In MySQL, an alias is a temporary name assigned to a table or column in a query. Aliases can make queries more readable and can be used to rename tables or columns in a query without changing the underlying database schema.
To create an alias for a table, you can use the AS
keyword followed by the alias name:
SELECT column_name(s) FROM table_name AS alias_name WHERE condition;
In this syntax, column_name(s)
is the name of the column(s) you want to select, table_name
is the name of the table, alias_name
is the temporary name you want to assign to the table, and condition
is the condition that the data must meet to be included in the results.
Here’s an example of how you could use an alias to rename a table in a query:
SELECT * FROM customers AS c WHERE c.country = 'USA';
In this example, the AS
keyword is used to create an alias c
for the customers
table. The WHERE
clause then filters the results to only include customers from the United States.
To create an alias for a column, you can use the same syntax, but place the alias after the column name:
SELECT column_name AS alias_name FROM table_name WHERE condition;
In this syntax, column_name
is the name of the column you want to select, alias_name
is the temporary name you want to assign to the column, and condition
is the condition that the data must meet to be included in the results.
Here’s an example of how you could use an alias to rename a column in a query:
SELECT order_id, order_date AS date_ordered FROM orders WHERE customer_id = 123;
In this example, the AS
keyword is used to create an alias date_ordered
for the order_date
column. The WHERE
clause then filters the results to only include orders from a specific customer.
Note that aliases are only valid for the duration of the query and do not change the underlying database schema.