Sql Server 2000

Question: Write a Role of Sql Server 2005 in XML Web Services?
Answer:- SQL Server 2005 create a standard method for getting the database engine using SOAP via HTTP. By this method, we can send SOAP/HTTP requests to SQL Server for executing T-SQL batch statements, stored procedures, extended stored procedures, and scalar-valued user-defined functions may be with or without parameters.

Question: What are the different types of Locks ?
Answer: There are three main types of locks that SQL Server
(1)Shared locks are used for operations that does not allow to change or update data, such as a SELECT statement.
(2)Update locks are used when SQL Server intends to modify a page, and later promotes the update page lock to an exclusive page lock before actually making the changes.
(3)Exclusive locks are used for the data modification operations, such as UPDATE, INSERT, or DELETE.

Question: Explain some SQL Server 2000 Query?
Answer: Here are some sql server 2000 query like Sql Insert Query, Delete Sql Query, Update Sql Query and Sql Create Query:
1) Sql Insert Query:
a) How to encrypt data by using Sql Insert Query.
--: insert into table_name(Tablecolumn1, tablecolumn2,. . . . .) values ('value1', pwdencrypt('value'),. . . .)

b) How to copy data from one table to another with the help of Sql Insert Query.
--: insert into table_name(column1,column2,. . . . ) select column1, column2, . . . . from table_name2

c) Sql Insert Query using where clause
--: insert into tablename(column1,column2) select column1,column2 from tablename2 where id=value.

Question: What is 'Write-ahead log' in Sql Server 2000 ?
Answer: Before understanding it we must have an idea about the transaction log files. These files are the files which holds the data for change in database .
Now we explain when we are doing some Sql Server 2000 query or any Sql query like Sql insert query,delete sql query,update sql query and change the data in sql server database it cannot change the database directly to table .Sql server extracts the data that is modified by sql server 2000 query or by sql query and places it in memory.Once data is stores in memory user can make changes to that a log file is gernated this log file is gernated in every five mintues of transaction is done. After this sql server writes changes to database with the help of transaction log files. This is called Write-ahead log.
Question: What do u mean by Extents and types of Extends ?
Answer: An Extent is a collection of 8 sequential pages to hold database from becoming fregmented. Fragment means these pages relates to same table of database these also holds in indexing. To avoid for fragmentation Sql Server assign space to table in extents. So that the Sql Server keep upto date data in extents. Because these pages are continously one after another. There are usually two types of extends:-Uniform and Mixed.
Uniform means when extent is own by a single object means all collection of 8 ages hold by a single extend is called uniform.
Mixed mean when more then one object is comes in extents is known as mixed extents.
Question: What is different in Rules and Constraints ?
Answer: Rules and Constraints are similar in functionality but there is a An little diffrence between them.Rules are used for backward compatibility . One the most exclusive diffrence is that we an bind rules to a datatypes whereas constraints are bound only to columns.So we can create our own datatype with the help of Rules and get the input according to that.
Question: What is defaults in Sql Server and types of Defaults ?
Answer: Defaults are used when a field of columns is allmost common for all the rows for example in employee table all living in delhi that value of this field is common for all the row in the table if we set this field as default the value that is not fill by us automatically fills the value in the field its also work as intellisense means when user inputing d it will automatically fill the delhi . There are two types of defaults object and definations.
Object deault:-These defaults are applicable on a particular columns . These are usually deined at the time of table designing.When u set the object default field in column state this column in automatically field when u left this filed blank.
Defination default:-When we bind the datatype with default let we named this as dotnet .Then every time we create column and named its datatype as dotnet it will behave the same that we set for dotnet datatype.
Question: What Is Database ?
Answer: A database is similar to a data file in that it is a storage place for data. Like a data file, a database does not present information directly to a user; the user runs an application that accesses data from the database and presents it to the user in an understandable format.Database systems are more powerful than data files in that data is more highly organized. In a well-designed database, there are no duplicate pieces of data that the user or application must update at the same time. Related pieces of data are grouped together in a single structure or record, and relationships can be defined between these structures and records.When working with data files, an application must be coded to work with the specific structure of each data file. In contrast, a database contains a catalog that applications use to determine how data is organized. Generic database applications can use the catalog to present users with data from different databases dynamically, without being tied to a specific data format. A database typically has two main parts: first, the files holding the physical database and second, the database management system (DBMS) software that applications use to access data. The DBMS is responsible for enforcing the database structure, including: • Maintaining relationships between data in the database. Ensuring that data is stored correctly, and that the rules defining data relationships are not violated. • Recovering all data to a point of known consistency in case of system failures.

Question: what is Relational Database ?
Answer: Although there are different ways to organize data in a database, relational databases are one of the most effective. Relational database systems are an application of mathematical set theory to the problem of effectively organizing data. In a relational database, data is collected into tables (called relations in relational theory). A table represents some class of objects that are important to an organization. For example, a company may have a database with a table for employees, another table for customers, and another for stores. Each table is built of columns and rows (called attributes and tuples in relational theory). Each column represents some attribute of the object represented by the table. For example, an Employee table would typically have columns for attributes such as first name, last name, employee ID, department, pay grade, and job title. Each row represents an instance of the object represented by the table. For example, one row in the Employee table represents the employee who has employee ID 12345. When organizing data into tables, you can usually find many different ways to define tables. Relational database theory defines a process called normalization, which ensures that the set of tables you define will organize your data effectively.

