SQL UPDATE

SQL UPDATE 

This statement is  to modify/Update the existing records in a table.

Student table:

Regno

Name

Dob

Contact

state

1001

funda

20-june-2000

9696985457

karnataka

1002

of

18-march-2003

8585969674

haryana

1003

web

12-may-1998

8256968475

karnataka

1004

it

24-nov-1994

9785956748

goa


Syntax:

UPDATE table_Name set Column1 = value1,Column2 = value2.. WHERE Condition;

Example : 

Update student set name='om', contact='8596874858' WHERE regno=1001;

The OUTPUT for the above query:

Regno

Name

Dob

Contact

state

1001

om

20-june-2000

8596874858

karnataka

1002

of

18-march-2003

8585969674

haryana

1003

web

12-may-1998

8256968475

karnataka

1004

it

24-nov-1994

9785956748

goa


UPDATE MULTIPLE RECORDS

Here, Where clause decides how many rows or records will get updated.

Following statement will updated the name to om where state is karnataka

Example:

UPDATE student set name='om' WHERE state='Karnataka';

The OUTPUT for the above query:

Regno

Name

Dob

Contact

state

1001

om

20-june-2000

9696985457

karnataka

1002

of

18-march-2003

8585969674

haryana

1003

om

12-may-1998

8256968475

karnataka

1004

it

24-nov-1994

9785956748

goa


When you update any record, you must be careful and use the WHERE condition. If you dont use the WHERE condition all the records will get updated.

Example:

UPDATE Student SET state='karnataka';

The OUTPUT for the above query:

Regno

Name

Dob

Contact

state

1001

funda

20-june-2000

9696985457

karnataka

1002

of

18-march-2003

8585969674

karnataka

1003

web

12-may-1998

8256968475

karnataka

1004

it

24-nov-1994

9785956748

karnataka


IF you want to update a single record use Where condition.

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