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Grouping Data (continued)

7 100 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Grouping Data (continued)

7 101 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Virtual Tables: Creating a View View is virtual table based on SELECT query –Can contain columns, computed columns, aliases, and aggregate functions from one or more tables Base tables are tables on which view is based Create view by using CREATE VIEW command

7 102 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Virtual Tables: Creating a View (continued)

7 103 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Joining Database Tables Ability to combine (join) tables on common attributes is most important distinction between relational database and other databases Join is performed when data are retrieved from more than one table at a time Join is generally composed of an equality comparison between foreign key and primary key of related tables

7 104 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Joining Database Tables (continued)

7 105 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Joining Database Tables (continued) SLECT p_descript, p_price, v_name, v_contact, v_areacode, v_phone FROM Product, Vendor WHERE product.v_code = vendor.v_code;

7 106 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Joining Database Tables (continued)

7 107 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Joining Database Tables (continued) SLECT p_descript, p_price, v_name, v_contact, v_areacode, v_phone FROM Product, Vendor WHERE product.v_code = vendor.v_code AND p_indate > ’15-Jan-2006’;

7 108 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Joining Database Tables (continued)

7 109 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Joining Tables with an Alias Alias can be used to identify source table Any legal table name can be used as alias Add alias after table name in FROM clause –FROM tablename alias

7 110 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Recursive Joins

7 111 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Recursive Joins (continued) SELECT E.emp_mgr, E.emp_lname, M.emp_num, E.emp_lname FROM Emp E, Emp M WHERE E.emp_mgr = M.emp_num ORDER BY E.emp_mgr;

7 112 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Recursive Joins (continued)

7 113 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Outer Joins SELECT p_code, V.v_code, v_name FROM product P, vendor V WHERE V.v_code = P.v_code(+); SELECT p_code, V.v_code, v_name FROM product P, vendor V WHERE P.v_code = V.v_code(+);

7 114 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Left Outer Joins

7 115 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Right Outer Joins (continued)

7 116 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Grant and Revoke Privileges on Tables Security is an issue in the access of a table from a foreign account. The creator of the table has no restriction on access and may or may not pass along manipulation privileges to others. GRANT {priv | ALL} ON table-name TO {specific user | PUBLIC};

7 117 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Grant and Revoke Privileges on Tables GRANT SELECT, INSERT ON Customer TO fred, mary, joe; GRANT ALL GRANT SELECT ON Customer ON Customer TO fred; TO PUBLIC;

7 118 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Grant and Revoke Privileges on Tables SELECT * FROM mary.Customer; REVOKE SELECT ON Customer FROM PUBLIC;

7 119 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Exercises 1. Student(stno, sname) Grade_report(student_number, course_no,grade) (1) List the names of students who have earned A’s or B’s in any course? (2)List the names and grades of all students who have earned A’s or B’s in any course?

7 120 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Exercises Course(course_number, credit_hours, course_name, offering_dept) Department(dept_code, dept_name) Find the names of all departments that offer a course with “INTRO” in the title)

7 121 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Exercises Student(stno, sname, major, class) Grade_report(student_number, section_id, grade) Section(section_id, course_num, semester, year, instructor, bldg, room) List the student name, student major code, and section identifier of students who earned C’s in courses taught by Professor Johns (JOHNS)?

7 122 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Exercises Room(room_id, capacity) List all room have a below-average capacity?

7 123 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Exercises SAILORS(S_ID, S_NAME, S_RATING, S_AGE) BOATS(B_ID, B_NAME, B_COLOR) RESERVES(S_ID, B_ID, R_DAY) A.Find all sailors with a rating above 7. B.Find the name of sailors who have reserved a red or a green boat. C.Find the name of sailors who are older than the oldest sailors with a rating of 10.

7 124 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Nulls Revisited Name Salary Joe 1000 Sam 2000 Bill 3000 Dave SELECT count(*), avg(salary), sum(salary), max(salary), min(salary) FROM

7 125 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Nulls Revisited Name Salary Joe 1000 Sam 2000 Bill 3000 Dave SELECT count(*), avg(salary), sum(salary), max(salary), min(salary) FROM Sal;

7 126 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Nulls Revisited count(*) avg sum min max Select avg(NVL(salary, 0)) from Sal; AVG(NVL(SALARY, 0)) 1500

7 127 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Delete and Referential Constraint On Delete Restrict –Default referential integrity delete option, which is not explicitly allowed in Oracle. On Delete Cascade (dangerous!) Create table employee ( empno number (3) primary key, empname varchar2(20), dept number(3) references department(deptno) on delete cascade);

7 128 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Delete and Referential Constraint On Delete Set NULL Create table Employee ( empno number (3) primary key, empname varchar2(20), dept number(3) references Department(deptno) on delete set NULL);

7 129 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Summary SQL commands can be divided into two overall categories: –Data definition language commands –Data manipulation language commands The ANSI standard data types are supported by all RDBMS vendors in different ways Basic data definition commands allow you to create tables, indexes, and views

7 130 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Summary (continued) DML commands allow you to add, modify, and delete rows from tables The basic DML commands are SELECT, INSERT, UPDATE, DELETE, COMMIT, and ROLLBACK INSERT command is used to add new rows to tables SELECT statement is main data retrieval command in SQL

7 131 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Summary (continued) Many SQL constraints can be used with columns The column list represents one or more column names separated by commas WHERE clause can be used with SELECT, UPDATE, and DELETE statements to restrict rows affected by the DDL command

7 132 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Summary (continued) Aggregate functions –Special functions that perform arithmetic computations over a set of rows ORDER BY clause –Used to sort output of SELECT statement –Can sort by one or more columns and use either an ascending or descending order Join output of multiple tables with SELECT statement

7 133 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Summary (continued) Natural join uses join condition to match only rows with equal values in specified columns Right outer join and left outer join used to select rows that have no matching values in other related table