OraclePLSQL-Page4

-

                                                                            

👉Alter table Command

The structure of a table can be modified using the ALTER command.

Alter table works by making a temporary copy of the original table, the alteration is performed on the copy, then the original table is deleted and the new one is renamed.

👉Renaming Tables

👉Truncating Tables

Truncate table empties a table completely.
Truncate operations drop and re-create the table, which is much faster than deleting rows one by one.

👉Destroying Tables

Drop table statement with the table name can destroy a specific table.


Comments

Post a Comment

Popular posts from this blog

SQL-ForeignKeyConstraint-Page6

-
Image
                                                                              👉 Foreign Key Constraint Foreign Key represent relationships between tables. A foreign key is a column or group of columns whose values are derived from the primary key or unique key of some other table. ✅ The table in which the foreign key is defined is called Foreign table or Detail table. ✅ The table that defines the primary or unique key and is referenced by the foreign key is called the Primary table or Master table. 👉 Features 1)Master table cannot be updated if child records exists. 2)Records cannot be inserted or deleted into a detail table if corresponding records in the master table do not exist. 3)Records of the master table cannot be deleted if corresponding records in the detail table already exist. 👉 O...
Read more

Javascript-OOPs(Part3)-Inheritance - (9)

-
Image
   👉 Javascript with OOPs (Inheritance) In Javascript, Inheritance is done using prototype object. A prototype object is an object pointing to another object. We don't have a direct inheritance in Javascript, we can mimic inheritance using prototype. Let's say, we have one more class that inherits from Customer, and it submits to Server2. function CustomerChild(){         this.submit = function() {         alert ("this submits the data to Server2" + " "      +  this.CustomerName + " "                                       + this.CustomerCode");   }}             CustomerChild.prototype = new Customer(); var cust = new Customer(); cust.CustomerName ("John"); cust.Submit();  --this is a call to the submit method of the Customer class.  cust = new CustomerChild(); cust...
Read more

OraclePLSQL-Page3

-
Image
                                                                                          👉 Creating a table from a table Below SQL syntax populates the target table with data from the source table. To create a target table without the records from the source table, the SELECT statement must have a WHERE clause. The WHERE clause must specify a condition that cannot be specified. 👉 Inserting data into a table from another table It is used to populate a table with data that already exist in another table. 👉DELETE Command The DELETE command deletes the rows from the table that satisfies the condition and returns the number of records deleted.
Read more