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Тип документу: Реферат
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Предмет: Іншомовні роботи
Автор: Олексій
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The comma is not truly a delimiter.  However, the DELIMITED WITH BLANK or DELIMITED WITH TAB clauses allow you to replace the comma field separator with either a space or a tab.  The data should not contain embedded spaces or tabs.

You cannot combine the WITH clause with either the WITH BLANK or WITH TAB clauses.

Unless you specify otherwise, a .TXT extension is assigned to all newly created DELIMITED files.

The format of APPEND is:

APPEND FROM | ?

   [FIELDS ]

   [FOR ]

   [[TYPE]           [DELIMITED [WITH TAB | WITH | WITH BLANK] |

DIF | FW2 | MOD | PDOX | RPD | SDF | SYLK | WK1 | WK3 | WKS |

WR1 | WRK | XLS]]

Remarks

The file you are appending from is assumed to be a FoxPro table with a .DBF extension.  If the file you want to append from is a FoxPro table and doesn't have a .DBF extension, you must specify its extension.  If the file is a not a FoxPro table, you must specify the type of file you append from. 

Before you can append from a table created in dBASE IV that contains a memo field, you must first open the table in FoxPro with USE.  You are prompted with "Convert MEMO file to FoxPro Format?"  Choose Yes.

If you append from a FoxPro table, the table you append from can be open in another work area.  You can also append from a table that isn't open but is available on disk and a shared table opened when SET EXCLUSIVE is OFF.  When the table you append from contains records marked for deletion, the records are not marked for deletion after they are appended.

If you include the ? clause instead of including a table name, the Open dialog appears so you can choose a table to append from.

Clauses

Specify the name of the file to append from with .  If you don't include a file name extension, the default extension .DBF is assumed.

FIELDS

APPEND FROM supports an optional .  Data is only appended to the fields specified in the field list.

FOR

The entire source file is appended to the table unless you include the FOR clause.  If the FOR clause is included, a new record is appended for each record in the file source for which evaluates to a logical true (.T.).  Records are appended until the end of the file is reached. 

TYPE

If the file you are appending from isn't a FoxPro table, you must specify the file TYPE.  Although you must specify the file type, you need not include the key word TYPE.  You can append from a wide variety of different file types including DELIMITED ASCII text files in which you can specify a field delimiter.

If the file you are appending from doesn't have the usual default file extension for that type of file, the source file name must include the file's extension.  For example, Microsoft Excel spreadsheets normally have an .XLS file name extension.  If the spreadsheet you are appending from has an extension other than the expected .XLS, be sure to specify the extension.

Caution   When appending from a spreadsheet, the data in the spreadsheet must be stored in a row major order rather than a column major order.  This allows the appended spreadsheet data to match the table structure.

DELIMITED [WITH TAB | WITH | WITH BLANK]

A DELIMITED file is an ASCII text file in which each record ends with a carriage return and line feed.  Field contents are by default assumed to be separated from each other by commas, and character field values to be additionally delimited by double quotation marks.  For example:

"Smith", 9999999, "TELEPHONE"

The DELIMITED WITH TAB option can be used to specify files which contain fields separated from each other by tabs rather than commas.  The DELIMITED WITH option can be used to indicate that character fields are delimited by a character other than the quotation mark.  The DELIMITED WITH BLANK option can be used to specify files which contain fields separated by spaces instead of commas.  The file extension is assumed to be .TXT for all delimited files.

You can import dates from delimited files if the dates are in proper date format.  The date format defaults to 'mm/dd/yy'.  Including the century portion of a date is optional. FoxPro will import a date that includes the century.  If the century isn't included in a date (for example '12/25/92'), the Twentieth century is assumed.  Date delimiters can be any non-numeric character except the delimiter that separates the fields in the delimited file.

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