Copyright  Oracle Corporation, All rights reserved. Introduction

I-2 Copyright  Oracle Corporation, All rights reserved. Data Storage on Different Media Electronic spreadsheet Filing cabinet Database SALGRADE SALGRADE GRADE LOSAL HISAL SALGRADE SALGRADE GRADE LOSAL HISAL DEPT DEPTNO DNAME LOC ACCOUNTING NEW YORK 20 RESEARCH DALLAS 30 SALES CHICAGO 40 OPERATIONS BOSTON DEPT DEPTNO DNAME LOC ACCOUNTING NEW YORK 20 RESEARCH DALLAS 30 SALES CHICAGO 40 OPERATIONS BOSTON

I-3 Copyright  Oracle Corporation, All rights reserved. Relational Database Concept Dr. E. F. Codd proposed the relational model for database systems in It is the basis for the relational database management system (RDBMS). The relational model consists of the following: – Collection of objects or relations – Set of operators to act on the relations – Data integrity for accuracy and consistency Dr. E. F. Codd proposed the relational model for database systems in It is the basis for the relational database management system (RDBMS). The relational model consists of the following: – Collection of objects or relations – Set of operators to act on the relations – Data integrity for accuracy and consistency

I-4 Copyright  Oracle Corporation, All rights reserved. Relational Database Definition A relational database is a collection of relations or two-dimensional tables. Database DEPTNO DNAME LOC 10 ACCOUNTING NEW YORK 20 RESEARCH DALLAS 30 SALES CHICAGO 40 OPERATIONS BOSTON DEPTNO DNAME LOC 10 ACCOUNTING NEW YORK 20 RESEARCH DALLAS 30 SALES CHICAGO 40 OPERATIONS BOSTON Table Name: DEPT EMPNO ENAME JOB DEPTNO 7839 KING PRESIDENT BLAKE MANAGER CLARK MANAGER JONES MANAGER 20 EMPNO ENAME JOB DEPTNO 7839 KING PRESIDENT BLAKE MANAGER CLARK MANAGER JONES MANAGER 20 Table Name: EMP

I-5 Copyright  Oracle Corporation, All rights reserved. Data Models Model of system in client’s mind Entity model of client’s model Table model of entity model Tables on disk Server

I-6 Copyright  Oracle Corporation, All rights reserved. Create an entity relationship diagram from business specifications or narratives Scenario – “... Assign one or more employees to a department...” – “... Some departments do not yet have assigned employees...” Create an entity relationship diagram from business specifications or narratives Scenario – “... Assign one or more employees to a department...” – “... Some departments do not yet have assigned employees...” Entity Relationship Model EMPLOYEE #* number *name ojob title EMPLOYEE #* number *name ojob title DEPARTMENT #* number *name olocation DEPARTMENT #* number *name olocation assigned to composed of

I-7 Copyright  Oracle Corporation, All rights reserved. Entity Relationship Modeling Conventions Entity Soft box Singular, unique name Uppercase Synonym in parentheses Attribute Singular name Lowercase Mandatory marked with “*” Optional marked with “o” Unique Identifier (UID) Primary marked with “#” Secondary marked with “(#)” EMPLOYEE #* number *name ojob title EMPLOYEE #* number *name ojob title DEPARTMENT #* number *name olocation DEPARTMENT #* number *name olocation assigned to composed of

I-8 Copyright  Oracle Corporation, All rights reserved. Relational Database Terminology EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO KING PRESIDENT 17-NOV BLAKEMANAGER MAY CLARK MANAGER JUN JONES MANAGER APR MARTINSALESMAN SEP ALLEN SALESMAN FEB TURNER SALESMAN SEP JAMES CLERK DEC WARDSALESMAN FEB FORDANALYST DEC SMITH CLERK DEC SCOTTANALYST DEC ADAMS CLERK JAN MILLER CLERK JAN

