CSE NOTES

Process control block -Each process is represented in the operating system by the process control block also called as task control block. -It contains many pieces of information associated with a specific process include these Process states: The state may be new/ready,running,waiting,haltered and soon. Program counter: The counter can be indicate to the address of the next instruction to be executed for this process. CPU registers: The register vary in number and type depending in the computer or architecture .they includes the accumulator,index register,stack pointer , general purpose of register. Memory management information: It may be includes such information as the value of the base and limit register, the page tables or segment tables depending on the memory system used by the operating system. Accounting information: It includes the account of the CPU and real time used,time limits account number,job or process number and soon. I/O status inf...

-Process state means current activity of process. -When process is execute it changes the state generally state of process is determine by the current activity of process. -Each process may be in one of the following state. new- the process is being is oriented. ready- the process is waiting to be assigned to the processor. waiting - the process is waiting for some event (I/O operation) to occur. running - the process is being executed.  terminated -the process as finished the execution. process state diagram: -The pictorial is represented to the process changing from one process to another process during       there  execution is known as process state diagram. -A process can be change for one process in the following manner. new ready: The operating system(os) create a process and prepares the process to be executed ,then the os moved the process into the ready queue.  ready running: When it is time to select a pro...

Queries in SQL Data types character: -This types of data types store the characters string in fixed length. -The size in brackets determine the no of characters the shell can hold. -character data types is 255 characters. var character(size)/var char 2 (size): -This character is used to store variable length alpha numeric data. -Var char is 2000 character. date: -Date data type is used to represent to the data / time. -The standard. format is dd/mm/yy. Number: -The number data type is used to store number no of any magnitude may be stored up to 38 bit.  

Data Model -Data model is used to describe of the structure of the database and to hide of the storage details and present the users with the conceptual view of the database. -In other words how to store data in the database is known as data model. -There are three types of data model:                                                             hierarchical data model                                                             network data model                                                             relational data model Hie...

E-R diagram -E-R diagram is the entity relationship diagram. -E-R diagram can express the logical structure of the database graphically. -E-R diagram can consist of the following major components. -The entity sets are represented by the rectangular. -The attribute are represented by the ellipse. -The relationship are represented by the diamond and rhombus. -Line is used to link attribute to entity sets and entity sets to relationship sets. -double ellipse is represented to composite attributes. -Dotted ellipse is represented to dotted derived attributes. It is represented to composite attributes. -Key attributes. -Double rectangle represented to work of entities. -Double line indicate to the particularization of an entity set in the relationship sets. -One to ...

Mapping constraints  -A mapping constraints is data constraints that express the number of entity to which another entity can be related via a relationship sets.  -It is most useful in describing relationship sets that involve more than two entity sets.   -There are four types of mapping constraints. -one to one  -one to many -many to one  -many to many one to one: Let us consider two entity sets A and B. An entity in A is associated with at most one entity in B.An entity in B is associated with at most one entity in A. one to many: Let us consider two entity sets A and B. An entity in A is associated with any number (0 or more) of the entity in B and An entity in B is associated with at most one entity in A. many to one : let us consider two entity sets A and B. An entity in A is associated with at most one entity in B and an entity in B is associated with any number of the ent...

Attribute  -Properties or character of the entity is called attribute  the attribute are the descriptive properties   proceed by the each member of the entity set  -ex The possible attribute of the customer entity are customer city, customer id, loan. \-There are 4 types of the entity :                                                      -single value and multi value attributes                                                       -simple and composite attributes                                                      -derived attributes  ...