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Summary:
See also: Data Types.
The runtime system performs data conversion implicitly without objection,
as long as the data conversion is valid. For example, when you assign a number expression
to a character variable, the runtime system converts the resulting number to
a literal string.
Conversion rules apply to variable assignment, function parameters, and
returned values.
Warnings:
- The global STATUS
variable is not set when a conversion error occurs unless you have enabled
ANY ERROR detection with the WHENEVER
instruction. By default, when a conversion error occurs, STATUS is zero and
the resulting value is NULL.
- Data conversions from or to character string values involve environment
and locale settings like DBDATE, DBFORMAT.
The following table shows which pairs of data types are compatible.
Conversion table:
|
Columns represent source data types and lines represent
receiving data types.
|
| |
char |
varchar |
string |
integer |
smallint |
float |
smallfloat |
decimal |
money |
date |
datetime |
interval |
text |
byte |
| char |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1, 8 |
1, 9 |
1 |
1 |
15 |
15 |
| varchar |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1, 8 |
1, 9 |
1 |
1 |
15 |
15 |
| string |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1, 8 |
1, 9 |
1 |
1 |
15 |
15 |
| integer |
2, 3 |
2, 3 |
2, 3 |
|
|
3, 4 |
3, 4 |
3, 4 |
3, 4 |
11 |
15 |
15 |
15 |
15 |
| smallint |
2, 3 |
2, 3 |
2, 3 |
3 |
|
3, 4 |
3, 4 |
3, 4 |
3, 4 |
3, 11 |
15 |
15 |
15 |
15 |
| float |
2, 3, 5 |
2, 3, 5 |
2, 3, 5 |
10 |
10 |
|
|
3 |
3 |
11 |
15 |
15 |
15 |
15 |
| smallfloat |
2, 3, 5 |
2, 3, 5 |
2, 3, 5 |
5, 10 |
10 |
5 |
|
3, 5 |
3, 5 |
5, 11 |
15 |
15 |
15 |
15 |
| decimal |
2, 3, 6 |
2, 3, 6 |
2, 3, 6 |
3 |
3 |
3, 6 |
3, 6 |
3, 6 |
3, 6 |
3, 11 |
15 |
15 |
15 |
15 |
| money |
2, 3, 6 |
2, 3, 6 |
2, 3, 6 |
3 |
3 |
3, 6 |
3, 6 |
3, 6 |
3, 6 |
3, 11 |
15 |
15 |
15 |
15 |
| date |
2 |
2 |
2 |
11 |
11 |
3,4,11 |
3,4,11 |
3,4,11 |
3,4,11 |
|
12, 14 |
15 |
15 |
15 |
| datetime |
2 |
2 |
2 |
15 |
15 |
15 |
15 |
15 |
15 |
13, 14 |
7, 14 |
15 |
15 |
15 |
| interval |
2 |
2 |
2 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
3, 7 |
15 |
15 |
| text |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
|
15 |
| byte |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
|
Notes:
- If the result of converting a value to a character string is longer than
the receiving variable, the character string is truncated from the right.
- Character string values must depict a literal of the receiving data type.
- If the value exceeds the range of the receiving data type, an overflow
error occurs.
- Any fractional part of the value is truncated.
- If the passed value contains more significant digits than the receiving
data type supports, low-order digits are discarded.
- If the passed value contains more fractional digits than the receiving
data type supports, low-order digits are discarded.
- Differences in qualifiers can cause truncation from the left or right.
- DBMONEY and DBFORMAT control the format of the converted string.
- DBFORMAT, DBDATE, or GL_DATE controls the format of the result.
- Rounding errors can produce an assigned value with fractional parts.
- An integer value corresponding to a count of days is assigned.
- An implicit EXTEND( value, YEAR TO
DAY ) is performed.
- The DATE becomes a DATETIME
YEAR TO DAY literal before assignment.
- If the passed value has less precision than the receiving variable, any
missing time unit values are obtained from the system clock.
- Unsupported conversion.