SQL/MP Programming Manual for C

Host Variables

HP NonStop SQL/MP Programming Manual for C—429847-008

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Decimal Data Types

Use the DECIMAL data type for ASCII numeric data. Because a decimal string is

actually a fixed-length character string that contains only ASCII digits, considerations

for fixed-length character strings also apply to decimal strings. Follow these guidelines

when you use character arrays as host variables for DECIMAL data:



Declare a decimal array one byte larger than the number of digits you expect to

store in the array.



Append a null terminator to an SQL/MP decimal string before you process it as a

C decimal string.



Right justify a C decimal string and pad the string on the left with ASCII zeros up to

the length of the corresponding SQL column before you insert the value into the

database.

HP C does not support direct manipulation of decimal strings. To perform C arithmetic

operations on SQL columns of DECIMAL data type, first convert the column to an

integral type using the dec_to_longlong routine.

HP C also provides the longlong_to_dec routine to convert type long long to type

decimal. Although the longlong_to_dec routine supports a variety of formats for

signed decimal strings, NonStop SQL/MP supports only the embedded leading signed

format. Therefore, always specify the embedded leading signed format when you

intend to pass the converted decimal string to NonStop SQL/MP.

For more information about C routines, see the C/C++ Programmer’s Guide.

Fixed-Point Data Types

HP C does not have a data type that maps directly to a fixed-point number (that is, an

SQL numeric data type with scale). If you transfer fixed-point values to integral or

floating-point host variables, consider these guidelines:



When you transfer a fixed-point value to a host variable of floating-point data type,

NonStop SQL/MP converts the fixed-point value to a floating-point value and

generates a warning to indicate a loss of precision.



When you transfer a fixed-point value into an integer host variable, NonStop

SQL/MP stores the integral part of the value and generates a warning to indicate a

loss of data (the fractional part). To retain the fractional part, use the SETSCALE

function to scale the fixed-point value before transferring it to the host variable.

SETSCALE Function

The SETSCALE function directs NonStop SQL/MP to use a host variable in SQL

statements as if the host variable were declared with a specific scale. Use the

SETSCALE function for these operations:



To insert scaled values (for example, prices) into a database