When you run a query for displaying the result of a query, a column aliases is useful rename that columns with calculations, so you can change easily column header using a column aliases. Always define a column alias after the column name, by default column alias header appear in uppercase, if you use space or special characters or it’s case-sensitive so alias close in double quotation(” “) marks.
We have three ways to define column aliases
1. Using below query we can define column alias.
SQL> select first_name name from ocp;
2. You can also define alias name with “as” keyword. Use below query for example.
SQL> select salary as sal from ocp;
3. If you want to define two word name, then use alias name in double quot “”, below query will show you Annual Salary as name of salary column.
SQL> select salary*12 "Annual Salary" from ocp;
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