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SQL Clause


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SQL Clause

In SQL there are many clauses which are widely used in SQL database. In SQL server mainly two clauses are widely used namely: WHERE and TOP. Let’s see these two descriptions briefly.

SQL WHERE Clause:

The WHERE clause is used to extract only those records that fulfill specified criterion. The WHERE clause allows you to filter the results from an SQL statement - Select, Update, or Delete statement.

Example: Using WHERE clause

--- select data field from STUDENT_DETAIL table where  condition are true

 select * from STUDENT_DETAIL where id = 102 

Desired Output:

102         VARUN SINGH

SQL TOP Clause:

The TOP clause is used to specify the number of records to return. The TOP clause can be very useful on large tables with thousands of records. Returning a large number of records can impact on performance.

The "TOP" clause will now allow us to do Data Manipulation and also allow similar criteria results to be displayed by using the TIES option.

Example: Using TOP Clause

--- select top 3 data field from STUDENT_DETAIL

 select top(3)* from STUDENT_DETAIL 

//with condition

--- select top 3 data field from STUDENT_DETAIL

 select top(3)* from STUDENT_DETAIL where id = 102 

--- update top 3 data field from STUDENT_DETAIL where condition is true

update top(3) STUDENT_DETAIL set name = 'kajal' where id = 102 


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