Chapter 3: SQL – Part I Yong Choi School of Business CSU, Bakersfield

2 Study Objectives Understand the basic commands and functions of SQL Learn how SQL is used for data manipulation (to add, modify, delete, and retrieve data) Learn how to use SQL to query a database to extract useful information Learn how SQL is used for data administration (to create tables, indexes, and views) Practice SQL

3 Ideal Database Language Requirements Create database and table structures. –SQL has a data definition component that gives us the ability to meet this requirement. Manage the data component of the database. –SQL gives us a set of commands to add, update, and delete data within the database tables. Provide detailed data query capability. –"Standard" SQL uses a set of approximately thirty commands that allow us to retrieve data and to convert the raw data into useful information.

4 Introduction to SQL Standard Query Language (SQL) is the relational model’s standard language. The original version of SQL was developed at IBM's San Jose Research Laboratory. This language, originally called Sequel. The Sequel language has evolved since then, and its name has changed to SQL (Structured Query Language). In 1986, the American National Standards Institute (ANSI) published an SQL standard. –In 1992, work was completed on a significantly revised version of the SQL standard (SQL-92).

5 Introduction to SQL (con’t) SQL is relatively easy to learn –SQL commands set has a basic vocabulary of less than 100 words. SQL is a nonprocedural language. So, it is much easier to use. –Its user merely commands what is to be done without having to worry about how it's to be done. –Procedural language: COBOL, C, or Pascal.

6 More about SQL Three basic data functions by SQL, and their basic SQL commands: 1.Data definition through the use of CREATE 2.Data manipulation through INSERT, UPDATE, and DELETE 3.Data querying through the use of SELECT AND MANY OTHERS, which is the basis for all SQL queries. –We will try this first since we just completed all Access queries.

7 Basic Structure of SQL Queries SQL relation is not a set of tuples because a set does not allow two identical members; rather it is a multi-set (a bag) of tuples. A SQL query has the form: SELECT FROM [WHERE ] [GROUP BY ] [HAVING ] [ORDER BY ]

8 The SELECT and FROM Statement The SELECT statement is used to select data from a table. The tabular result is stored in a result table (called the result set). The FROM statement is used to select tables. Syntax: –SELECT column_name(s) –FROM table_name To select all columns from a table, use a * symbol instead of column names: –SELECT * FROM table_name

9 The WHERE Statement To conditionally select data from a table, a WHERE clause can be added to the SELECT statement. Syntax: –SELECT column –FROM table –WHERE column operator value

10 Typical Data Types INTEGER –Numbers without a decimal point SMALLINT –Uses less space than INTEGER DECIMAL(p,q) –P number of digits; q number of decimal places CHAR(n) –Character string n places long DATE –Dates in DD-MON-YYYY or MM/DD/YYYY

11 Semicolon after SQL Statements? Semicolon is the standard way to separate each SQL statement in database systems that allow more than one SQL statement to be executed in the same call to the server. MS Access and SQL Server 2000 do not require to put a semicolon after each SQL statement, but other database SQLs force you to use it such as Oracle. So, you must use a semicolon for this class. Oracle –Access SQL commands are not case sensitive (including table and attribute names) but try to follow exact names for better readability. –Download SQL data file form the class web site.

12 CustomerNumCustomerNameStreetCityStateZipBalanceCreditLimitRepNum 148Al's Appliance and Sport 2837 Greenway FillmoreFL33336$6,550$7,50020 OrderNumPartNumNumOrderedQuotedPrice 21608AT9411$21.95 OrderNumOrderDateCustomerNum /20/ Customer OrderLine Orders PartNumDescriptionOnHandClassWarehousePrice AT94Iron50HW3$24.95 Part Rep RepNumLastNameFirstNameStreetCityStateZipCommissionRate 20KaiserValerie624 RandallGroveFL33321$20,

13 SQL Examples Example 2: Save as example 2 –List the number, name, and balance of all customers. Example 3: Save as example 3 –List the complete Part table.

14 Oracle 7.0 SQL Example SQL> select * from employee; EMP_ID EMP_LNAME EMP_FNAME EMP_SALARY EMP_DEPT_NO Kim John Johnson Steve Jonson Paul Lee Jim Basinger Jon Stone Sharon rows selected.

15 SQL Examples – WHERE clause Example 4: Save as example 4 –List the name of every customers with $10,000 credit limit. Example 5: Save as example 5 –Find the name of customer 148.

16 SQL Comparison Operators FOR WHERE clause AND / OR logical operators NOT Warehouse =‘3’ LIKE: LIKE ‘a*’, LIKE ‘*s’, Like ‘*Oxford*’ (NOT) BETWEEN AND (NOT) IN (123, 345)

17 SQL Examples Example 6: Save as example 6 –Find the customer name for every customer located in the city of Grove Example 7: Save as example 7 –List the number, name, credit limit, and balance for customers with credit limits that exceed their balances.

18 SQL Examples – Compound Conditions Example 8: Save as example 8 –List the description of all parts that are located in warehouse 3 and for which there are more than 20 units on hand. Example 9: Save as example 9 –List the descriptions of all parts that are located in warehouse 3 or for which there are more than 20 units on hand.

19 SQL Examples Example 10: Save as example 10 –List the description of all parts that are not in warehouse 3. Example 11: Save as example 11 –List the number, name, and balance of all customers with balances greater that or equal to $1,000 and less than or equal to $5,000.

20 SQL Examples – Computed Field Computed field can involve: –addition(+), subtraction(-), Multiplication(*), or division (/) Example 12: Save as example 12 –List the number, name and available credit for all customers. Example 13: Save as example 13 –List the number, name, and available credit for all customers with credit limits that exceed their balances.

21 SQL Examples – LIKE and IN Example 14: Save as example 14 –List the number, name, and complete address of every customer located on a street that contain the letters “Oxford.” – like *oxford* Customer name start with “A” – like a* Customer address end with letter “d” – like *d Example 15: Save as example 15 –List the number, name, and credit limit for every customer with a credit of $7,500, $10,000, or $15,000. Use “in” operator

22 SQL Examples Default value of ORDER BY: ascending Example 16: Save as example 16 –List the number, name, and credit limit of all customers. Sort the customers by name in ascending order. Example 17: Save as example 17 –List the number, name, and credit limit of all customers. Sort the customers by name in ascending order within credit limit in descending order.