SQL UNION vs UNION ALL Operator Usage
UNION:
UNION combines the result set of two or more queries into a single result set. UNION removes duplicate records (where all columns in the results are the same).
UNION...
Whenever you want data (columns) to be fetched from more than a single table then think of JOINS in SQL.It could be 2 or more tables.*Mostly you join using Primary key and Foreign Key1) if you want only...
SQL tip 1:
Instead of Full Outer Join, you can use Union All.
Difference is, Full Outer Join provides results side by side.
Union All provides result s one by one.
Note: MYSQL does not support Full...
Truncate:
Truncate command will delete the Table data only, it keeps the table schema as it is.
Table data Can be rollback
Example : TRUNCATE TABLE User;
Drop:
Drop command will delete both...
VIRTUAL OR DERIVED COLUMN
A nice feature introduced in Oracle 11gR1. Welcome to the practical analysis of various scenarios with virtual columns - introduced in 11gR1 are like normal table columns whose...