Useful SQL commands

Useful  SQL commands

Here I used Table Name as "TechConnect" for all Query.

1. To Create Table:-

> Create Table TechConnect

   (Name Varchar2(30), College_name Varchar2(30), Roll_no Number(15), D.O.B Date, Height      Number(4,2));

2. To Insert Data Into Table:-

 > Insert into TechConnect

    Values('Ram Kumar',  'ABCDE', 123001, '11-Jan-1994', 7.5);

3. To see items of table:-

 > Desc TechConnect;

4. To show whole data of a Table:-

  > Select * from TechConnect;

5. To select any Column 

  > Select Name, College_name, D.O.B from TechConnect;

6. To save :-

   

  > Commit:

7. To Delete From Table (Row / Tuple):-

  

  > Delete from TechConnect where name = 'Ram Kumar';

8. To Add extra Column in exist Table :-

  > Alter table TechConnect add (Dept Varchar2(10));

9. To delete Column:-

 > Alter table TechConnect drop Column Name;

10. To update data of a column:-

  > Update TechConnect set Dept = 'CSE' where Name = 'Ram Kumar';

11. To Change Table name:-

  > Rename TechConnect to India;

12. To Delete table (All) ;- 

  > Drop Table TechConnect;

13. To Select Tuple:- 

  > Select * from TechConnect where D.O.B = '11-June-1994';

14. To Update any Tuple :-

> Update TechConnect set  D.O.B = '10-Dec-1994' where Name = 'Ram Kumar';

15. To make Key as SUPER:-

  > Create Table TechConnect

   (Name Varchar2(30), College_name Varchar2(30), Roll_no Number(15), D.O.B Date, Height        Number(4,2), Primary Key (Name, Roll_no));

or > Create Table TechConnect

   (Name Varchar2(30) Primary Key, College_name Varchar2(30), Roll_no Number(15) Primary Key, D.O.B Date, Height  Number(4,2));

16. To Make Foreign Key :-

  > Create Table TechConnect

   (Name Varchar2(30), College_name Varchar2(30) references INDIA (College_code), Roll_no Number(15), D.O.B Date, Height  Number(4,2));

/* Above INDIA is table name and College_code is Column Name */

17. To Make / Check Conditions:-

  > Create Table TechConnect

   (Name Varchar2(30) Primary Key, College_name Varchar2(30) Check (College_name like 'AB%'), Roll_no Number(15), D.O.B Date, Height Number(4,2) check (Height > 4.7));

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