Author: S J

We had discussed about the Date/Time data types in the chapter Data Types. Now, let us see the Date/Time operators and Functions. The following table lists the behaviors of the basic…

Whenever an object is created in a database, an owner is assigned to it. The owner is usually the one who executed the creation statement. For most kinds of objects,…

PostgreSQL has the data types smallserial, serial and bigserial; these are not true types, but merely a notational convenience for creating unique identifier columns. These are similar to AUTO_INCREMENT property supported by…

A subquery or Inner query or Nested query is a query within another PostgreSQL query and embedded within the WHERE clause. A subquery is used to return data that will…

Locks or Exclusive Locks or Write Locks prevent users from modifying a row or an entire table. Rows modified by UPDATE and DELETE are then exclusively locked automatically for the duration of the transaction. This…

A transaction is a unit of work that is performed against a database. Transactions are units or sequences of work accomplished in a logical order, whether in a manual fashion…

Views are pseudo-tables. That is, they are not real tables; nevertheless appear as ordinary tables to SELECT. A view can represent a subset of a real table, selecting certain columns…

The PostgreSQL TRUNCATE TABLE command is used to delete complete data from an existing table. You can also use DROP TABLE command to delete complete table but it would remove complete table…

The PostgreSQL ALTER TABLE command is used to add, delete or modify columns in an existing table. You would also use ALTER TABLE command to add and drop various constraints on an…

Indexes are special lookup tables that the database search engine can use to speed up data retrieval. Simply put, an index is a pointer to data in a table. An…