I-9 Copyright  Oracle Corporation, All rights reserved. Relating Multiple Tables Each row of data in a table is uniquely identified by a primary key (PK). Table Name: EMP Table Name: DEPT Primary key You can logically relate data from multiple tables using foreign keys (FK). Foreign key EMPNO ENAME JOB DEPTNO 7839 KING PRESIDENT BLAKE MANAGER CLARK MANAGER JONES MANAGER 20 DEPTNO DNAME LOC 10 ACCOUNTING NEW YORK 20 RESEARCH DALLAS 30 SALES CHICAGO 40 OPERATIONS BOSTON

I-10 Copyright  Oracle Corporation, All rights reserved. Relational Database Properties A relational database Can be accessed and modified by executing structured query language (SQL) statements Contains a collection of tables with no physical pointers Uses a set of operators A relational database Can be accessed and modified by executing structured query language (SQL) statements Contains a collection of tables with no physical pointers Uses a set of operators

I-11 Copyright  Oracle Corporation, All rights reserved. Communicating with a RDBMS Using SQL Database SQL> SELECT loc 2 FROM dept; SQL> SELECT loc 2 FROM dept; SQL statement is entered Statement is sent to database LOC NEW YORK DALLAS CHICAGO BOSTON LOC NEW YORK DALLAS CHICAGO BOSTON Data is displayed

I-12 Copyright  Oracle Corporation, All rights reserved. SQL Statements SELECT INSERTUPDATEDELETECREATEALTERDROPRENAMETRUNCATECOMMITROLLBACKSAVEPOINTGRANTREVOKESELECT INSERTUPDATEDELETECREATEALTERDROPRENAMETRUNCATECOMMITROLLBACKSAVEPOINTGRANTREVOKE Data retrieval Data retrieval Data manipulation language (DML) Data definition language (DDL) Transaction control Data control language (DCL)

I-13 Copyright  Oracle Corporation, All rights reserved. What Is PL/SQL? PL/SQL is an extension to SQL with design features of programming languages. Data manipulation and query statements of SQL are included within procedural units of code. PL/SQL is an extension to SQL with design features of programming languages. Data manipulation and query statements of SQL are included within procedural units of code.

I-14 Copyright  Oracle Corporation, All rights reserved. PL/SQL Environment PL/SQL block PL/SQL engine Oracle10g Server Procedural Statement Executor PL/SQL SQL SQL Statement Executor PL/SQL block

I-15 Copyright  Oracle Corporation, All rights reserved. Benefits of PL/SQL It is portable. You can declare identifiers. You can program with procedural language control structures. It can handle errors. It is portable. You can declare identifiers. You can program with procedural language control structures. It can handle errors.

I-16 Copyright  Oracle Corporation, All rights reserved. SQL and SQL*Plus Interaction SQL*Plus Buffer SQL scripts Server SQL Statements Query Results

I-17 Copyright  Oracle Corporation, All rights reserved. SQL Statements Versus SQL*Plus Commands SQLstatements SQL A languageA language ANSI standardANSI standard Keyword cannot be abbreviatedKeyword cannot be abbreviated Statements manipulate data and table definitions in the databaseStatements manipulate data and table definitions in the databaseSQL*Plus An environmentAn environment Oracle proprietaryOracle proprietary Keywords can be abbreviatedKeywords can be abbreviated Commands do not allow manipulation of values in the databaseCommands do not allow manipulation of values in the database SQLbufferSQL*PluscommandsSQL*Plusbuffer

I-18 Copyright  Oracle Corporation, All rights reserved. Log in to SQL*Plus. Describe the table structure. Edit your SQL statement. Execute SQL from SQL*Plus. Save SQL statements to files and append SQL statements to files. Execute saved files. Load commands from file to buffer to edit. Log in to SQL*Plus. Describe the table structure. Edit your SQL statement. Execute SQL from SQL*Plus. Save SQL statements to files and append SQL statements to files. Execute saved files. Load commands from file to buffer to edit. Overview of SQL*Plus

I-19 Copyright  Oracle Corporation, All rights reserved. Logging In to SQL*Plus From Windows environment:From Windows environment: From command line:From command line: sqlplus [username[/password sqlplus [username[/password From Windows environment:From Windows environment: From command line:From command line: sqlplus [username[/password sqlplus [username[/password

