The type of index you create is determined by the value of the CreateType attribute, which you set in the driver Setup dialog box (for UNIX and Linux, edit the system information file) or as a connection string attribute. The index can be:

The syntax for creating an index is:

Unique means that the driver creates an ANSI-style unique index over the column and ensures uniqueness of the keys. Use of unique indexes improves performance. ANSI-style unique indexes are different from dBASE-style unique indexes. With ANSI-style unique indexes, you receive an error message when you try to insert a duplicate value into an indexed field. With dBASE-style unique indexes, you do not see an error message when you insert a duplicate value into an indexed field. This is because only one key is inserted in the index file.

index_name is the name of the index file. For FoxPro and dBASE IV or V, this is a tag, which is required to identify the indexes in an index file. Each index for a table must have a unique name.

base_table_name is the name of the database file whose index is to be created. The .DBF extension is not required; the driver automatically adds it if it is not present. By default, dBASE IV or V index files are named base_table_name.MDX and FoxPro indexes are named base_table_name.CDX.

field_name is a name of a column in the dBASE table. You can substitute a valid dBASE-style index expression for the list of field names.

ASC tells dBASE to create the index in ascending order. DESC tells dBASE to create the index in descending order. By default, indexes are created in ascending order. You cannot specify both ASC and DESC orders within a single Create Index statement. For example, the following statement is invalid:

The following table shows the attributes of the different index files supported by the dBASE driver. For each type supported, it provides the following details: