(11-07-21)DATA TYPES IN BRIEF

 

DATA TYPES IN SQL:

1) NUMERIC  

2) DATE AND TIME

3)STRING TYPES

NUMERIC:

#INT :  NORMAL SIZED INTEGER WHICH CAN BE SIGNED OR UNSIGNED.                                                 SPECIFY WIDTH UPTO 11 DIGITS.

#FLOAT : A FLOATING POINT NUMBER THAT CANNOT BE UNSIGNED.                                                       BY DEFAULT IT IS 10,2 THAT IS 2 IS THE NUMBER OF DECIMALS AND 10 IS                             THE TOTAL NUMBER OF DIGITS(INCLUDING DECIMALS).                                                            DECIMAL PRECISION CAN GO TO 24 PLACES FOR A FLOAT.

DATE AND TIME:

#DATE : A DATE IN YYYY-MM-DD FORMAT.

#DATETIME : A DATE AND TIME COMBINATION IN YYYY-MM-DD   HH:MM:SS.

#TIME : TIME IN  HH:MM:SS.

STRING:

#CHAR : FIXED LENGTH STRING BETWEEN   1 AND 255    CHARACTERS.

#VARCHAR : VARIABLE LENGTH STRING BETWEEN   1 AND 255    CHARACTERS.

(8-7-21)MYSQL BASICS

                       

ADVANTAGES OF DBMS(DATABASE MANAGEMENT SYSTEM)

(1) REDUCES DATA REDUNDANCY TO A LARGE EXTENT

(2)  CAN CONTROL DATA INCONSISTENCY TO A LARGE EXTENT

(3) FACILITATES SHARING OF DATA

(4) ENFORCE STANDARDS

(5) DATABASE CAN ENSURE DATA SECURITY

(6) ENSURE DATA INDEPENDENCE

#IMPORTANT TERMS:-

-> DATA CONSTRAINTS :

DATA CONSTRAINTS ARE SET OF RULES THAT DEFINE VALID DATA

EG:- PRIMARY CONSTRAINTS ARE-NOT NULL , PRIMARY KEY , UNIQUE , CHECK , DEFAULT , FOREIGN KEY .

-> QUERY : 

A QUERY IS A TYPE OF COMMAND THAT RETRIEVES DATA FROM A DATABASE STORED ON A SERVER.

EG:- SELECT QUERY ,  ACTION QUERY .

-> DATA MANIPULATION : 

DATA MANIPULATION IS THE RESULT OF ACTION QUERIES .

EG:- INSERT , UPDATE , DELETE .

# RELATIONAL DATABASE MODEL:

IN A RELATIONAL DATA MODEL, THE DATA IS ORGANISED INTO TABLES(ROWS AND COLUMNS).THESE TABLES ARE CALLED RELATIONS.A ROW IN A TABLE REPRESENTS A RELATIONSHIP AMONG A SET OF VALUES.

EG OF COMMON RELATIONAL DATABASE MANAGEMENT SYSTEM:-

MICROSOFT SQL SERVER , MYSQL , ORACLE DATABASE , IBM INFORMIX , IBM DB2 .

(5-07-21)STARTING WITH MYSQL

DATABASE:                                                                                                                                                 A  DATABASE  MAY  BE  DEFINED  AS  A  COLLECTION  OF  INTERRELATED  DATA STORED  TOGETHER  TO  SERVE  MULTIPLE  APPLICATIONS .

FILE-BASED SYSTEM:                                                                                                                             A  FILE  BASED  SYSTEM  OR  A  FLAT FILE OR A FLAT DATABASE STORES ALL THE DATA IN ONE BIG FILE.

LIMITATIONS OF FILED-BASED APPROACH:

1) DATA REDUNDANCY :  REFERS TO THE STORAGE OF THE SAME DATA MULTIPLE TIMES.

2) DATA INCONSISTENCY : MULTIPLE COPIES OF THE SAME DATA CAUSED BY DATA REDUNDANCY IS CALLED DATA INCONSISTENCY.

3) DATA ISOLATION : REFERS TO A SITUATION WHERE DATA OF ONE FILE CANNOT BE MAPPED TO OTHER RELATED FILE IN THE ABSENCE OF LINKS OR MAPPINGS OR COMMON FORMATS.

4) DATA DEPENDENCE : THE CLOSE RELATIONSHIP BETWEEN DATA STORED IN FILES AND THE SOFTWARE PROGRAMS THAT UPDATE AND MAINTAIN THOSE FILES IS CALLED DATA DEPENDENCE.

# OTHER DEFINATION OF DATABASE : *(VERY IMPORTANT)

WORDS COLOURED IN RED ARE IMPOSTANT.

