SQL Oracle

Use of distint

• Before the 1st column name
• avoids duplicate data in column
• can not be used twice on one table

Use of q and [], ()

• words in side having

Select from dual;

• an unexisting table that can be used

Column aliases

• eg select first_name name;
• select first_name as name;
• select first_name AS name;

Concatenation using ||

• select first_name || ' ' || last_name as "full name"