Restricting and sorting data 16 May 201516 May 201516 May 20151 Created By Pantharee Sawasdimongkol.

Restricting and sorting Restricting and sorting datadata

April 18, 2023April 18, 2023 11Created By Pantharee Created By Pantharee

SawasdimongkolSawasdimongkol

objectivesobjectives

After completing this lesson, you should After completing this lesson, you should

be able to do the following:be able to do the following: Limit the rows retrieved by a queryLimit the rows retrieved by a query Sort the rows retrieved by a querySort the rows retrieved by a query



Limiting Rows Using a SelectionLimiting Rows Using a Selection

EMPNEMPNOO ENAMEENAME JOBJOB ………… DEPTNODEPTNO

78397839 KINGKING PRESIDENTPRESIDENT 1010

76987698 BLAKEBLAKE MANAGERMANAGER 3030

77827782 CLARKCLARK MANAGERMANAGER 1010

75667566 JONESJONES MANAGERMANAGER 2020

EMPNOEMPNO ENAMEENAME JOBJOB ………… DEPTNODEPTNO

78397839 KINGKING PRESIDENTPRESIDENT 1010

77827782 CLARKCLARK MANAGERMANAGER 1010

79347934 MILLERMILLER CLERKCLERK 1010

EMP

EMP

“…retrieve all

employees

In department 10”



Limiting Rows SelectedLimiting Rows Selected

Restrict the rows returned by using theRestrict the rows returned by using the

WHERE clauseWHERE clause

SELECT [ DISTINCT ] { * } column [ alias] , …}FROM table[WHERE condition (s) ] ;

The WHERE clause follows the FROM The WHERE clause follows the FROM clause.clause.



Using the WHERE ClauseUsing the WHERE Clause

SQL> SELECT ename , job , deptno 2 FROM emp 3 WHERE job = ‘CLERK’ ;

ENAMEENAME JOBJOB DEPTNODEPTNO

-------------------------- ---------------------------- --------------------------

JAMESJAMES

SMITHSMITH

ADAMSADAMS

MILLERMILLER

CLERKCLERK

CLERKCLERK

CLERKCLERK

CLERKCLERK

3030

2020

2020

1010



Character Strings and DatesCharacter Strings and Dates

Character Strings and date values are Character Strings and date values are

Enclosed in single quotation marks.Enclosed in single quotation marks. Character values are case sensitive andCharacter values are case sensitive and

Data values are format sensitive.Data values are format sensitive. The default data format is DD-MON-YY.The default data format is DD-MON-YY.

SQL> SELECT ename , job , deptno 2 FROM emp; 3 WHERE ename = ‘JAMES’ ;



Comparison OperatorsComparison Operators

Operator Meaning

= Equal to

> Greater than

>= Greater than or equal to

< Less than

<= Less than or equal to

< > , != Not equal to



Using the ComparisonUsing the ComparisonOperatorsOperators

SQL> SELECT ename , sal , comm 2 FROM emp 3 WHERE sal <= comm;

ENAMEENAME SALSAL COMMCOMM

-------------------------- ---------------------------- --------------------------

MARTINMARTIN

12501250 14001400



Other Comparison operatorsOther Comparison operators

Operator Meaning

BETWEEN Between two values (inclusive)

…AND…

IN (list) Match any of a list of values

LIKE Match a character pattern

IS NULL Is a null value



Using the BETWEEN OperatorUsing the BETWEEN Operator Use the Use the BETWEENBETWEEN operator to display operator to displayRows based on a range of values.Rows based on a range of values.

SQL> SELECT ename , sal 2 FROM emp 3 WHERE sal BETWEEN 1000 AND 1500 ;

ENAME SAL---------- ----------WARD 1250MARTIN 1250TURNER 1500ADAMS 1100MILLER 1300

Lower limit

Higherlimit



Using the IN OperatorUsing the IN Operator

Use the Use the ININ operator to test for values in a operator to test for values in a list.list.

SQL> SELECT empno , ename , sal , mgr 2 FROM emp 3 WHERE mgr IN ( 7902 , 7566 , 7788 ) ;

EMPNO ENAME SAL MGR----------- --------- ---------- ---------- 7369 SMITH 800 7902 7788 SCOTT 3000 7566 7876 ADAMS 1100 7788 7902 FORD 3000 7566



Using the LIKE OperatorUsing the LIKE Operator UseUse the the LIKELIKE operator to perform wildcard operator to perform wildcard

searches of valid search string values.searches of valid search string values. Search conditions can contain either literalSearch conditions can contain either literal Characters or numbers.Characters or numbers.

-- % denotes zero or many characters. % denotes zero or many characters. -- _ denotes one characters. _ denotes one characters.

SQL> SELECT ename 2 FROM emp 3 WHERE ename LIKE ‘ S% ’ ;



Using the LIKE OperatorUsing the LIKE Operator You can combine pattern-matching characters.You can combine pattern-matching characters.

SQL> SELECT ename 2 FROM emp 3 WHERE ename LIKE ‘_A%’ ;

ENAME ---------------- MARTIN JAMES WARD

You can use the You can use the ESCAPEESCAPE( ( \\ ) identifier to search ) identifier to search for “%” or “_” .for “%” or “_” .



Using the IS NULL OperatorUsing the IS NULL Operator

Test for null values with the Test for null values with the IS NULL IS NULL

Operator.Operator.