Question: What is Data Integrity and it's categories ?
Answer: Enforcing data integrity ensures the quality of the data in the database. For example, if an employee is entered with an employee_id value of 123, the database should not allow another employee to have an ID with the same value. If you have an employee_rating column intended to have values ranging from 1 to 5, the database should not accept a value of 6. If the table has a dept_id column that stores the department number for the employee, the database should allow only values that are valid for the department numbers in the company. Two important steps in planning tables are to identify valid values for a column and to decide how to enforce the integrity of the data in the column. Data integrity falls into these categories:
1) Entity integrity
2) Domain integrity
3) Referential integrity
4) User-defined integrity
Entity Integrity: Entity integrity defines a row as a unique entity for a particular table. Entity integrity enforces the integrity of the identifier column(s) or the primary key of a table (through indexes, UNIQUE constraints, PRIMARY KEY constraints, or IDENTITY properties).
Domain Integrity: Domain integrity is the validity of entries for a given column. You can enforce domain integrity by restricting the type (through data types), the format (through CHECK constraints and rules), or the range of possible values (through FOREIGN KEY constraints, CHECK constraints, DEFAULT efinitions, NOT NULL definitions, and rules).
Referential Integrity: Referential integrity preserves the defined relationships between tables when records are entered or deleted. In Microsoft® SQL Server™ 2000, referential integrity is based on relationships between foreign keys and primary keys or between foreign keys and unique keys (through FOREIGN KEY and CHECK constraints). Referential integrity ensures that key values are consistent across tables. Such consistency requires that there be no references to nonexistent values and that if a key value changes, all references to it change consistently throughout the database. When you enforce referential integrity, SQL Server prevents users from:
• Adding records to a related table if there is no associated record in the primary table.
• Changing values in a primary table that result in orphaned records in a related table.
• Deleting records from a primary table if there are matching related records.
For example, with the sales and titles tables in the pubs database, referential integrity is based on the relationship between the foreign key (title_id) in the sales table and the primary key (title_id) in the titles table.
User-Defined: Integrity User-defined integrity allows you to define specific business rules that do not fall into one of the other integrity categories. All of the integrity categories support user-defined integrity (all column- and table-level constraints in CREATE TABLE, stored procedures, and triggers).

Question: SQL Server runs on which TCP/IP port and From where can you change the default port?
Answer: SQL Server runs on port 1433 but we can also change it for better security and From the network Utility TCP/IP properties -->Port number.both on client and the server.
Question: What is the use of DBCC commands?
Answer: DBCC stands for database consistency checker. We use these commands to check the consistency of the databases, i.e., maintenance, validation task and status checks.DBCC CHECKDB - Ensures that tables in the db and the indexes are correctly linked.and DBCC CHECKALLOC To check that all pages in a db are correctly allocated. DBCC SQLPERF - It gives report on current usage of transaction log in percentage. DBCC CHECKFILEGROUP - Checks all tables file group for any damage.
Question: What is the difference between a HAVING CLAUSE and a WHERE CLAUSE?
Answer: Having Clause is basically used only with the GROUP BY function in a query. WHERE Clause is applied to each row before they are part of the GROUP BY function in a query.
Question: When do you use SQL Profiler?
Answer: SQL Profiler utility allows us to basically track Connections to the SQL Server and also determine activities such as which SQL Scripts are running, failed jobs etc.
Question: Can you explain the role of each service?
Answer: SQL SERVER - is for running the databases SQL AGENT - is for automation such as Jobs, DB Maintenance, Backups DTC - Is for linking and connecting to other SQL Servers.

Question: What is Normalization ?
Answer: The logical design of the database, including the tables and the relationships between them, is the core of an optimized relational database. A good logical database design can lay the foundation for optimal database and application performance. A poor logical database design can impair the performance of the entire system.

Normalizing a logical database design involves using formal methods to separate the data into multiple, related tables. A greater number of narrow tables (with fewer columns) is characteristic of a normalized database. A few wide tables (with more columns) is characteristic of an nonnomalized database. Reasonable normalization often improves performance. When useful indexes are available, the Microsoft® SQL Server™ 2000 query optimizer is efficient at selecting rapid, efficient joins between tables.

Some of the benefits of normalization include:
•Faster sorting and index creation.
•A larger number of clustered indexes. For more information, Narrower and more compact indexes.
•Fewer indexes per table, which improves the performance of INSERT, UPDATE, and DELETE statements.
•Fewer null values and less opportunity for inconsistency, which increase database compactness.

As normalization increases, so do the number and complexity of joins required to retrieve data. Too many complex relational joins between too many tables can hinder performance. Reasonable normalization often includes few regularly executed queries that use joins involving more than four tables.

Sometimes the logical database design is already fixed and total redesign is not feasible. Even then, however, it might be possible to normalize a large table selectively into several smaller tables. If the database is accessed through stored procedures, this schema change could take place without affecting applications. If not, it might be possible to create a view that hides the schema change from the applications.

Question: Can you tell me the difference between DELETE &TRUNCATE commands?
Answer: Delete command removes the rows from a table based on the condition that we provide with a WHERE clause. Truncate will actually remove all the rows from a table and there will be no data in the table after we run the truncate command.