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Explain the concepts of relational data model?
Relational Data Model - The relational model was first introduced through Prof. E.F. Codd of the IBM Research in the year 1970 and attracted immediate attention because of its simplicity and mathematical foundation. The model uses the concept of a mathematical relation (such as a table of values) as its primary building block, and has its theoretical basis within set theory and first-order predicate logic. The relational model represents the database as a collection of relations. The relational model such as all other models consists of three basic elements:
Multiple-mode locks : It offers two locks: exclusive locks and shared locks. But why do we require these two locks? There are a lot of transactions in the database system that neve
Using Column aliases Example: To print column names as NAME and ANNUAL SALARY SELECT ENAME "NAME", SAL*12 "ANNUAL SALARY" FROM EMP;
The Maximum no of key fields that can be used in a header is?? 50
What is difference among mysql_connect and mysql_pconnect? Mysql_connect() opens a new connection to the database while mysql_pconnect() opens persistent connection to the data
Give the limitations of SQL authorization. The code for checking authorization becomes intermixed with the rest of the application code. Implementing authorization by applic
What is the most significant feature that does not directly map into programming language structures? Why? Association, since there are complex types of association, like as qu
What is serialization? Where it is used and why? Serialization is a basic term used for mechanisms which enable objects and object structures to be converted into portable for
Atomicity: It describes a transaction to be a one unit of processing. We can also say either a transaction will be finished completely or not at all. In the transaction example 1
Question: (a) One of the steps in the five-step problem-solving model is implementation. Implementation is considered a key step in the problem-solving model. A problem may be
What is Foreign Key Foreign Key: Sometimes we may have to work with an attribute that does not have a primary key of its own. To recognize its rows, we have to use the primar
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