List of standard lengths for database fields

databasestandards

I'm designing a database table and once again asking myself the same stupid question: How long should the firstname field be?

Does anyone have a list of reasonable lengths for the most common fields, such as first name, last name, and email address?

Best Answer

I just queried my database with millions of customers in the USA.

The maximum first name length was 46. I go with 50. (Of course, only 500 of those were over 25, and they were all cases where data imports resulted in extra junk winding up in that field.)
Last name was similar to first name.
Email addresses maxed out at 62 characters. Most of the longer ones were actually lists of email addresses separated by semicolons.
Street address maxes out at 95 characters. The long ones were all valid.
Max city length was 35.

This should be a decent statistical spread for people in the US. If you have localization to consider, the numbers could vary significantly.

Related Solutions

Mysql – How to quickly rename a MySQL database (change schema name)

For InnoDB, the following seems to work: create the new empty database, then rename each table in turn into the new database:

RENAME TABLE old_db.table TO new_db.table;

You will need to adjust the permissions after that.

For scripting in a shell, you can use either of the following:

mysql -u username -ppassword old_db -sNe 'show tables' | while read table; \ 
    do mysql -u username -ppassword -sNe "rename table old_db.$table to new_db.$table"; done

for table in `mysql -u root -ppassword -s -N -e "use old_db;show tables from old_db;"`; do mysql -u root -ppassword -s -N -e "use old_db;rename table old_db.$table to new_db.$table;"; done;

Notes:

There is no space between the option -p and the password. If your database has no password, remove the -u username -ppassword part.
If some table has a trigger, it cannot be moved to another database using above method (will result Trigger in wrong schema error). If that is the case, use a traditional way to clone a database and then drop the old one:

mysqldump old_db | mysql new_db
If you have stored procedures, you can copy them afterwards:

mysqldump -R old_db | mysql new_db

Sql – How to list the tables in a SQLite database file that was opened with ATTACH

There are a few steps to see the tables in an SQLite database:

List the tables in your database:
```
.tables
```
List how the table looks:
```
.schema tablename
```
Print the entire table:
```
SELECT * FROM tablename;
```
List all of the available SQLite prompt commands:
```
.help
```

Best Answer

Related Solutions

Mysql – How to quickly rename a MySQL database (change schema name)

Sql – How to list the tables in a SQLite database file that was opened with ATTACH

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