OS/2 Shareware BBS: 8 Other/08-Other.zip/odbcpa22.zip/IBTXT08.HLP

OS/2 Help File | 1998-04-20 | 10KB | 250 lines

ΓòÉΓòÉΓòÉ 1. Configuring a Text Data Source ΓòÉΓòÉΓòÉ

Data Source Name:
          A string that identifies this Text data source configuration in
          ODBC.INI.  Examples include "Accounting" or "Text Files."

Description:
          An optional long description of a data source name. For example, "My
          Accounting Files" or "My Text Files in the Accounting Directory."

Database Directory:
          The directory in which the text files are stored.  If none is
          specified, the current working directory is used.

The following values are optional:

Rows to Scan:
          The number of rows in a text file that the driver scans to determine
          the data types in the file.  If the value is 0, all rows in the file
          are scanned.  The default is 25.

Default Table Type:
          The type of text file:  comma-separated, tab-separated,
          character-separated, or fixed length.  This value tells the driver
          the default type, which is used when creating a new table and opening
          an undefined table.

Delimiter Character:
          The character used as a delimiter for character-separated files.  It
          can be any printable character.  The default is a comma (,).

Action for Undefined Tables:
          Two radio buttons that indicate what action the driver should take
          when it encounters a file that has not been defined.  Set the Prompt
          for Definition radio button, if you want the driver to prompt the
          user when it encounters a file whose format is not defined.
          Otherwise, set the Guess Definition radio button; in this case, the
          driver guesses the file's format.

Return Additional Tables:
          Select this check box to tell the driver to return files you have
          defined in functions like SQLTables, SQLColumns, etc.  and files with
          a given extension.  In Extension List, specify a comma-separated list
          of the extensions.  To have files with no extensions returned,
          specify NONE.  For example, if some of your files have the extensions
          TXT and CSV and others have no extension, specify TXT,CSV,NONE.

          By default, when an application requests a list of tables, only files
          that have been defined are returned.

File Open Cache:
          A numeric value to specify the maximum number of unused file opens to
          cache.  For example, the value 4 specifies that when a user opens and
          closes four tables, the tables are not actually closed.  The driver
          keeps them open so that if another query uses one of these tables,
          the driver does not have to perform another open, which is expensive.
          The advantage of file open caching is increased performance.  The
          disadvantage is that a user who specifies file locking on open may
          get a locking conflict even though no one appears to have the file
          open.  The default is 0, which means no file open caching.

Cache Size:
          The amount of memory, in 64K blocks, that the driver uses to cache
          database records.  The higher the number, the better the performance.
          The maximum number you can set depends on the system memory
          available.  This value must be a multiple of 64.  The default is
          256K.  If the cache size is greater than 0, when browsing backwards,
          you will not be able to see updates made by other users until you
          reexecute the Select statement.

Column Names in First Line:
          Select this check box to tell the driver to look for column names in
          the first line of the file.

International Sort:
          A setting to indicate the order in which records are retrieved when
          you issue a Select statement with an Order By clause.  Select this
          check box to use the international sort order as defined by your
          operating system.  International sort order is case-insensitive (a
          precedes B); the sorting of accented characters is also affected (see
          your operating system documentation).  Leave this box blank to use
          the ASCII sort order.  ASCII sort order is case-sensitive, where
          uppercase letter precede lowercase letters (B precedes a).

Note:
          The Rows to Scan, Default Table Type, Delimiter Character, and Column
          Names in First Line settings apply only to tables not previously
          defined.  These fields also determine the attributes of new tables
          created with the Create Table statement.

Use Long Qualifiers:
          A setting that enables the driver to use long pathnames as table
          qualifiers. When you set this check box, pathnames can be up to 255
          characters. The default length for pathnames is 128 characters.

Translate

Displays the Select Translator dialog box to allow you to perform  a
translation of your data from one character set to another. Choose the
INTERSOLV OEM ANSI translator to translate your data from the IBM PC character
set to the ANSI character set.


ΓòÉΓòÉΓòÉ 2. Defining Table Structure ΓòÉΓòÉΓòÉ

Since text files do not all have the same structure, the driver provides the
option of defining the structure of an existing file. Although defining the
structure is not mandatory, since the driver can attempt to guess the names and
types of the columns, this feature is extremely useful.