SQL> SELECT ename , mgr 2 FROM emp 3 WHERE mgr IS NULL ;

ENAME MGR ---------------- ------------------ KING



Logical OperatorsLogical Operators

Operator Meaning

AND Returns TRUE if both component

conditions are TRUE

OR Returns TRUE if either component conditions are TRUE

NOT Returns TRUE if the component conditions are FALSE



Using the AND OperatorUsing the AND Operator

AND requires both conditions to be TRUEAND requires both conditions to be TRUE

SQL> SELECT empno , ename , job , sal 2 FROM emp 3 WHERE sal >= 1100 4 AND job = ‘CLERK’ ;

EMPNO ENAME JOB SAL----------- --------- ---------- ---------- 7876 ADAMS CLERK 1100 7934 MILLER CLERK 1300



Using the OR OperatorUsing the OR Operator

EMPNO ENAME JOB SAL----------- --------- ---------- ---------- 7839 KING PRESIDENT 50007782 CLARK MANAGER 24507566 JONES MANAGER 29757654 MARTIN SALESMAN 1250………7900 JAMES CLERK 950

14 rows selected.

OR requires either condition to be TRUE.OR requires either condition to be TRUE.

SQL> SELECT empno , ename , job , sal 2 FROM emp 3 WHERE sal >= 1100 4 OR job = ‘CLERK’ ;



Using the NOT OperatorUsing the NOT Operator

EMPNO JOB------------------- ----------------------KING PRESIDENTMARTIN SALESMANALLEN SALESMANTURNER SALESMANWARD SALESMAN

SQL> SELECT empno , job 2 FROM emp

3 WHERE job NOT IN ( ‘ CLERK ', ' MANAGER ', 'ANALYST’);



Rules of PrecedenceRules of Precedence

Order Evaluated Meaning

1 All comparison

operators

2 NOT

3 AND

4 OR

Override rules of precedence by using Override rules of precedence by using

parentheses.parentheses.




ENAME JOB SAL---------- ------------- ---------------------ALLEN SALESMAN 1600WARD SALESMAN 1250MARTIN SALESMAN 1250 KING PRESIDENT 5000TURNER SALESMAN 1500

SQL> SELECT ename , job , sal 2 FROM emp 3 WHERE job = 'SALESMAN' 4 OR job = 'PRESIDENT ' 5 AND sal > 1500;




Use parentheses to force priority.Use parentheses to force priority.

ENAME JOB SAL---------- --------- ----------ALLEN SALESMAN 1600KING PRESIDENT 5000

SQL> SELECT ename , job , sal 2 FROM emp 3 WHERE ( job='SALESMAN' 4 OR job='PRESIDENT') 5 AND sal > 1500;



ORDER BY ClauseORDER BY Clause SortSort rows with the ORDER BY clauserows with the ORDER BY clause

- ASC : ascending order,default- ASC : ascending order,default- DESC : descending order- DESC : descending order

The ORDER BY clause comes last in the The ORDER BY clause comes last in the SELECT statement.SELECT statement.

ENAME JOB DEPTNO HIREDATE---------- --------- -------------- -------------------SMITH CLERK 20 17-DEC-80ALLEN SALESMAN 30 20-FEB-81…….14 rows selected.

SQL> SELECT ename , job , deptno , hiredate 2 FROM emp 3 ORDER BY hiredate;



Sorting in Descending OrderSorting in Descending Order

ENAME JOB DEPTNO HIREDATE---------- --------- ---------------- ------------------ADAMS CLERK 20 23-MAY-87SCOTT ANALYST 20 19-APR-87MILLER CLERK 10 23-JAN-82JAMES CLERK 30 03-DEC-81FORD ANALYST 20 03-DEC-81KING PRESIDENT 10 17-NOV-81MARTIN SALESMAN 30 28-SEP-81…….14 rows selected.

SQL> SELECT ename , job , deptno, hiredate 2 FROM emp 3 ORDER BY hiredate DESC;



Sorting by column AliasSorting by column Alias

EMPNO ENAME ANNSAL--------- ---------------- ------------------ 7369 SMITH 9600 7900 JAMES 11400 7876 ADAMS 13200 7521 WARD 15000 7654 MARTIN 15000 7934 MILLER 15600 7844 TURNER 18000 …….14 rows selected.

SQL> SELECT empno , ename , sal*12 annsal 2 FROM emp 3 ORDER BY annsal;



Sorting by Multiple ColumnsSorting by Multiple Columns The order of ORDER BY list is the order of The order of ORDER BY list is the order of

sort.sort.

ENAME DEPTNO SAL---------- ---------- ----------KING 10 5000CLARK 10 2450MILLER 10 1300SCOTT 20 3000…….14 rows selected.

SQL> SELECT ename , deptno , sal 2 FROM emp 3 ORDER BY deptno , sal DESC ;



SummarySummary

SELECT [ DISTINCT ] { * } column [ alias ] , …}FROM table[WHERE condition (S) ][ ORDER BY {column , expr , alias} [ASC | DESC ] ] ;



Practice OverviewPractice Overview

Selecting data and changing the order of Selecting data and changing the order of rows displayedrows displayed

Restricting rows by using the WHERE Restricting rows by using the WHERE clauseclause

Using the double quotation marks in Using the double quotation marks in column aliasescolumn aliases



Restricting and sorting data 16 May 201516 May 201516 May 20151 Created By Pantharee Sawasdimongkol.

Documents

Transcript of Restricting and sorting data 16 May 201516 May 201516 May 20151 Created By Pantharee Sawasdimongkol.