Introduction to Oracle9i: SQL1 Basic SQL SELECT Statements

Introduction to Oracle9i: SQL2 Chapter Objectives Distinguish between an RDBMS and an ORDBMS Identify keywords, mandatory clauses, and optional clauses in a SELECT statement Select and view all columns of a table Select and view one column of a table

Introduction to Oracle9i: SQL3 Chapter Objectives Display multiple columns of a table Use a column alias to clarify the contents of a particular column Perform basic arithmetic operations in the SELECT clause

Introduction to Oracle9i: SQL4 Chapter Objectives Remove duplicate lists, using either the DISTINCT or UNIQUE keyword Combine fields, literals, and other data Format output

Introduction to Oracle9i: SQL5 Relational Database Management System (RDBMS) An RDBMS is the software program used to create the database and it allows you to enter, manipulate, and retrieve data

Introduction to Oracle9i: SQL6 Object Relational Database Management System (ORDBMS) Same as an RDBMS except it can be used to reference objects such as maps and object fields

Introduction to Oracle9i: SQL7 SELECT Statement Syntax SELECT statements are used to retrieve data from the database Syntax gives the basic structure, or rules, for a command

Introduction to Oracle9i: SQL8 SELECT Statement Syntax Optional clauses and keywords are shown in brackets

Introduction to Oracle9i: SQL9 SELECT Statement Syntax SELECT and FROM clauses are required SELECT clause identifies column(s) FROM clause identifies table(s) Each clause begins with a keyword

Introduction to Oracle9i: SQL10 Selecting All Data in a Table Substitute an asterisk for the column names in a SELECT clause

Introduction to Oracle9i: SQL11 Selecting One Column from a Table Enter column name in SELECT clause

Introduction to Oracle9i: SQL12 Selecting Multiple Columns from a Table Separate column names with a comma

Introduction to Oracle9i: SQL13 Operations Within the SELECT Statement Column alias can be used for column headings Perform arithmetic operations Suppress duplicates Concatenate data

Introduction to Oracle9i: SQL14 Column Alias List after column heading AS keyword is optional Enclose in double quotation marks: –If it contains blank space(s) –If it contains special symbol(s) –To retain case

Introduction to Oracle9i: SQL15 Column Alias Example

Introduction to Oracle9i: SQL16 Arithmetic Operations Executed left to right Multiplication and division are solved first Addition and subtraction are solved last Override order with parentheses

Introduction to Oracle9i: SQL17 Example Arithmetic Operation with Column Alias

Introduction to Oracle9i: SQL18 Suppressing Duplicates Enter DISTINCT or UNIQUE after SELECT keyword

Introduction to Oracle9i: SQL19 Concatenation Can combine data with string literal Use concatenation operator, || Allows use of column alias

Introduction to Oracle9i: SQL20 Concatenation Example

Introduction to Oracle9i: SQL21 Purpose of Joins Joins are used to link tables and reconstruct data in a relational database Joins can be created through: –Conditions in a WHERE clause –Use of JOIN keywords in FROM clause

Introduction to Oracle9i: SQL22 Cartesian Join Created by omitting joining condition in the WHERE clause or through CROSS JOIN keywords in the FROM clause Results in every possible row combination (m * n)

Introduction to Oracle9i: SQL23 Cartesian Join Example: Omitted Condition

Introduction to Oracle9i: SQL24 Cartesian Join Example: CROSS JOIN Keywords

Introduction to Oracle9i: SQL25 Equality Join Links rows through equivalent data that exists in both tables Created by: –Creating equivalency condition in the WHERE clause –Using NATURAL JOIN, JOIN…USING, or JOIN…ON keywords in the FROM clause

Introduction to Oracle9i: SQL26 Equality Join: WHERE Clause Example

Introduction to Oracle9i: SQL27 Equality Join: NATURAL JOIN Syntax: tablename NATURAL JOIN tablename

Introduction to Oracle9i: SQL28 Equality Join: JOIN…USING Syntax: tablename JOIN tablename USING (columnname)

Introduction to Oracle9i: SQL29 Equality Join: JOIN…ON Syntax: tablename JOIN tablename ON condition

Introduction to Oracle9i: SQL30 JOIN Keyword Overview Use NATURAL JOIN when tables have one column in common Use JOIN…USING when tables have more than one column in common Use JOIN…ON when a condition is needed to specify a relationship other than equivalency Using JOIN keyword frees the WHERE clause for exclusive use in restricting rows

Introduction to Oracle9i: SQL31 Non-Equality Joins In WHERE clause, use any comparison operator other than equal sign In FROM clause, use JOIN…ON keywords with non-equivalent condition

Introduction to Oracle9i: SQL32 Non-Equality Join: WHERE Clause Example

Introduction to Oracle9i: SQL33 Non-Equality Join: JOIN…ON Example

Introduction to Oracle9i: SQL34 Self-Joins Used to link a table to itself Requires use of column qualifier

Introduction to Oracle9i: SQL35 Self-Join: WHERE Clause Example

Introduction to Oracle9i: SQL36 Self-Join: JOIN…ON Example

Introduction to Oracle9i: SQL37 Outer Joins // Use to include rows that do not have a match in the other table In WHERE clause, include outer join operator (+) next to table with missing rows to add NULL rows In FROM clause, use FULL, LEFT, or RIGHT with OUTER JOIN keywords

Introduction to Oracle9i: SQL38 Outer Join: WHERE Clause Example

Introduction to Oracle9i: SQL39 Outer Join: OUTER JOIN Keyword Example

Introduction to Oracle9i: SQL40 Set Operators XX Used to combine the results of two or more SELECT statements

Introduction to Oracle9i: SQL41 Set Operator Example

Introduction to Oracle9i: SQL42 Joining Three or More Tables Same procedure as joining two tables Will always results in one less join than the number of tables being joined

Introduction to Oracle9i: SQL43 Joining Three or More Tables: Example