CODEWITHSUNDEEP
sqloracle-databaseselect
user3178424
user3178424

Reputation: 37

Second table name after FROM tables

I'm editing some views and came across something that is new to me:

SELECT rn3.create_date
FROM receipt_note rn3
WHERE rn3.receipt_num = receipt_data.receipt_num

I'm just wondering what the rn3 does in the from part of the statement?

As there isn't a comma between them showing its another table and I dont see a table or view in my database called rn3.

Upvotes: 1

Views: 132

Answers (1)

juergen d
juergen d

Reputation: 204924

It is called an Alias.

You can define another name to use in your queries. Mostly used as shorter name of tables to simplify your queries. Example:

select t.some_column
from very_long_table_name t

Or if you join the same table twice then you need aliases to distinguish between the two. Example:

select child.name, parent.name
from users child
join users parent on child.parent_id = parent.id

And as stated in comments: When using DB engines other than Oracle, you can but don't need to define the as keyword:

select t.*
from some_table_name as t

Upvotes: 4

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