Data model editor: the different types of items

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Data model editor: the different types of items

Types of items

The different types of items proposed in the data model editor are as follows:

Type	Used to store:

Text	alphanumeric characters String: a character string containing up to 65.535 characters. This character string is in Ansi format. Text memo: a character string of 4 GB maximum. The RTF format is supported. This text memo is in Ansi format. Character: a single character (initialized by a binary 0, Charact(0)). Unicode: a character string in Unicode format. Unicode text memo: a character string of 4 GB maximum. This text memo is in Unicode format.
Numeric	a numeric value Signed 1-byte integer: value included between -128 and 127 Signed 2-byte integer: value included between -32.768 and 32.767 Signed 4-byte integer: value included between -2.147.483.648 and 2.147.483.647 Signed 8-byte integer: value included between -9.223.372.036.854.775.808 and 9.223.372.036.854.775.807 Unsigned 1-byte integer: value included between 0 and 255 Unsigned 2-byte integer: value included between 0 and 65.535 Unsigned 4-byte integer: value included between 0 and 4.294.967.296 Unsigned 8-byte integer: value included between 0 and 18.446.744.073.709.551.615 4-byte real: value included between -3,4e+38 and +3.4e+38 8-byte real: value included between -1,79e+308 and +1.79e+308 Decimal (WLanguage numeric): a decimal can contain up to 38 significant digits.
Currency	a currency A currency can contain up to 24 significant digits (up to 18 digits for the integer part and up to 6 digits for the decimal part) and it can take a value between -604 462 909 807 314 587,353 087 and +604 462 909 807 314 587,353 087.
Date	a date or a duration Date (YYYYMMDD): a date in YYYYMMDD format (dates included between 01/01/0001 and 31/12/9999) Date and Time: a date-time (included between 01/01/0001 at 00:00 and 31/12/9999 at 23:59). The precision is up to the millisecond. Duration: a duration in milliseconds (included between -9.223.372.036.854.775.808 and 9.223.372.036.854.775.807).
Time	a time Time (HH): Time included between 00H and 23H Time (HHMM): Time included between 00H00 and 23H59. The precision is up to the minute. Time (HHMMSS): Time included between 00H00min00ss and 23H59mn59ss. The precision is up to the second. Time (HHMMSSCC): Time included between 00H00min00ss00hs and 23H59mn59ss59hs. The precision is up to the tenth of a second. Tip: To keep a time with a precision to the hundredth of a second, use the "Date and Time" type.
Boolean	a boolean (1: True and 0: False)
Sound, image, binary, ...	a binary file or string Image (binary memo): an image file Sound (binary memo): a sound file OLE (binary memo): an OLE file Other binary memo: any type of file Binary string: a string in binary format
Check Box	a value associated with a Check Box control Check Box: a boolean (1: True and 0: False) Unsigned 1-byte integer: value included between 0 and 255
Radio Button, List Box, Combo Box	a value associated with a Radio Button control, a List Box control or a Combo Box control. You have the ability to select the following sub-type: 1-byte integer: a subscript corresponding to a list of values. The value of this subscript is included between -128 and 127 2-byte integer: a subscript corresponding to a list of values. The value of this subscript is included between -32.768 and 32.767 4-byte integer: a subscript corresponding to a list of values. The value of this subscript is included between -2.147.483.648 and 2.147.483.647 Unsigned 1-byte integer: a subscript corresponding to a list of values. The value of this subscript is included between 0 and 255
Automatic ID	the identifier of each file record. Its value is automatically updated by the engine of the HFSQL database. Automatic identifier (4 bytes): the identifier of each record (value included between 0 and 2.147.483.647) This type corresponds to the "Identifier" type of WINDEV 5.5 Automatic identifier (8 bytes): the identifier of each record (value included between 0 and 9.223.372.036.854.775.807) Versions 24 and later Automatic UUID (128 bits): the identifier of each record corresponds to a 128-bit UUID. In this case, the UUID is used to obtain a non-sequential unique identifier. New in version 24 Automatic UUID (128 bits): the identifier of each record corresponds to a 128-bit UUID. In this case, the UUID is used to obtain a non-sequential unique identifier. Automatic UUID (128 bits): the identifier of each record corresponds to a 128-bit UUID. In this case, the UUID is used to obtain a non-sequential unique identifier. Versions 24 and later Automatic UUID (256 bits): the identifier of each record corresponds to a 256-bit UUID. In