I-20 Copyright  Oracle Corporation, All rights reserved. Tables Used in the Course EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO KING PRESIDENT 17-NOV BLAKE MANAGER MAY CLARK MANAGER JUN JONES MANAGER APR MARTIN SALESMAN SEP ALLEN SALESMAN FEB TURNER SALESMAN SEP JAMES CLERK DEC WARD SALESMAN FEB FORD ANALYST DEC SMITH CLERK DEC SCOTT ANALYST DEC ADAMS CLERK JAN MILLER CLERK JAN EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO KING PRESIDENT 17-NOV BLAKE MANAGER MAY CLARK MANAGER JUN JONES MANAGER APR MARTIN SALESMAN SEP ALLEN SALESMAN FEB TURNER SALESMAN SEP JAMES CLERK DEC WARD SALESMAN FEB FORD ANALYST DEC SMITH CLERK DEC SCOTT ANALYST DEC ADAMS CLERK JAN MILLER CLERK JAN EMPDEPT DEPTNO DNAME LOC ACCOUNTING NEW YORK 20 RESEARCH DALLAS 30 SALES CHICAGO 40 OPERATIONS BOSTON DEPTNO DNAME LOC ACCOUNTING NEW YORK 20 RESEARCH DALLAS 30 SALES CHICAGO 40 OPERATIONS BOSTON GRADE LOSAL HISAL GRADE LOSAL HISAL SALGRADE

I-21 Copyright  Oracle Corporation, All rights reserved. Displaying Table Structure Use the SQL*Plus DESCRIBE command to display the structure of a table. DESC[RIBE] tablename

I-22 Copyright  Oracle Corporation, All rights reserved. Displaying Table Structure SQL> DESCRIBE dept Name Null? Type DEPTNO NOT NULL NUMBER(2) DNAME VARCHAR2(14) LOC VARCHAR2(13) Name Null? Type DEPTNO NOT NULL NUMBER(2) DNAME VARCHAR2(14) LOC VARCHAR2(13)

Copyright  Oracle Corporation, All rights reserved. Writing Basic SQL Statements

I-24 Copyright  Oracle Corporation, All rights reserved. Capabilities of SQL SELECT Statements Selection Projection Table 1 Table 2 Table 1 Join

I-25 Copyright  Oracle Corporation, All rights reserved. Basic SELECT Statement SELECT[DISTINCT] {*, column [alias],...} FROMtable; SELECT[DISTINCT] {*, column [alias],...} FROMtable; SELECT identifies what columns FROM identifies which table SELECT identifies what columns FROM identifies which table

I-26 Copyright  Oracle Corporation, All rights reserved. Writing SQL Statements SQL statements are not case sensitive. SQL statements can be on one or more lines. Keywords cannot be abbreviated or split across lines. Clauses are usually placed on separate lines. Tabs and indents are used to enhance readability. SQL statements are not case sensitive. SQL statements can be on one or more lines. Keywords cannot be abbreviated or split across lines. Clauses are usually placed on separate lines. Tabs and indents are used to enhance readability.

I-27 Copyright  Oracle Corporation, All rights reserved. Selecting All Columns DEPTNO DNAME LOC ACCOUNTING NEW YORK 20 RESEARCH DALLAS 30 SALES CHICAGO 40 OPERATIONS BOSTON SQL> SELECT * 2 FROM dept;

I-28 Copyright  Oracle Corporation, All rights reserved. Selecting Specific Columns DEPTNO LOC NEW YORK 20 DALLAS 30 CHICAGO 40 BOSTON SQL> SELECT deptno, loc 2 FROM dept;

I-29 Copyright  Oracle Corporation, All rights reserved. Column Label Defaults Default justification – Left: Date and character data – Right: Numeric data Default display: Uppercase Default justification – Left: Date and character data – Right: Numeric data Default display: Uppercase

I-30 Copyright  Oracle Corporation, All rights reserved. Arithmetic Expressions Create expressions on NUMBER and DATE data types by using arithmetic operators. Operator + - * / Description Add Subtract Multiply Divide

I-31 Copyright  Oracle Corporation, All rights reserved. Using Arithmetic Operators SQL> SELECT ename, sal, sal FROMemp; ENAME SAL SAL KING BLAKE CLARK JONES MARTIN ALLEN rows selected.

