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ALLBASE/SQL converts the type of a value in the following situations: Including values of different types in the same
expression.
Moving data from a host variable to a column or a
column to a host variable of a different type.
The valid type combinations are shown in Table 7-3 “Valid Type Combinations”. Table 7-3 Valid Type Combinations | Source Data Type | Target Data Type |
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| CHAR or VARCHAR | CHAR or VARCHAR | | | DATE, TIME DATETIME, or INTERVAL when CHAR value involved in
date/time math or inserted into or compared to a date/time column | | CHAR or VARCHAR | BINARY or VARBINARY (from host variable/constant into a
binary column only) | | BINARY or VARBINARY | BINARY or VARBINARY | | BINARY or VARBINARY | CHAR or VARCHAR (from column into host variable, or
comparing a binary column with a char column or value)
| | DECIMAL, FLOAT, REAL, INTEGER, SMALLINT | Any numeric type
| | DATE, TIME, DATETIME, INTERVAL | CHAR or VARCHAR (except in LIKE predicate)
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In some cases, such as the following, data conversion can lead to overflow or
truncation: Overflow can occur during these conversions:
- FLOAT
to DECIMAL, INTEGER or SMALLINT
- FLOAT
to REAL
- REAL
to DECIMAL, INTEGER, or SMALLINT
- DECIMAL
to DECIMAL, INTEGER, or SMALLINT
- INTEGER
to DECIMAL or SMALLINT
- SMALLINT
to DECIMAL
Overflow of the integer part and truncation of the
fractional part of a number can occur during a
FLOAT-to-DECIMAL conversion, because ALLBASE/SQL aligns
the decimal points.
Truncation of the fractional part of a value occurs
during these conversions:
- DECIMAL
to SMALLINT or INTEGER
- DECIMAL
to DECIMAL when the target scale is smaller than the source scale
- FLOAT
to INTEGER, SMALLINT, DECIMAL, or REAL
- REAL
to INTEGER, SMALLINT, or DECIMAL
Truncation can occur during these conversions if
the target is too small:
- DATE, TIME, DATETIME or INTERVAL
to VARCHAR or CHAR
- CHAR
to VARCHAR, BINARY or VARBINARY
- VARCHAR
to CHAR, BINARY or VARBINARY
- VARBINARY
to BINARY, CHAR or VARCHAR
- BINARY
to VARBINARY, CHAR, or VARCHAR
When you use numeric data of different types in an
expression or comparison operation, the data type of the
lesser type is converted to that of the greater type, and
the result is expressed in the greater type. Numeric types
have the following precedence: Comparison operations or expressions
involving different numeric data types result in conversion from
one data type to another as explained in Table 7-4: Table 7-4 Conversions from Combining Different Numeric Data Types | Operations containing: | Result: |
|---|
| DECIMAL and INTEGER types only |
All participating integers are converted to
DECIMAL quantities having a precision of 10 and a scale of 0. | | DECIMAL and SMALLINT types only |
All participating SMALLINT values are converted to DECIMAL quantities
having a precision of 5 and a scale of 0. | | One item of type FLOAT |
All participating integer and decimal operands
are converted to FLOAT quantities and precision can be lost. | | One item of type REAL |
All arithmetic involving REAL operands results in a type of FLOAT.
All participating integer and decimal operands
are converted to FLOAT quantities and precision can be lost.
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