SQL Tables: -
After learning types of SQLstatements in my last post, Now we will learn about SQL Tables,
Table is a database object which holds the data and contains one or more
columns
associated with its datatypes
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| Table Structure |
Creating
a Table: we use the create table statement to create a table. The simple
syntax
for the creation of table.
Syntax:
CREATE Table table_name
(column_name
type [CONSTRAINT constraint_def DEFAULT default_exp],
column_name
type [CONSTRAINT constraint_def DEFAULT default_exp],
column_name
type [CONSTRAINT constraint_def DEFAULT default_exp]…
)
[ON
COMMIT {DELETE | PRESERVE} ROWS]
TABLESPACE
tab_space;
Ex:
SQL> Create table chaitu_0016(ename varchar2(10),
Eno
number unique);
Table
Created.
Altering
a Table: we can alter the table using the alter statement. The alter table
statement
perform such tasks given below.
_
Add, modify, or drop a column.
_
Add or drop a constraint.
_
Enable or Disable a constraint.
Ex:
SQL> Alter table chaitu_0016
Add
address varchar2(10);
Modifying
a Column:
Ex:
SQL> Alter table chaitu_0016
Modify
address varchar2(20);
Dropping
a Column:
Ex:
SQL> Alter table chaitu_0016
Drop
address;
Renaming
a Table: If we want to change the name of the table then we use this
RENAME
statement.
Ex:
SQL> Rename table chaitu_0016
To
Chaitu_0015;
Truncating
a Table: If we want to delete all the rows existing in the table then we use
the
TRUNCATE Statement.
Ex:
SQL> Truncate table chaitu_0015;
Dropping
a Table: If we want to drop the total structure along with the records existing
in
the table we use this DROP statement.
Ex:
SQL> Drop table chaitu_0015;
Thanks
a lot for reading.. Happy Blogging!