I-32 Copyright  Oracle Corporation, All rights reserved. Operator Precedence Multiplication and division take priority over addition and subtraction. Operators of the same priority are evaluated from left to right. Parentheses are used to force prioritized evaluation and to clarify statements. Multiplication and division take priority over addition and subtraction. Operators of the same priority are evaluated from left to right. Parentheses are used to force prioritized evaluation and to clarify statements. ** //++__

I-33 Copyright  Oracle Corporation, All rights reserved. Operator Precedence SQL> SELECT ename, sal, 12*sal FROM emp; ENAME SAL 12*SAL KING BLAKE CLARK JONES MARTIN ALLEN rows selected.

I-34 Copyright  Oracle Corporation, All rights reserved. Using Parentheses SQL> SELECT ename, sal, 12*(sal+100) 2 FROM emp; ENAME SAL 12*(SAL+100) KING BLAKE CLARK JONES MARTIN rows selected.

I-35 Copyright  Oracle Corporation, All rights reserved. Defining a Null Value A null is a value that is unavailable, unassigned, unknown, or inapplicable. A null is not the same as zero or a blank space. A null is a value that is unavailable, unassigned, unknown, or inapplicable. A null is not the same as zero or a blank space. SQL> SELECT ename, job, comm 2 FROMemp; ENAME JOB COMM KING PRESIDENT BLAKE MANAGER... TURNER SALESMAN rows selected.

I-36 Copyright  Oracle Corporation, All rights reserved. Null Values in Arithmetic Expressions Arithmetic expressions containing a null value evaluate to null. SQL> select ename NAME, 12*sal+comm 2 from emp 3 WHERE ename='KING'; NAME 12*SAL+COMM KING

I-37 Copyright  Oracle Corporation, All rights reserved. Defining a Column Alias Renames a column heading Is useful with calculations Immediately follows column name; optional AS keyword between column name and alias Requires double quotation marks if it contains spaces or special characters or is case sensitive Renames a column heading Is useful with calculations Immediately follows column name; optional AS keyword between column name and alias Requires double quotation marks if it contains spaces or special characters or is case sensitive

I-38 Copyright  Oracle Corporation, All rights reserved. Using Column Aliases SQL> SELECT ename AS name, sal salary 2 FROM emp; NAME SALARY SQL> SELECT ename "Name", 2 sal*12 "Annual Salary" 3 FROM emp; Name Annual Salary

I-39 Copyright  Oracle Corporation, All rights reserved. Concatenation Operator Concatenates columns or character strings to other columns Is represented by two vertical bars (||) Creates a resultant column that is a character expression Concatenates columns or character strings to other columns Is represented by two vertical bars (||) Creates a resultant column that is a character expression

I-40 Copyright  Oracle Corporation, All rights reserved. Using the Concatenation Operator SQL> SELECTename||job AS "Employees" 2 FROM emp; Employees KINGPRESIDENT BLAKEMANAGER CLARKMANAGER JONESMANAGER MARTINSALESMAN ALLENSALESMAN rows selected.

I-41 Copyright  Oracle Corporation, All rights reserved. Literal Character Strings A literal is a character, expression, or number included in the SELECT list. Date and character literal values must be enclosed within single quotation marks. Each character string is output once for each row returned. A literal is a character, expression, or number included in the SELECT list. Date and character literal values must be enclosed within single quotation marks. Each character string is output once for each row returned.

