MySQL Column Aliases

In MySQL by default the column’s heading in the results produced by your query, is the original column’s name as it was defined in the table.

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SELECT bookName FROM books   bookName ---------- The Great Gatsby Dune

In many cases, column’s heading is not descriptive enough. In addition different operations, such as: string concatenation or mathematical calculation, will change the column’s heading to be even less readable and more difficult to understand:

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SELECT CONCAT('hello', ' ' , bookName) FROM books   CONCAT('hello', ' ', bookname) ------------------------------ Hello The Great Gatsby Hello Dune

MySQL Column Aliases are used to change column’s heading. Using the MySQL Column Aliases the headings will be more easy to understand and more meaningful. To create an MySQL Column Alias use the following syntax :

1 2	SELECT column_name AS 'Column_Alias' FROM table_name

For Example : 

1 2	SELECT bookName, bookPrice, bookPrice  + 500  AS 'NewPrice' FROM books

The result:

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bookName       bookPrice     NewPrice ---------      ----------    ------------------ Dune           30            530

You can also write the MySQL column’s alias without the AS Keyword, for example:

1 2	SELECT bookName, bookPrice, bookPrice  + 500  'NewPrice' FROM books

The result:

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bookName        bookPrice   NewPrice ---------      -----------  ------------------ Dune           30           530

It is also possible to write the MySQL column’s alias without the enclosing single quotes (‘ ‘):

1 2	SELECT bookName, bookPrice, bookPrice  + 500 newPrice FROM books

The result:

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bookName        bookPrice  newPrice -----------     ---------   ------------------ Dune            30          530

• When an MySQL column alias is written without enclosing single quotes (‘ ‘), it is not possible to write the alias as two (or more) separate words; you will have to insert some character between these words, underline (_) is most commonly used in these cases.

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-- This query will generate an error -- The 'New Unit Price' column alias should be enclosed within single quotes SELECT bookName, bookPrice, bookPrice * 1.1 AS New Unit Price FROM books   -- Insert an underline between these words : SELECT bookName, bookPrice, bookPrice * 1.1 AS New_bookPrice FROM books   -- Or use single quotes : SELECT bookName, bookPrice, bookPrice * 1.1 AS 'New Unit Price' FROM books

• In order to make your MySQL query more readable, always use the AS keyword, always use single quotes (‘ ‘), and when your alias consists of two words or more, always ensure that you insert an underline between them.
• Another common approach to handle an alias consists of two words or more, is to concatenate the words, and capitalize the first letter of each word  :

1 2	SELECT bookName, bookPrice, bookPrice  + 500 AS 'NewBookPrice' FROM books