SQL Server FAQs

SQL UNIQUE key... The UNIQUE constraint uniquely identifies each record in a database table. The UNIQUE and PRIMARY KEY constraints both provide a guarantee for uniqueness for a column or set of col...

If a column allows the duplication once is known as a unique key.i.e; Unique Key allows duplication once.But, Primary Key will not allow duplication. "mysql CREATE TABLE Employee (...

Self Join=It is being defined as a table joins to itself. Example as below, Imagine this Table.. E_ID E_NAME M_ID 111 SUNIL NULL 112 RAKESH 111 113 NEHA 112 114 JUHI 113 ...

joining a table to itself using alias.

select * from table_name t1
inner inner join table_name t2
on t1.x=t2.y

primary key=not allow null values,create cluster index by default.
unique key=allow only one null values and by default it create non cluster index

A Unique ID and Primary Key Constrain perform the ability to allow unique data in the column but only the Unique constrain allows NULL values in the field along with the unique data. Primary Key constrain fields allow Unique and Not NULL values.

select * from sys.tables where type = U

select * from sys.tables

Candidate Key, Alternate Key, Composite Key are also the parts of SQL Server: A candidate key is one that can identify each row of a table uniquely. Generally a candidate key becomes the primary ke...

We have different types of keys in sql:primary key      identify record uniquely     max one per table     do not contain null values &...

The fill factor simply says how large or how full to get our index pages
you can set it as 70% ,

If set to 100% it might me a bad thing if we had a lot of DML activity but if this is a read only table then
fill factor=100% is fine.

Its true, I would like to add some more information about it, Subquery take separate temp table and checking condition ………….. Besides join is checks conditions first and then put it into tabl...

I am software engineer and iam working on oracle mysql and sql so i have lot of experience on this ,basically joins are using there should be connection two or more than two tables ,joins are always o...

select DATEDIFF(MI,FromTime,ToTime) From ShiftMaster  -- between no of minutes

select starttime,stoptime,datediff(day,starttime,stoptime) as newtime from date.try this...........

SQL Server 2005 has reduced application downtime, increased scalability and performance, and tight yet flexible security controls. SQL Server 2005 makes it simpler and easier to deploy, manage, and op...

sql server 2005 is exclusively designed for dot net developers. what ever the function or procedure that we write in  dot net environment those function or procedure that  we direcly exucute in sql server environment. this is the new feature in sql 2005.

CO-RELATED Query: It used to find the exits or doesnot exits value. It has two select statement, the outer select statement will execute first and then the inner select statement execute.There is no need of relation between the two select statement.

the sub query is executed more than one time i.e,the inner query depends on outer query output is called co-related query.

  For deleting the records from the relational tables there are 4 options available. These options can be used when you create the tables then you have to use these options and create tables and ...

Use a procedure which will delete record from child table first and then it will delete the same record from parent table

Same thing can be achieved using cascade delete and cascade update, this feature was not there in sql server 7.0

sp_who2

Use SP_WHO2

sp_rename 'old_db_name','new_db_name';

Syntax of renaming the database:

sp_renamedb old_database name new_database name



Eg:  name of the database is tree. Now if you need to change the database as three. So the query for changing the database as follows:


sp_renamedb tree three

when you have to delete the records on primary key and foreigh key then there is problem will hapen as primary key violation

at that time you have to provide delete rules when you create the tables
those are

1. on delete no action
2. on delete cascade
3. on delete set null
4. on delete set default

For primary key if that record is being refered by some other (Child Table)  sql server won't let you to delete that record.While creating relationship if you had mention "Dele...

In general you put a clustered index on the key columns that you will be querying on and you can put a non clustered index on other key columns in the select statement. But you need to really look at ...

The index in the sql server are in the form of btree having root and leaf nodes.The root node contains the column key value contained in the index and the leaf node contains the table data or pointer ...

For this purpose, Views are there in SQL Server.

You can Create a view by leaving the column you need to restrict

User can edit all the fields in the view except the one you restrict .

Binita.

May be you can use Constraints.

Database mirroring maintains two copies of a single database that must reside on different server instances of SQL Server Database Engine.
Database mirroring is a primarily software solution for increasing database availability.

Commas are getting deleted here, so put commas between columns and values.

1)
insert into table (col1,col2) values (val1,val2),(val3,val4)
2)
insert into table (col1,col2)
select val1,val2
union all
select val3,val4

You can store images by BLOB (Binary Large object). Conversion should take place in front-end or SQL supports image as datatype. Try it.

Use the following steps:1) Dont use temporary tables instead use CTE or table Variable2) Use Inner Join instead of Sub Queries.3) Check indexs in tables used4) Instead of Select * from use select colu...

To expect improvemnt in stored procedure performance, pl keep following points in mind :-1. Please don't use many subqueries.2. Don't use cursor, instead of it, use temp. table in the looping....