I-42 Copyright  Oracle Corporation, All rights reserved. Using Literal Character Strings Employee Details KING is a PRESIDENT BLAKE is a MANAGER CLARK is a MANAGER JONES is a MANAGER MARTIN is a SALESMAN rows selected. Employee Details KING is a PRESIDENT BLAKE is a MANAGER CLARK is a MANAGER JONES is a MANAGER MARTIN is a SALESMAN rows selected. SQL> SELECT ename||' '||'is a'||' '||job 2 AS "Employee Details" 3 FROM emp;

I-43 Copyright  Oracle Corporation, All rights reserved. Duplicate Rows The default display of queries is all rows, including duplicate rows. SQL> SELECT deptno 2 FROM emp; SQL> SELECT deptno 2 FROM emp; DEPTNO rows selected.

I-44 Copyright  Oracle Corporation, All rights reserved. Eliminating Duplicate Rows Eliminate duplicate rows by using the DISTINCT keyword in the SELECT clause. SQL> SELECT DISTINCT deptno 2 FROM emp; DEPTNO

I-45 Copyright  Oracle Corporation, All rights reserved. SQL*Plus Editing Commands A[PPEND] text C[HANGE] / old / new C[HANGE] / text / CL[EAR] BUFF[ER] DEL DEL n DEL m n A[PPEND] text C[HANGE] / old / new C[HANGE] / text / CL[EAR] BUFF[ER] DEL DEL n DEL m n

I-46 Copyright  Oracle Corporation, All rights reserved. SQL*Plus Editing Commands I[NPUT] I[NPUT] text L[IST] L[IST] n L[IST] m n R[UN] n n text 0 text I[NPUT] I[NPUT] text L[IST] L[IST] n L[IST] m n R[UN] n n text 0 text

I-47 Copyright  Oracle Corporation, All rights reserved. SQL*Plus File Commands SAVE filename GET filename START filename EDIT filename SPOOL filename EXIT SAVE filename GET filename START filename EDIT filename SPOOL filename EXIT

I-48 Copyright  Oracle Corporation, All rights reserved. Practice Overview Selecting all data from different tables. Describing the structure of tables. Performing arithmetic calculations and specifying column names. Using SQL*Plus editor. Selecting all data from different tables. Describing the structure of tables. Performing arithmetic calculations and specifying column names. Using SQL*Plus editor.

I-49 Copyright  Oracle Corporation, All rights reserved.

I-50 Copyright  Oracle Corporation, All rights reserved.

I-51 Copyright  Oracle Corporation, All rights reserved.

I-52 Copyright  Oracle Corporation, All rights reserved.

Restricting and Sorting Data

I-54 Copyright  Oracle Corporation, All rights reserved. Limiting Rows Using a Selection “…retrieve all employees in department 10” EMP EMPNO ENAME JOB... DEPTNO 7839KINGPRESIDENT BLAKEMANAGER CLARKMANAGER JONESMANAGER EMP EMPNO ENAME JOB... DEPTNO 7839KINGPRESIDENT CLARKMANAGER MILLERCLERK 10

I-55 Copyright  Oracle Corporation, All rights reserved. Limiting Rows Selected Restrict the rows returned by using the WHERE clause. The WHERE clause follows the FROM clause. Restrict the rows returned by using the WHERE clause. The WHERE clause follows the FROM clause. SELECT[DISTINCT] {*, column [alias],...} FROM table [WHEREcondition(s)];

I-56 Copyright  Oracle Corporation, All rights reserved. Using the WHERE Clause SQL> SELECT ename, job, deptno 2 FROM emp 3 WHERE job='CLERK'; ENAME JOB DEPTNO JAMES CLERK 30 SMITH CLERK 20 ADAMS CLERK 20 MILLER CLERK 10

I-57 Copyright  Oracle Corporation, All rights reserved. Character Strings and Dates Character strings and date values are enclosed in single quotation marks Character values are case-sensitive and date values are format-sensitive Default date format is 'DD-MON-YY' Character strings and date values are enclosed in single quotation marks Character values are case-sensitive and date values are format-sensitive Default date format is 'DD-MON-YY' SQL> SELECTename, job, deptno 2 FROM emp 3 WHEREename = 'JAMES'; SQL> SELECTename, job, deptno 2 FROM emp 3 WHEREename = 'JAMES';

