PostgreSQL - Object Relation Database

PostgreSQL - Object Relational Database from Mubashar Iqbal

SQL UNION Operator

SQL UNION Operator

The UNION operator is used to combine the result-set of two or more SELECT statements.

SELECT column_name(s) FROM table1
UNION
SELECT column_name(s) FROM table2;

SQL RIGHT JOIN

SQL RIGHT JOIN

The RIGHT JOIN keyword returns all rows from the right table (table2), with the matching rows in the left table (table1). The result is NULL in the left side whenthere is no match.

SELECT column_name(s)
FROM table1
RIGHT JOIN table2
ON table1.column_name=table2.column_name;

SQL LEFT JOIN

SQL LEFT JOIN

The LEFT JOIN keyword returns all rows from the left table (table1), with the matching rows in the right table (table2). The result is NULL in the right side whenthere is no match.

SELECT column_name(s)
FROM table1
LEFT JOIN table2

ON table1.column_name=table2.column_name;

PDO vs MYSQLI

PDO MySQLi

Database support 12 different drivers MySQL only
API OOP OOP + procedural
Connection Easy Easy
Named parameters Yes No
Object mapping Yes Yes
Prepared statements
(client side) Yes No
Performance Fast Fast
Stored procedures Yes Yes

Database Support

PDO:

CUBIRD, mysql server, firebird/interbase, ibm, informix, mysql, oracle, odbc, db2, postgresql, sqlite, 4d

mysqli:

mysql