Basic SQL SELECT Statements
description
Transcript of Basic SQL SELECT Statements
![Page 1: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/1.jpg)
Introduction to Oracle9i: SQL 1
Basic SQL SELECT Statements
![Page 2: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/2.jpg)
Introduction to Oracle9i: SQL 2
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
![Page 3: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/3.jpg)
Introduction to Oracle9i: SQL 3
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
![Page 4: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/4.jpg)
Introduction to Oracle9i: SQL 4
Chapter Objectives
• Remove duplicate lists, using either the DISTINCT or UNIQUE keyword
• Combine fields, literals, and other data• Format output
![Page 5: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/5.jpg)
Introduction to Oracle9i: SQL 5
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
![Page 6: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/6.jpg)
Introduction to Oracle9i: SQL 6
Object Relational Database Management System (ORDBMS)
Same as an RDBMS except it can be used to reference objects such as maps and object fields
![Page 7: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/7.jpg)
Introduction to Oracle9i: SQL 7
SELECT Statement Syntax
• SELECT statements are used to retrieve data from the database
• Syntax gives the basic structure, or rules, for a command
![Page 8: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/8.jpg)
Introduction to Oracle9i: SQL 8
SELECT Statement Syntax
Optional clauses and keywords are shown in brackets
![Page 9: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/9.jpg)
Introduction to Oracle9i: SQL 9
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
![Page 10: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/10.jpg)
Introduction to Oracle9i: SQL 10
Selecting All Data in a Table
Substitute an asterisk for the column names in a SELECT clause
![Page 11: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/11.jpg)
Introduction to Oracle9i: SQL 11
Selecting One Column from a Table
Enter column name in SELECT clause
![Page 12: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/12.jpg)
Introduction to Oracle9i: SQL 12
Selecting Multiple Columns from a Table
Separate column names with a comma
![Page 13: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/13.jpg)
Introduction to Oracle9i: SQL 13
Operations Within the SELECT Statement
• Column alias can be used for column headings
• Perform arithmetic operations• Suppress duplicates• Concatenate data
![Page 14: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/14.jpg)
Introduction to Oracle9i: SQL 14
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
![Page 15: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/15.jpg)
Introduction to Oracle9i: SQL 15
Column Alias Example
![Page 16: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/16.jpg)
Introduction to Oracle9i: SQL 16
Arithmetic Operations
• Executed left to right• Multiplication and division are solved first• Addition and subtraction are solved last• Override order with parentheses
![Page 17: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/17.jpg)
Introduction to Oracle9i: SQL 17
Example Arithmetic Operation with Column Alias
![Page 18: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/18.jpg)
Introduction to Oracle9i: SQL 18
Suppressing Duplicates
Enter DISTINCT or UNIQUE after SELECT keyword
![Page 19: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/19.jpg)
Introduction to Oracle9i: SQL 19
Concatenation
• Can combine data with string literal • Use concatenation operator, ||• Allows use of column alias
![Page 20: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/20.jpg)
Introduction to Oracle9i: SQL 20
Concatenation Example
![Page 21: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/21.jpg)
Introduction to Oracle9i: SQL 21
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
![Page 22: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/22.jpg)
Introduction to Oracle9i: SQL 22
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)
![Page 23: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/23.jpg)
Introduction to Oracle9i: SQL 23
Cartesian Join Example:Omitted Condition
![Page 24: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/24.jpg)
Introduction to Oracle9i: SQL 24
Cartesian Join Example:CROSS JOIN Keywords
![Page 25: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/25.jpg)
Introduction to Oracle9i: SQL 25
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
![Page 26: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/26.jpg)
Introduction to Oracle9i: SQL 26
Equality Join: WHERE Clause Example
![Page 27: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/27.jpg)
Introduction to Oracle9i: SQL 27
Equality Join: NATURAL JOIN
Syntax: tablename NATURAL JOIN tablename
![Page 28: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/28.jpg)
Introduction to Oracle9i: SQL 28
Equality Join: JOIN…USING
Syntax: tablename JOIN tablename USING (columnname)
![Page 29: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/29.jpg)
Introduction to Oracle9i: SQL 29
Equality Join: JOIN…ON
Syntax: tablename JOIN tablename ON condition
![Page 30: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/30.jpg)
Introduction to Oracle9i: SQL 30
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
![Page 31: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/31.jpg)
Introduction to Oracle9i: SQL 31
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
![Page 32: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/32.jpg)
Introduction to Oracle9i: SQL 32
Non-Equality Join: WHERE Clause Example
![Page 33: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/33.jpg)
Introduction to Oracle9i: SQL 33
Non-Equality Join: JOIN…ON Example
![Page 34: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/34.jpg)
Introduction to Oracle9i: SQL 34
Self-Joins
• Used to link a table to itself• Requires use of column qualifier
![Page 35: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/35.jpg)
Introduction to Oracle9i: SQL 35
Self-Join: WHERE Clause Example
![Page 36: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/36.jpg)
Introduction to Oracle9i: SQL 36
Self-Join: JOIN…ON Example
![Page 37: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/37.jpg)
Introduction to Oracle9i: SQL 37
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
![Page 38: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/38.jpg)
Introduction to Oracle9i: SQL 38
Outer Join: WHERE Clause Example
![Page 39: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/39.jpg)
Introduction to Oracle9i: SQL 39
Outer Join: OUTER JOIN Keyword Example
![Page 40: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/40.jpg)
Introduction to Oracle9i: SQL 40
Set Operators XX
Used to combine the results of two or more SELECT statements
![Page 41: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/41.jpg)
Introduction to Oracle9i: SQL 41
Set Operator Example
![Page 42: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/42.jpg)
Introduction to Oracle9i: SQL 42
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
![Page 43: Basic SQL SELECT Statements](https://reader036.fdocuments.net/reader036/viewer/2022062411/56816793550346895ddccc82/html5/thumbnails/43.jpg)
Introduction to Oracle9i: SQL 43
Joining Three or More Tables: Example