I-58 Copyright  Oracle Corporation, All rights reserved. Comparison Operators Operator = > >= < <= <> Meaning Equal to Greater than Greater than or equal to Less than Less than or equal to Not equal to

I-59 Copyright  Oracle Corporation, All rights reserved. Using the Comparison Operators SQL> SELECT ename, sal, comm 2 FROM emp 3 WHERE sal<=comm; ENAME SAL COMM MARTIN

I-60 Copyright  Oracle Corporation, All rights reserved. Other Comparison Operators Operator BETWEEN...AND... IN(list) LIKE IS NULL Meaning Between two values (inclusive) Match any of a list of values Match a character pattern Is a null value

I-61 Copyright  Oracle Corporation, All rights reserved. Using the BETWEEN Operator ENAME SAL MARTIN 1250 TURNER 1500 WARD 1250 ADAMS 1100 MILLER 1300 SQL> SELECTename, sal 2 FROM emp 3 WHEREsal BETWEEN 1000 AND 1500; Lower limit Higher limit Use the BETWEEN operator to display rows based on a range of values.

I-62 Copyright  Oracle Corporation, All rights reserved. Using the IN Operator Use the IN operator to test for values in a list. SQL> SELECTempno, ename, sal, mgr 2 FROM emp 3 WHEREmgr IN (7902, 7566, 7788); EMPNO ENAME SAL MGR FORD SMITH SCOTT ADAMS

I-63 Copyright  Oracle Corporation, All rights reserved. Using the LIKE Operator Use the LIKE operator to perform wildcard searches of valid search string values. Search conditions can contain either literal characters or numbers. – (%) denotes zero or many characters – ( _ ) denotes one character Use the LIKE operator to perform wildcard searches of valid search string values. Search conditions can contain either literal characters or numbers. – (%) denotes zero or many characters – ( _ ) denotes one character SQL> SELECTename 2 FROM emp 3 WHEREename LIKE 'S%';

I-64 Copyright  Oracle Corporation, All rights reserved. Using the LIKE Operator You can combine pattern matching characters. You can use the ESCAPE identifier to search for “%” or “_”. You can combine pattern matching characters. You can use the ESCAPE identifier to search for “%” or “_”. SQL> SELECTename 2 FROMemp 3 WHEREename LIKE '_A%'; ENAME JAMES WARD

I-65 Copyright  Oracle Corporation, All rights reserved. Using the IS NULL Operator Test for null values with the IS NULL operator SQL> SELECT ename, mgr 2 FROM emp 3 WHERE mgr IS NULL; ENAME MGR KING

I-66 Copyright  Oracle Corporation, All rights reserved. Logical Operators Operator AND OR NOT Meaning Returns TRUE if both component conditions are TRUE Returns TRUE if either component condition is TRUE Returns TRUE if the following condition is FALSE

I-67 Copyright  Oracle Corporation, All rights reserved. Using the AND Operator AND requires both conditions to be TRUE. SQL> SELECT empno, ename, job, sal 2 FROM emp 3 WHERE sal>= AND job='CLERK'; EMPNO ENAME JOB SAL ADAMS CLERK MILLER CLERK 1300

I-68 Copyright  Oracle Corporation, All rights reserved. Using the OR Operator OR requires either condition to be TRUE. SQL> SELECT empno, ename, job, sal 2 FROM emp 3 WHERE sal>= OR job='CLERK'; EMPNO ENAME JOB SAL KING PRESIDENT BLAKE MANAGER CLARK MANAGER JONES MANAGER MARTIN SALESMAN rows selected.

