Field Type Conversions

LANSA Technical

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Field Type Conversions

Following are the basic field type groupings used in LANSA:

Character/String	Store alpha data that is either SBCS, mixed SBCS and DBCS, or DBCS-only. Includes types Alpha, String, Char, and CLOB.
Unicode Character/String	Store alpha data in Unicode. (Character/String are stored in the native codepage.) Multiple languages can be handled without data loss. Includes types NChar and NVarChar.
Numeric	Store numeric data in a variety of formats. Includes types Signed, Packed, Integer, and Float.
Date/Time	Store date and time data. Includes types Date, Time, DateTime.
Binary	Store binary data. (This data is not subject to codepage conversion.) Includes types Binary, VarBinary, BLOB.
LOB	Store very large character or binary data. Includes types CLOB, BLOB.
Boolean	Store a True or False value.

The following table summarizes field conversions between groups. Yes indicates that conversion between the field type groups is allowed. It does not indicate that conversion will always be successful. For example, you cannot convert DBCS data to SBCS data, or a value like "Hello world" to a Numeric.

General Conversion Rules

From: To:	Character	Unicode Character	Numeric	Date/Time	Binary	LOB 4	Boolean
Character	Yes	Yes ⁵	Yes ¹	Yes ¹	Yes	Yes	Yes
Unicode Character	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Numeric	Yes	Yes	Yes	Yes ²	No	No	Yes
Date/Time	Yes	Yes	Yes ²	Yes ³	No	No	No
Binary	Yes	Yes	No	No	Yes	No	No
LOB 4	Yes	Yes ⁵	No	No	Yes	Yes	No
Boolean	Yes	Yes	Yes	No	No	No	Yes

Table notes:

1. CLOBs are treated as file pointers, so do not support conversion to a Numeric or Date/Time field type.

2. No support for conversion

between Integer or Float and the Date/Time field types

of a numeric type directly to a DateTime, as there is no way to determine if the type should be setting the Date or Time portion of the DateTime.

3. DateTime -> Date and DateTime -> Time are obvious.

The default Date is 1900-01-01 and the default time is midnight (00:00:00). Therefore:

Date -> DateTime sets the time part to midnight

Time -> DateTime sets the date part to 1900-01-01

Date -> Time always results in midnight

Time -> Date always results in 1900-01-01

4. The "value" for a LOB is a filename. Thus, when converting it is the filenames that are being copied, not the data. If an invalid filename is copied to a LOB, an error will occur at some stage.

5. When converting a Unicode string to a native string, the intrinsic .AsNativeString may need to be used.

Ý 1.1.1 Field Type Considerations

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