1/28/16

USING ALIASES

CREATE WITH SELECT

We can create a table using existing table [along with data].


Syntax:

Create table <new_table_name> [col1, col2, col3 ... coln] as select * from <old_table_name>;

Ex:

SQL> create table student1 as select * from student;


Creating table with your own column names.

SQL> create table student2(sno, sname, smarks) as select * from student;


Creating table with specified columns.

SQL> create table student3 as select no,name from student;


Creating table with out table data.

SQL> create table student2(sno, sname, smarks) as select * from student where 1 = 2; In the above where clause give any condition which does not satisfy.

INSERT WITH SELECT


Using this we can insert existing table data to a another table in a single trip. But the table structure should be same.

Syntax:

Insert into <table1> select * from <table2>;


Ex:

SQL> insert into student1 select * from student;


Inserting data into specified columns

SQL> insert into student1(no, name) select no, name from student;





COLUMN ALIASES


Syntax:

Select from
_name>;


Ex:

SQL> select no sno from student; or
SQL> select no “sno” from student;


TABLE ALIASES


If you are using table aliases you can use dot method to the columns.


Syntax:

Select <alias_name>.<col1>, <alias_name>.<col2> … <alias_name>.<coln> from <table_name> <alias_name>;

Ex:


SQL> select s.no, s.name from student s;

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