USE

Topic group Related topics Example

Opens the specified table and its associated index and memo files, if any.

Syntax

USE
[<filename1> [[TYPE] PARADOX | DBASE]
[IN <alias>]
[INDEX <filename2> [, <filename3> ...]]
[ORDER [TAG] <.ndx filename> |
  <tag name> [OF <.mdx filename>]]
[AGAIN]
[ALIAS <alias name>]
[AUTOMEM]
[EXCLUSIVE | SHARED]
[NOSAVE]
[NOUPDATE]]

<filename 1>

The table you want to open.

[TYPE] PARADOX | DBASE

Specifies the type of table you want to open, if <filename> does not include an extension. This option overrides the current SET DBTYPE setting. The TYPE keyword is included for readability only; it has no effect on the operation of the command.

IN <alias>

The work area in which to open the table. You can specify the work area that is being used by another table, in which case the other table is closed first.

INDEX <filename2> [, <filename3> ...]

Applicable to DBF indexes only. (Indexes on other table types are specified by the ORDER clause.) Opens up to 100 individual index files for the specified table, which can include single (.NDX) and multiple index file (.MDX) names and wildcards.

ORDER [TAG] <tag name>

Makes the <tag name> index file the master index.

If you don't include the ORDER clause and the first file name after INDEX is a single index .NDX file, the single index file is the master index. If you don't include ORDER and the first file name after INDEX is a multiple index .MDX file, the table is in natural order. If the table has a primary key index, it is used; otherwise the table is unordered.

OF <.mdx filename>

The .MDX file that includes <tag name>. Without OF <filename>, dBASE Plus searches for <tag name> in the table’s production .MDX file, the .MDX file with the same root name as the table.

ORDER [TAG] <.ndx filename>

Makes the single index file, <.ndx filename>, the master index. The .NDX file must be specified in the INDEX clause. Use the name of the index without the file extension.

AGAIN

Opens a table and its related index files in the current or specified work area, leaving the table open in one or more other work areas. This keyword is superfluous and included for compatibility. dBASE Plus always opens tables with AGAIN.

ALIAS <alias name>

An alternate alias name to assign to the table.

AUTOMEM

Initializes a memory variable for each field of the specified table (not including memo, binary, or OLE types). The memory variables are assigned the same names and types as the fields.

EXCLUSIVE | SHARED

EXCLUSIVE opens the table so that no other users can open the table until you close it; SHARED allows other users access while the table is opened. This option overrides the current setting of SET EXCLUSIVE.

NOSAVE

Used to open a table as a temporary table. When you close a table opened with NOSAVE, it is erased along with its associated index and memo files. If you inadvertently open a table with the NOSAVE option, use COPY to save the data.

NOUPDATE

Prevents users from altering, deleting, or recalling any records in the table.

Description

The USE command opens an existing table and its associated files, including index and memo files. You need to open a table before you can access any data stored in the table.

USE with no options closes the open table and its associated files in the current work area. USE IN <alias>, with no other options, does the same in the specified work area. CLOSE TABLES closes tables in all work areas.

You can open a table in any work area. It is common practice to USE IN SELECT( ) to open the table in the first available work area. If a table is already opened in the specified work area, that table is closed before the specified table is opened.

USE...INDEX specifies index files that are opened and maintained for a particular table. For a DBF table, its production .MDX is automatically opened and does not need to be listed.

The ORDER option specifies the master index from the list of indexes opened with the INDEX option and the production .MDX index. USE...INDEX is identical to USE followed by SET INDEX. See the SET INDEX and SET ORDER commands for an explanation of the open index order and specifying a master index.

You can include .NDX as well as .MDX index file names with the INDEX option. If a table has an .NDX and an .MDX index file with the same name, dBASE Plus opens indexes listed in the .MDX index file. In that case, to open the .NDX file you would need to specify its full name, including its extension.

When opening a table, you can name the work area by including the ALIAS option in the USE command line. ALIAS names follow the same rules as file names. Aliases are used when referring to a table from another work area. If you do not specify an <alias name> the table name (without the extension) is used, unless that name is invalid, because:

That alias name is already in use by another open table, perhaps because the table is already open in another work area, or

The table name is not a valid alias name because it is a single letter from A to J or M, which are all reserved alias names, or some other reason.

If the table name is not a valid alias, a valid default alias is generated.

The AUTOMEM option creates blank automem variables for the table, as if the CLEAR AUTOMEM command was executed immediately after opening the table.

Use the NOSAVE option of USE to open a table as a temporary file. dBASE Plus automatically erases the table, along with its associated memo and index files, when you close the table.

To open a table read-only, which prevents intentional or accidental changes, use the NOUPDATE option.

OODML

Use a Query object with "SELECT * FROM <table>" as the sql property.