Update Statement

UPDATE STATEMENT

Update Statement :- Update statement is used to modify existing data in Table.Update statement is a DML (Data Manipulation Language)
statement that's why  Rollback is possible for update statement.

Syntax :-  Below is the syntax for delete statement

UPDATE <Table_name> SET <column_name1>=<value1>,<column_name1>=<value1>,.. WHERE <condition>;

Note:- If "where <condition>" is not used in statement then update statement will update all records of table

1) Update all records (Without "Where" clause)Example1:- Update COURSE to 'BSC' in Student table.
SQL>UPDATE STUDENT set COURSE='BSC' ;

2) Update selected records    a) Single column updateExample2:-Update course to BSC where course is BCA
SQL>UPDATE STUDENT set COURSE='BSC' where course='BCA';
Example3:-Update course to BSC where regid is less or equal to 105
SQL>UPDATE STUDENT set COURSE='BSC' where regid<=105;

    b) multiple column update
Example4:-Update course to BSC and DOB to sysdate where course is BCA   
SQL>UPDATE STUDENT set COURSE='BSC',DOB=sysdate  where course='BCA';
Example5:-Update course to BSC and regid to regid+10 where regid less or equal to 105
SQL>UPDATE STUDENT set COURSE='BSC',regid=regid+10  where regid<=105;
  
   c) Update on one table on basis of another table
Example6:-  
SQL>UPDATE STUDENT set COURSE='BSC',DOB=sysdate  where regid in (select regno from student1);