I-69 Copyright  Oracle Corporation, All rights reserved. Using the NOT Operator SQL> SELECT ename, job 2 FROM emp 3 WHERE job NOT IN ('CLERK','MANAGER','ANALYST'); ENAME JOB KING PRESIDENT MARTIN SALESMAN ALLEN SALESMAN TURNER SALESMAN WARD SALESMAN

I-70 Copyright  Oracle Corporation, All rights reserved. Rules of Precedence Override rules of precedence by using parentheses. Order EvaluatedOperator 1All comparison operators 2NOT 3AND 4OR

I-71 Copyright  Oracle Corporation, All rights reserved. Rules of Precedence ENAME JOB SAL KING PRESIDENT 5000 MARTIN SALESMAN 1250 ALLEN SALESMAN 1600 TURNER SALESMAN 1500 WARD SALESMAN 1250 ENAME JOB SAL KING PRESIDENT 5000 MARTIN SALESMAN 1250 ALLEN SALESMAN 1600 TURNER SALESMAN 1500 WARD SALESMAN 1250 SQL> SELECT ename, job, sal 2 FROM emp 3 WHERE job='SALESMAN' 4 OR job='PRESIDENT' 5 AND sal>1500;

I-72 Copyright  Oracle Corporation, All rights reserved. Rules of Precedence ENAME JOB SAL KING PRESIDENT 5000 ALLEN SALESMAN 1600 ENAME JOB SAL KING PRESIDENT 5000 ALLEN SALESMAN 1600 Use parentheses to force priority. SQL> SELECT ename, job, sal 2 FROM emp 3 WHERE (job='SALESMAN' 4 OR job='PRESIDENT') 5 AND sal>1500;

I-73 Copyright  Oracle Corporation, All rights reserved. ORDER BY Clause Sort rows with the ORDER BY clause – ASC: ascending order, default – DESC: descending order The ORDER BY clause comes last in the SELECT statement. Sort rows with the ORDER BY clause – ASC: ascending order, default – DESC: descending order The ORDER BY clause comes last in the SELECT statement. SQL> SELECT ename, job, deptno, hiredate 2 FROM emp 3 ORDER BY hiredate; ENAME JOB DEPTNO HIREDATE SMITH CLERK DEC-80 ALLEN SALESMAN FEB rows selected.

I-74 Copyright  Oracle Corporation, All rights reserved. Sorting in Descending Order SQL> SELECT ename, job, deptno, hiredate 2 FROM emp 3 ORDER BY hiredate DESC; ENAME JOB DEPTNO HIREDATE ADAMS CLERK JAN-83 SCOTT ANALYST DEC-82 MILLER CLERK JAN-82 JAMES CLERK DEC-81 FORD ANALYST DEC-81 KING PRESIDENT NOV-81 MARTIN SALESMAN SEP rows selected.

I-75 Copyright  Oracle Corporation, All rights reserved. Sorting by Column Alias SQL> SELECT empno, ename, sal*12 annsal 2 FROM emp 3 ORDER BY annsal; EMPNO ENAME ANNSAL SMITH JAMES ADAMS MARTIN WARD MILLER TURNER rows selected.

I-76 Copyright  Oracle Corporation, All rights reserved. Sorting by Multiple Columns The order of ORDER BY list is the order of sort. You can sort by a column that is not in the SELECT list. SQL> SELECTename, deptno, sal 2 FROM emp 3 ORDER BY deptno, sal DESC; ENAME DEPTNO SAL KING CLARK MILLER FORD rows selected.

I-77 Copyright  Oracle Corporation, All rights reserved. Summary SELECT[DISTINCT] {*, column [alias],...} FROM table [WHEREcondition(s)] [ORDER BY{column, expr, alias} [ASC|DESC]];

I-78 Copyright  Oracle Corporation, All rights reserved. Practice Overview Selecting data and changing the order of rows displayed Restricting rows by using the WHERE clause Using the double-quotation-marks in column aliases Selecting data and changing the order of rows displayed Restricting rows by using the WHERE clause Using the double-quotation-marks in column aliases

I-79 Copyright  Oracle Corporation, All rights reserved.

I-80 Copyright  Oracle Corporation, All rights reserved.

I-81 Copyright  Oracle Corporation, All rights reserved.

I-82 Copyright  Oracle Corporation, All rights reserved.