A DATABASE IS AN  ORGANISED COLLECTION OF  STRUCTURED  INFORMATION ,OR DATA,TYPICALLY STORED ELECTRONICALLY  IN  A  COMPUTER  SYSTEM  AT  A CENTRAL  LOCATION.

# DATABASE MANAGEMENT SYSYTEM (DBMS)

DBMS IS A SOFTWARE SYSTEM  DESIGNED TO MAINTAIN A DATABASE AND PROVIDE DATA MANAGEMENT SERVICE.

(3-07-21)SIMPLE PROGRAMS(PART-3)

Q1) WRITE A PROGRAM TO INPUT TWO NUMBERS AND SWAP THEM:-

CODE:-

HERE, N1 AND N2 I HAVE TAKEN AS A VARIABLE ,TO TAKE INPUT FROM THE USERS,AND IN THE 4TH LINE  I HAVE ASSIGNED THE INTERCHANGED VALUE SO THAT THE VALUES IS SWAPPED AND N1 WILL BECOME N2 AND N2 WILL BECOME N1.

ALSO,I HAVE PRINTED THEM SEPERATELY . LIKE- ORIGINAL NUMBERS AS WELL AS NUMBERS AFTER SWAPING.

OUTPUT:-

TRY  IT  YOURSELF !!  : -

n1=int(input("ENTER NUMBER 1 : "))
n2=int(input("ENTER NUMBER 2 : "))
print("ORIGINAL NUMBERS : ",n1,n2)
n1,n2=n2,n1
print("AFTER SWAPING : ",n1,n2)

Q2) WRITE A PROGRAM TO INPUT NUMBERS FROM USER AND SWAP THEM IN SUCHA WAY THAT: THE THE 1ST NUMBER BECOME 2ND NUMBER,2ND NUMBER BECOME THE 3RD NUMBER AND 3RD NUMBER BECOME THE 1ST NUMBER. 

CODE:-

HERE, I HAVE WRITTEN COMMAND USING INPUT FUNCTION TO TAKE VALUES FROM THE USER.NOW FIRST I WILL PRINT THE ORIGINAL NUMBERS IN THE SEQUENCE . AFTER THAT I HAD ASSIGNED THE VALUES TO SWAP THEM WHICH WAS GIVEN THE QUESTION OF SWAP ORDER. NOW I HAVE PRINTED THEM AFTER SWAPING FROM THE LAST COMMAND.

OUTPUT:-

HERE, AS U CAN SEE,,

X(1ST NUMBER)=Y(2ND NUMBER)

Y(2ND NUMBER)=Z(3RD NUMBER) 

Z(3RD NUMBER)=X(1ST NUMBER)

TRY  IT  YOURSELF  !! : -

x=int(input("ENTER NUMBER 1 : "))
y=int(input("ENTER NUMBER 2 : "))
z=int(input("ENTER NUMBER 2 : "))
print("ORIGINAL NUMBERS : ",x ,y ,z)
x ,y ,z=y ,z ,x
print("AFTER SWAPING : ",x ,y ,z)

PRACTICE QUESTION: 

TELL ME THE ANSWER OF THIS IN THE COMMENTS SECTION !!!

TELL ME THE OUTPUT FOR THE FOLLOWING CODE:                                                 n1,n2=5,7                                                                                                                                       n3=n1+n2                                                                                                                                           n4=n4+2                                                                                                                               print(n1,n2,n3,n4)

👍👀

(2-07-21)SIMPLE PROGRAMS (PART-2)

 

Q1). WRITE A PROGRAM  TO INPUT A NUMBER AND PRINT ITS CUBE:

CODE:-

HERE, NUM I HAVE TAKEN AS A VARIABLE FROM WHICH IT WILL INPUT VALUES. ALSO CUBE IS VARIABLE WHICH WILL PERFORM 3 TIMES MULTIPLICATION THAT IS, CUBE.

CUBE:-

DO  IT  YOURSELF  !!  : - 

num=int(input("ENTER THE NUMBER: "))                                                    cube=num*num*num                                                                                                    print("NUMBER IS : ", num)                                                                                                 print("ITS CUBE IS : ", cube)

Q2) WRITE A PROGRAM TO INPUT A VALUE IN KILOMETRES AND CONVERT IT INTO MILES    (1 KM = 0.621371)

CODE:-

OUTPUT:-

TRY  IT  YOURSELF  !!  :  -

km=int(input("ENTER KILOMETRES: "))                                                                  miles=km*0.621371                                                                                                            print("KILOMETRES: ",km)                                                                                                  print("MILES: ",miles)

👍😊