PostgreSQL – NULL Values The PostgreSQL NULL is the term used to represent a missing value. A NULL value in a table is a value in a field that appears to be blank. A field with a NULL value is a field with no value. It is very important to understand that a NULL value […]
Category Archives: postgresql
PostgreSQL – ALIAS Syntax You can rename a table or a column temporarily by giving another name, which is known as ALIAS. The use of table aliases means to rename a table in a particular PostgreSQL statement. Renaming is a temporary change and the actual table name does not change in the database. The column […]
PostgreSQL – TRIGGERS PostgreSQL Triggers are database callback functions, which are automatically performed/invoked when a specified database event occurs. The following are important points about PostgreSQL triggers − PostgreSQL trigger can be specified to fire Before the operation is attempted on a row (before constraints are checked and the INSERT, UPDATE or DELETE is attempted) […]