PostgreSQL – LOCKS 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 prevents other users from changing the row until the transaction is either committed or rolled back. The […]
Category Archives: postgresql
PostgreSQL – Sub Queries 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 be used in the main query as a condition to further restrict the data to be retrieved. Subqueries can be used […]
PostgreSQL – AUTO INCREMENT 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 some other databases. If you wish a serial column to have a unique constraint or be a primary key, […]