MySQL naming conventions, should field name include the table name?

Question

A friend told me that I should include the table name in the field name of the same table, and I\'m wondering why? And should it be like this? Example:

(Table)         


        

Answer 1

I agree with you. The only place I am tempted to put the table name or a shortened form of it is on primary and foreign keys or if the "natural" name is a keyword.

Users: id or user_id, username, password, last_login_time
Post: id or post_id, user_id, post_date, content

I generally use 'id' as the primary key field name but in this case I think user_id and post_id are perfectly OK too. Note that the post date was called 'post_date" because 'date' is a keyword.

At least that's my convention. Your mileage may vary.

Answer 2

I see no reason to include the table name, it's superfluous. In the queries you can refer to the fields as <table name>.<field name> anyway (eg. "user.id").

Answer 3

We should define primary keys with prefix of tablename.

We should use use_id instead if id and post_id instead of just id.

Benefits:-

1) Easily Readable

2) Easily differentiate in join queries. We can minimize the use of alias in query.

user table : user_id(PK)

post table : post_id(PK) user_id(FK) here user table PK and post table FK are same

As per documentation,

3) This way we can get benefit of NATURAL JOIN and JOIN with USING

Natural joins and joins with USING, including outer join variants, are processed according to the SQL:2003 standard. The goal was to align the syntax and semantics of MySQL with respect to NATURAL JOIN and JOIN ... USING according to SQL:2003. However, these changes in join processing can result in different output columns for some joins. Also, some queries that appeared to work correctly in older versions (prior to 5.0.12) must be rewritten to comply with the standard.

These changes have five main aspects:

1) The way that MySQL determines the result columns of NATURAL or USING join operations (and thus the result of the entire FROM clause).

2) Expansion of SELECT * and SELECT tbl_name.* into a list of selected columns.

3) Resolution of column names in NATURAL or USING joins.

4) Transformation of NATURAL or USING joins into JOIN ... ON.

5) Resolution of column names in the ON condition of a JOIN ... ON.

Examples:-

SELECT * FROM user NATURAL LEFT JOIN post;
SELECT * FROM user NATURAL JOIN post;
SELECT * FROM user JOIN post USING (user_id);

Answer 4

Actually, there is a reason for that kind of naming, especially when it comes to fields, you're likely to join on. In MySQL at least, you can use the USING keyword instead of ON, then users u JOIN posts p ON p.user_id = u.id becomes users u JOIN posts p USING(user_id) which is cleaner IMO.

Regarding other types of fields, you may benefit when selecting *, because you wouldn't have to specify the list of the fields you need and stay sure of which field comes from which table. But generally the usage SELECT * is discouraged on performance and mainenance grounds, so I consider prefixing such fields with table name a bad practice, although it may differ from application to application.

Answer 5

Sounds like the conclusion is: If the field name is unique across tables - prefix with table name. If the field name has the potential to be duplicated in other tables, name it unique.

I found field names such as "img, address, phone, year" since different tables may include different images, addresses, phone numbers, and years.

Answer 6

Personally I don't add table names for field names in the main table but when using it as a foreign field in another table, I will prefix it with the name of the source table. e.g. The id field on the users table will be called id, but on the comments table it, where comments are linked to the user who posted them, it will be user_id.

This I picked up from CakePHP's naming scheme and I think it's pretty neat.