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Monday, 28 March 2016

SQL DML Operations

USING  INSERT

This will be used to insert the records into table.We have two methods to insert.
  • By value method
  • By address method

a) USING VALUE METHOD

   
     Syntax:
          insert into <table_name) values (value1, value2, value3 …. Valuen);

   
     Ex:
            SQL> insert into student values (1, ’sudha’, 100);
            SQL> insert into student values (2, ’saketh’, 200);
         
     To insert a new record again you have to type entire insert command,
        if there are lot of  records this will be difficult.
     This will be avoided by using address method.

b) USING ADDRESS METHOD

   
      Syntax:
          insert into <table_name) values (&col1, &col2, &col3 …. &coln);

     This will prompt you for the values but for every insert you have to use forward        slash.
    
      Ex:
            SQL> insert into student values (&no, '&name', &marks);

Enter value for no: 1
Enter value for name: Jagan
Enter value for marks: 300
old   1: insert into student values(&no, '&name', &marks)
new   1: insert into student values(1, 'Jagan', 300)

SQL> /
Enter value for no: 2
Enter value for name: Naren
Enter value for marks: 400
old   1: insert into student values(&no, '&name', &marks)
new   1: insert into student values(2, 'Naren', 400)

c) INSERTING DATA INTO SPECIFIED COLUMNS USING VALUE METHOD

   
     Syntax:
           insert into <table_name)(col1, col2, col3 … Coln) values (value1, value2, value3 ….Valuen);

     Ex:
            SQL> insert into student (no, name) values (3, ’Ramesh’);
            SQL> insert into student (no, name) values (4, ’Madhu’);

d) INSERTING DATA INTO SPECIFIED COLUMNS USING ADDRESS METHOD

   
     Syntax:
          insert into <table_name)(col1, col2, col3 … coln) values (&col1, &col2, &col3 …. &coln);

     This will prompt you for the values but for every insert you have to use forward slash.
    
     Ex:
            SQL> insert into student (no, name) values (&no, '&name');
Enter value for no: 5
Enter value for name: Visu
old   1:  insert into student (no, name) values(&no, '&name')
new   1:  insert into student (no, name) values(5, 'Visu')

SQL> /
Enter value for no: 6
Enter value for name: Rattu
old   1:  insert into student (no, name) values(&no, '&name')
new   1:  insert into student (no, name) values(6, 'Rattu')

USING UPDATE


This can be used to modify the table data.

Syntax:
     Update <table_name> set <col1> = value1, <col2> = value2 where <condition>;

Ex:
     SQL> update student set marks = 500;
     If you are not specifying any condition this will update entire table.

     SQL> update student set marks = 500 where no = 2;
     SQL> update student set marks = 500, name = 'Venu' where no = 1;

USING DELETE


This can be used to delete the table data temporarily.

Syntax:
    Delete <table_name> where <condition>;

Ex:
     SQL> delete student;
     If you are not specifying any condition this will delete entire table.

     SQL> delete student where no = 2;
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