SQL/MX Programming Manual for Java

SQLJ Programming

HP NonStop SQL/MX Programming Manual for Java—523726-003

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Floating-Point Data Types

Like JDBC/MX and other Java programs, SQLJ programs handle all floating-point data

in IEEE floating-point format. SQL/MX statements embedded in an SQLJ program can

query both SQL/MX and SQL/MP format tables. Each type of table stores floating-point

data in a different format.

SQL/MX Floating-Point Format

In SQL/MX tables, floating-point values are stored in IEEE floating-point format.

Conversion of the floating-point format does not occur when an SQLJ program queries

floating-point values in SQL/MX tables.

SQL/MP Floating-Point Format

In SQL/MP tables, floating-point values are stored in Tandem floating-point format.

When an SQLJ program assigns a floating-point value from an SQL/MP column to a

Java host variable, SQL/MX converts the Tandem floating-point format to IEEE

floating-point format. Likewise, when an SQLJ program assigns a floating-point value

from a Java host variable to an SQL/MP column, SQL/MX converts the IEEE floating-

point format to Tandem floating-point format.

Conversion Between Tandem and IEEE Floating-Point Formats

When converting a Tandem floating-point data type to the corresponding IEEE data

type, all Tandem floating-point data types are converted to IEEE DOUBLE

representation. Despite this conversion, the precision of Tandem floating-point data

types are maintained correctly in IEEE floating-point format. A Tandem REAL or

FLOAT with precision between 1 and 22 cannot be converted to IEEE REAL because

the Tandem exponent will not fit in an IEEE REAL data type. Although no equivalent

exists for single-precision Tandem REAL and FLOAT in IEEE floating-point format, the

conversion to IEEE DOUBLE preserves the precision and the exponent.

If you want a small floating-point data type with a smaller exponent and less storage,

consider declaring the host variables as float or java.lang.Float. If you want a

larger exponent and more precision, consider declaring the host variables as double

or java.lang.Double.

For more information about floating-point data types, see the SQL/MX Reference

Manual, JDBC Driver for SQL/MX Programmer's Reference, and NonStop Server for

Java Programmer's Reference.