4.2. Type Conversions

Data types may be converted from one form to another either explicitly or implicitly. Implicit conversions automatically occur in criteria and expressions to ease development. Explicit data type conversions require the use of the CONVERT function or CAST keyword.

Type Conversion Considerations

Any type may be implicitly converted to the OBJECT type.
The OBJECT type may be explicitly converted to any other type.
The NULL value may be converted to any type.
Any valid implicit conversion is also a valid explicit conversion.
Situations involving literal values that would normally require explicit conversions may have the explicit conversion applied implicitly if no loss of information occurs.
When JBoss Data Virtualization detects that an explicit conversion can not be applied implicitly in criteria, the criteria will be treated as false. For example:
```
SELECT * FROM my.table WHERE created_by = 'not a date'
```
```
SELECT * FROM my.table WHERE created_by = 'not a date'
```
Copy to Clipboard Toggle word wrap
Given that created_by is typed as date, rather than converting 'not a date' to a date value, the criteria will remain as a string comparison and therefore be false.
Explicit conversions that are not allowed between two types will result in an exception before execution. Allowed explicit conversions may still fail during processing if the runtime values are not actually convertible.
Warning
The JBoss Data Virtualization conversions of float/double/bigdecimal/timestamp to string rely on the JDBC/Java defined output formats. Pushdown behavior attempts to mimic these results, but may vary depending upon the actual source type and conversion logic. Care must be taken to not assume the string form in criteria or other places where a variation may cause different results.

Expand

Table 4.2. Type Conversions
Source Type	Valid Implicit Target Types	Valid Explicit Target Types
string	clob	char, boolean, byte, short, integer, long, biginteger, float, double, bigdecimal, xml ^[a]
char	string
boolean	string, byte, short, integer, long, biginteger, float, double, bigdecimal
byte	string, short, integer, long, biginteger, float, double, bigdecimal	boolean
short	string, integer, long, biginteger, float, double, bigdecimal	boolean, byte
integer	string, long, biginteger, double, bigdecimal	boolean, byte, short, float
long	string, biginteger, bigdecimal	boolean, byte, short, integer, float, double
biginteger	string, bigdecimal	boolean, byte, short, integer, long, float, double
bigdecimal	string	boolean, byte, short, integer, long, biginteger, float, double
date	string, timestamp
time	string, timestamp
timestamp	string	date, time
clob		string
xml		string ^[b]
^[a] string to xml is equivlant to XMLPARSE(DOCUMENT exp) - see Section 3.4.14, “XML Functions”. ^[b] xml to string is equivalent to XMLSERIALIZE(exp AS STRING) - see Section 3.4.14, “XML Functions”.

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4.2. Type Conversions

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