fastread homefastrread library fastread menu

MariaDB : ALIASES

Tutorial by:      Date: 2016-04-18 05:10:39

❰ Previous Next ❱

This MariaDB tutorial explains how to use MariaDB ALIASES (temporary names for columns or tables) with syntax and examples.

Description

MariaDB ALIASES can be used to create a temporary name for columns or tables.

  • COLUMN ALIASES are used to make column headings in your result set easier to read.
  • TABLE ALIASES are used to shorten your SQL to make it easier to read or when you are performing a self join (ie: listing the same table more than once in the FROM clause).

Syntax

The syntax to alias a column in MariaDB is:

column_name [ AS ] alias_name

OR

The syntax to alias a table in MariaDB is:

table_name [ AS ] alias_name

Parameters or Arguments

column_name

The original name of the column that you wish to alias.

table_name

The original name of the table that you wish to alias.

AS

Optional. Whether you specify the AS keyword or not has no impact on the alias in MariaDB.

alias_name

The temporary name to assign to the column or table.

Note

  • If the alias_name contains spaces, you must enclose the alias_name in quotes.
  • It is acceptable to use spaces when you are aliasing a column name. However, it is not generally good practice to use spaces when you are aliasing a table name.
  • The alias_name is only valid within the scope of the SQL statement.
  • Most programmers will specify the AS keyword when aliasing a column name, but not when aliasing a table name.

Example - ALIAS a column

Generally, aliases are used to make the column headings in your result set easier to read in MariaDB. For example, when using the COUNT function, you might alias the result of the COUNT function.

For example:

SELECT site_name, COUNT(site_id) AS Total

FROM sites

GROUP BY site_name;

In this example, we've aliased the COUNT(site_id) field as Total. As a result, Total will display as the heading for the second column when the result set is returned. Because our alias_name did not include any spaces, we are not required to enclose the alias_name in quotes.

However, it would have been perfectly acceptable to write this example using quotes as follows:

SELECT site_name, COUNT(site_id) AS "Total"

FROM sites

GROUP BY site_name;

Next, let's look at an example where we are required to enclose the alias_name in quotes because the alias contains spaces.

For example:

SELECT site_name, COUNT(site_id) AS "Total Sites"

FROM sites

GROUP BY site_name;

In this example, we've aliased the COUNT(site_id) field as "Total Sites". Since there are spaces in this alias_name, "Total Sites" must be enclosed in quotes.

Example - ALIAS a Table

When you create an alias on a table in MariaDB, it is either because you plan to list the same table name more than once in the FROM clause (ie: self join), or you want to shorten the table name to make the SQL statement easier to read.

Let's look at an example of how to alias a table name in MariaDB

For example:

SELECT pages.page_id, s.site_name

FROM sites s

INNER JOIN pages

ON s.site_id = pages.site_id

WHERE s.site_name = 'Fastread.aitechtonic.com'

ORDER BY pages.page_id;

In this example, we've created an alias for the sites table called s. Now within this SQL statement, we can refer to the sites table as s.

When creating table aliases, it is not necessary to create aliases for all of the tables listed in the FROM clause. You can choose to create aliases on any or all of the tables.

For example, we could modify our example above and create an alias for the pages table as well.

SELECT p.page_id, s.site_name

FROM sites s

INNER JOIN pages p

ON s.site_id = p.site_id

WHERE s.site_name = 'Fastread.aitechtonic.com'

ORDER BY p.page_id;

Now we have an alias for the pages table called p as well as the alias for the sites table called s.

 

❰ Previous Next ❱


MariaDB

Submit Your Thought, Tutorial, Articls etc.

Submit Your Information India's Number one online promotion website