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This section provides a detailed description of the user interface elements and common tasks of the Table designer.

To open the Table designer to modify an existing table, right-click the table on the Tables page of the Navigator, and choose Design Table from the context menu, or select the table and click the Table Design button in the toolbar.

The Table designer lists the fields defined in the table, along with the attributes for each field.

Field contains a number that identifies the field in the table. Field numbers are consecutive, automatic, and read-only. They determine the default order in which fields appear in the Table window.

Name is the name of the field (up to 31 characters for dBASE Plus). You can enter letters, numbers, and underscores, but no other characters. The first character must be a letter. While the table designer may allow spaces to be entered, not all table types allow spaces in field names. dBASE Level 3, 4, and 5 tables do not allow spaces in field names. Level 7 tables permit spaces in field names. Paradox and many SQL tables also allow spaces.

Type is the field type. Select the type you want from the list. The type you select determines what kind of data the field will contain. It also determines whether you can set the width, decimals, and index options for this field.

Width is the field size. In the case of dBASE tables you can change field size for character, numeric, and float fields only (all others have fixed width). Never use functions that vary field widths.

Decimal is the number of digits allowed to the right of the decimal point (for float and numeric fields only). In the case of dBASE tables, float and numeric fields, by default, have no decimals selected. You can set decimals to a maximum of 2 less than the width value you define. The total width must be 20 characters or less. This includes decimal settings, the decimal point, and an optional minus sign.

Index determines whether to index rows using the values in this field (you can set an index on character, date, float, and numeric fields in dBASE tables). Select Ascend to index this field in ascending order (for character fields, this is ASCII order, or the order determined by your language driver). Selecting Descend indexes this field in descending order, and None (the default) omits this field from indexing (or removes an existing index associated with this field).

If you select Ascend or Descend for a dBASE table, the Table designer creates an index for the field in the multiple index file (.MDX) associated with the table.

To set a primary key on a dBASE 7 or Paradox table, choose Structure|Define Primary Key. Some SQL types also support this.

You can also set other field attributes or create custom field attributes by selecting the field and right-clicking the Inspector.