DDL Commands in Oracle SQL With Examples

• DDL stands for Data Definition Languages .
• DDL Commands Used for create and modify the structure of the Objects ,Views, Sequences,Indexes, Schemas etc.
• Data Definition Languages is one of the Sub Language. 
• the commands of the DDL Language is 

1. Create 
2. Alter
3. Truncate
4. Drop
5. Rename(Replace)

1. Create

• It is used to create the Tables, Views, Functions, Synonyms etc.
• CREATING TABLE
  
   CREATE TABLE MYSHOPSTAP
     (
      ID NUMBER PRIMARY KEY,
     WORKER_NAME VARCHAR2(20),
     DEPTNO NUMBER
       );
  
  Table created.
  
  SQL> COMMIT;
  
  Commit complete.
   SELECT * FROM MYSHOPSTAP;
  
          ID WORKER_NAME              DEPTNO                                    
  ---------- --------------------                 ---------                                    
           1 SAKHI                                   100                                    
           2 KRISH                                   101                                    
           3 KISHORE                             101                                    
           4 GOPI                                     102                                    
  .

2. Rename

• It is used to rename the Tables .
• It one of the DDL Command     

           RENAME MYSHOPSTAP TO MYSHOP;    

3. Alter

• It is used to  alter the existing  table .
• The operations happen in Column level only.
• We can Delete the Column ,We can Rename the Column, We can Modify the Column, Enable, Disable the Columns and we can add the Column.
• The Sub Commands of Alter are 1)Add, 2) Modify, 3) Drop, 4) Rename,5) Enable, 5)Disable
• The Sub Commands are apply on Records of the Tables,Views.

           ADD :

            ALTER TABLE MYSHOP

            ADD

             (

             CITY VARCHAR2(20)

             );

          MODIFY :

           ALTER TABLE MYSHOP

            ADD

             (

             CITY VARCHAR2(100)

             );

          DROP :

            ALTER TABLE MYSHOP

             DROP COLUMN CITY;

         RENAME :

             ALTER TABLE MYSHOP

             RENAME COLUMN WORKER_NAME TO NAME;

4. Truncate

• It is used to Delete all the records of the the tables Permanently but structure remains same.
•   It is one of the sub command of DDL Command.
•  Roll Back will not generate the to get  back the Data 

        TRUNCATE TABLE MYSHOP;

  5 Drop

• It is used to Delete the Table Permanently
• it is one of the Sub Language.

       DROP  TABLE MYSHOP; 

Top Searching Topics

Indexes in oracle with examples.