In this dialog box, the Database Name field and the File field are
informational fields only. The Database Name field displays the name of the
database directory that contains the file. The File field displays the name of
the file you previously selected.

Specifying Table Information

In the Table Information section of this dialog box, specify information about
the overall structure of the file:

 1. In the Table field, enter a table name. Values may be up to 32 characters
    in length and may not be the same as another defined table in the database.
    This name is returned by SQLTables. By default, it is the filename without
    its extension.

 2. Select the Column Names in First Line check box if the first line of the
    file contains column names. Otherwise, do not select this check box.

 3. Open the Table Type box and select a table type: comma, tab, fixed, or
    character.

 4. If the table type you select is character-separated, enter the character
    that separates the values in the Delimiter Character field.

 5. Select the OEM to ANSI Translation check box to tell the driver that the
    data is stored in the IBM PC character set. If your data is stored in the
    ANSI character set, do not select this check box. This changes the display
    format only; the data is not converted.

    Specifying Column Information

    In the Column Information section, define the types and names of the
    columns in the table. The box in the upper-left corner of this section
    lists the defined columns.

    If you specified a comma-separated, tab-separated, or character-separated
    table type, a Guess button is displayed in this section. Click Guess to
    tell the driver to guess the fields. The driver then displays what it
    thinks the fields are. You can then modify the field definitions by
    clicking Modify and completing the Name, Precision, and Scale fields. If
    you do not want the driver to guess the fields, take the following steps to
    define the fields:

    a. In the Name field, type the name of the field.

    b. Open the Type box and select the data type of the field. If the field
       type is date, then you must select a date mask for the field or type one
       in.

    c. In the Precision field, type the precision of the field.

    d. In the Scale field, type the scale of the field.  The precision and
       scale values determine how numeric data is to be returned.

    e. If you specified a fixed-length table type, you may enter the length and
       offset in the Length and Offset fields, or you can specify a parse
       string. The length is the number of bytes the data takes up in storage;
       the offset is the number of bytes from the start of the table to the
       start of the field.

    f. Click Add to add this field definition to the list box.

       To modify the currently selected field in the list box, click Modify.

       To remove the currently selected field in the list box, click Remove.


ΓòÉΓòÉΓòÉ 3. Parsing Fixed Length Files ΓòÉΓòÉΓòÉ

This dialog box displays the first line of the file. You must mark where each
field begins and ends by enclosing it in brackets. These brackets indicate the
position and length of each field value in the record. You must do this for all
the fields in the table.


ΓòÉΓòÉΓòÉ 4. Date Masks ΓòÉΓòÉΓòÉ

Date masks tell the driver how a date is stored in a text file. When a value is
inserted into the text file, the date is formatted so that it matches the mask.
When reading the text file, the driver converts the formatted date into a date
data type.

The following list shows the symbols to use when specifying the date mask and
describes the output of the mask:

m
          Output the month's number (1-12).

mm
          Output a leading zero if the month number is less than 10.

mmm, Mmm, MMM
          Output the three-letter abbreviation for the month depending on the
          case of the M's (that is, jan, Jan, JAN).

mmmm, Mmmm, MMMM
          Output the full month name depending on the case of the M's (that is,
          january, january, JANUARY).

d
          Output the day number (1-31).

dd
          Output a leading zero if the day number is less than 10.

ddd, Ddd, DDD
          Output the three-letter day abbreviation depending on the case of the
          D's (that is, mon, Mon, MON).

dddd, Dddd, DDDD
          Output the day depending on the case of the D's (that is, monday,
          Monday, MONDAY).

yy
          Output the last two digits of the year.

yyyy
          Output the full four digits of the year.

J
          Output the Julian value for the date. The Julian value is the number
          of days since 4712 BC.

\ - . : , (space)
          Output special characters to separate the parts of a date.

\
          Output the next character. For example, if the mask is mm/dd/yyyy
          \A\D, the value appears as 10/01/1993 AD in the text file.

"string", 'string'
          Output the string in the text file.

For example, applying these masks to the date "1993-10-01" outputs the
following values in the text file:

The mask "yyyy-mm-dd" outputs "1993-10-01"

The mask "m/d/yy" outputs "10/1/93"