Use of Long Names

ID: Q129866

3.00 WINDOWS kbprg

The information in this article applies to:

Microsoft Visual FoxPro for Windows, version 3.0

SUMMARY

Visual FoxPro for Windows allows long names for tables and fields within a database. Names of up to 128 characters are allowed.

MORE INFORMATION

The long name for the table is not the actual file name as displayed in file manager but an additional name for the table stored in the database container. So there are two table names, and you can use either one to open the table when the database is opened. However, there is only one field name per field.

The DISPLAY TABLES command lists the long table names and their actual file names. Use ADBOBJECT(arrayname,'table') to put the table names into an array. The array will contain only one name per table. If a table does not have a long name, the array will contain its filename. Filenames are only eight characters under Windows and Windows for Workgroups. In operating systems such as Windows NT, the actual file names can be longer than eight characters.

The Visual FoxPro Help File lists the following rules for names:

1. Names can only contain letters, underscores, and numbers.

2. Names must begin with a character or an underscore.

3. Names can have up to 254 characters

4. Avoid use of reserved words.

Long names for fields and tables do not necessarily follow these rules. Long table names can contain spaces but long field names cannot. The following creates a table named "Long table name."

   OPEN DATABASE SYS(2004)+"samples\data\testdata.dbc"
   CREATE TABLE longname NAME "Long table name" (longfieldname c(20))

NOTE: The USE "long table name" command opens the table, but the name is displayed with underscores instead of spaces in the View Window and in SELECT commands, which require underscores instead of spaces.

Names of tables and fields abide by Rule 2. Rule 3 applies to variable names but not to long table and field names, which can be no longer than 128 characters. This is documented in the help file under the "long table names" and "fields, naming" topics.

When copying a table with a long table name and long field names, the long table name is dropped and long field names are truncated to 10 characters. If the first 10 characters of two fields are identical the second field will be truncated to nine characters and the number 2 will be added at the end. The long names are dropped or truncated because the COPY TO command does not place the new table in the database, and long names are only allowed when a table is part of a database.

The following copies the table that was created above:

   COPY TO newtable

No long table name exists because newtable is not part of the database, and the longfieldname field is truncated to "longfieldn.

REFERENCES

NOTE: For more information about the RENAME TABLE command that allows changes to be made to the long name of a table, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q129098
   TITLE     : How to Change a Table's Name

Also see the "Microsoft Visual FoxPro Developer's Guide," chapter 7, "Naming a Table" and "Naming Fields" sections.

Additional reference words: 3.00 VFoxWin KBCategory: kbprg KBSubcategory: FxotherGeneral

Keywords          : FxotherGeneral 
Version           : 3.00
Platform          : WINDOWS