SQL UPDATE Statement

UPDATE Statement

        The UPDATE statement is used to modify the data values for particular record in the table.

Syntax:

UPDATE table_name SET column1=value, column2=value2,...
WHERE some_column=some_value

Note: ‘WHERE’ Clause in Update command to be must. That WHERE Clause specifies which record or records that should be updated. Without WHERE Clause all records of table to be modified.

Example:

        The Table “Contact” has following data,

ID	NAME	DESIGNATION	CITY	MOBILE
1	venkat	CEO	Kodambakkam	999989845
2	Santhosh	manager	Puddukottai	9999898978
3	Kousilaya	Asst.manager	Trichy	9659315754
4	Ananth	CEO	Chennai	9999999945
5	Sajil	MD	Surandai	6677888997

If we want to change designation of employee “Ananth” as Developer and mobile-9698958775, we use following syntax,

UPDATE contact SET Designation=’Developer’, Mobile=9698958775 WHERE Name=’Ananth’

The Result-Set is,

ID	NAME	DESIGNATION	CITY	MOBILE
1	venkat	CEO	Kodambakkam	999989845
2	Santhosh	manager	Puddukottai	9999898978
3	Kousilaya	Asst.manager	Trichy	9659315754
4	Ananth	Developer	Chennai	9698958775
5	Sajil	MD	Surandai	6677888997

Note: SQL Not Case-Sensitive and Varchar datatype should be enclosed with single quote.

If we omit the WHERE Clause in the above command like,

UPDATE contact SET Designation=’Developer’, Mobile=9698958775

The Result-set is,

ID	NAME	DESIGNATION	CITY	MOBILE
1	venkat	Developer	Kodambakkam	9698958775
2	Santhosh	Developer	Puddukottai	9698958775
3	Kousilaya	Developer	Trichy	9698958775
4	Ananth	Developer	Chennai	9698958775
5	Sajil	Developer	Surandai	9698958775