this case, the UUID is used to obtain a non-sequential unique identifier. New in version 24 Automatic UUID (256 bits): the identifier of each record corresponds to a 256-bit UUID. In this case, the UUID is used to obtain a non-sequential unique identifier. Automatic UUID (256 bits): the identifier of each record corresponds to a 256-bit UUID. In this case, the UUID is used to obtain a non-sequential unique identifier. Versions 24 and later Remark: The same record can have an automatic UUID and an automatic Identifier (for example, to simplify migration). New in version 24 Remark: The same record can have an automatic UUID and an automatic Identifier (for example, to simplify migration). Remark: The same record can have an automatic UUID and an automatic Identifier (for example, to simplify migration). Remark: From version 19, HFSQL is the new name of HyperFileSQL.
XML	an XML character string (4 GB maximum). This string is stored as a text memo.
Full-text index	the different elements of the full-text index. The full-text index can include text items or text memo items. See Search and full-text index for more details.
Enumeration, Combination	Enumeration: an integer value among the possible values defined in the enumeration associated with the item. Combination: an integer value representing a combination of possible values defined in the combination associated with the item. See Enumeration and Combination items for more details.
Versions 21 and later Formula New in version 21 Formula Formula	a character string in SQL language representing a calculation formula. The formula can use SQL functions and/or WLanguage functions (WL.). Only the formula is stored, the value is calculated when accessing the record in read-only. For example, calculating the age from the DateOfBirth item of the file. The value will be calculated in the data file directly. CAST(TO_CHAR(SYSDATE,'YYYY') AS int)-CAST(TO_CHAR(dateofbirth,'YYYY') AS int) However, the calculated value can be stored in the file in order not to have to perform the calculation again. You have the ability to store the formula in Unicode: the calculation will be faster but a bigger space will be occupied by the formula. If the record is modified, the calculation formula is re-run in order to update the buffer of the data file with the new value. Caution: The NULL management complies with the SQL standard. For example, if an expression adds the NULL value to a value, the result corresponds to the NULL value.
Versions 21 and later Timestamp New in version 21 Timestamp Timestamp	a DateTime or a Date or a Time representing the creation date of the record or the date of the last modification performed on the record. You can select: whether the creation date or the last modification date must be saved. whether the local time or the UTC time must be used. This type of item is also called "Automatic DateTime item".
Versions 24 and later UUID New in version 24 UUID UUID	a UUID. A UUID (Universal Unique IDentifier) is a random number deemed unique. A UUID is useful to easily and reliably identify any element. You can select: a 128-bit UUID. This type of UUID item complies with the 128-bit RFC 4122 standard. Only the 128-bit UUID is standardized. a 256-bit UUID. To manage a UUID automatic identifier (automatically initialized by HFSQL), it is necessary to use an "Identifier" item whose sub-type is "Automatic UUID". Remark: The major interest of UUID is to allow anonymization and pseudonymization, useful for compliance with the GDPR standard. The UUID also allows you to manage cryptocurrency identifiers.
Versions 24 and later JSON New in version 24 JSON JSON	a JSON string. This type of item can contain NULL, an empty string or a valid JSON. JSON is automatically verified when the record is written. This type of item is used with JSON SQL functions in particular.

Remark: The Unicode items are managed by the wdxxxuni.dll library. This library is not available in WINDEV Mobile.

Array items

Some types of items can correspond to an array: the item content will be subscripted.

To define an Array item:

Create an item. The following types of items can correspond to an array: Text, Numeric, Currency, Date, Time, Boolean, Check Box.
In the item description:
- Check "Array" and specify the array dimension.
  Caution: The array dimension is fixed. The corresponding space is reserved even if the item is not filled.
- The actual item size is displayed.
Specify (if necessary) the default values of each array element.
Validate.

Remarks:

The first subscript starts from 1.
The following syntax is used to handle array items: <File name>.<Item name>[<Subscript>]
Caution: This type of item is kept for backward compatibility. Most of SQL databases do not support this type of items.