SQL/MP Programming Manual for C

Host Variables
HP NonStop SQL/MP Programming Manual for C—429847-008
2-7
Declaring and Using Host Variables
TYPE AS
specifies that the host variable will have the specified date-time (DATETIME,
DATE, TIME, or TIMESTAMP) or INTERVAL data type. If a host variable must
contain date-time or INTERVAL values, define it as a character data type. To cause
NonStop SQL/MP to handle the host variable as a scaled value, either use the
SETSCALE function or define the variable as C data type fixed.
Declaring and Using Host Variables
You can declare and use these data types as host variables:

Fixed and variable length character data types (CHAR and VARCHAR)

Structures

Decimal data types

Fixed-point data types

Date-time and INTERVAL data types
Fixed-Length Character Data
The C language uses a character array plus a null terminator (\0) to store a string
literal. Most C string-handling routines (for example, strlen and printf) require the
null terminator. Follow these guidelines when you use character arrays as host
variables for string literals.
Declaring a Character Array
When you declare a character array as a host variable, the C compiler reserves the
last byte of the array as a place holder for a null terminator. Therefore, declare a
character array one byte longer than the actual number of characters. (The INVOKE
directive automatically appends an extra byte to a character array, provided you do not
specify the CHAR_AS_ARRAY option in the SQL pragma.) This declaration is for an SQL
column up to 20 bytes long:
EXEC SQL BEGIN DECLARE SECTION;
char last_name[21]; /* 20-byte last name */
EXEC SQL END DECLARE SECTION;
...
Selecting Character Data
When selecting character data from a database to return to a host variable array,
NonStop SQL/MP does not append a null terminator to the data. Therefore, before
using the array in a C string-handling routine that requires a null terminator, you must
append a null terminator to the array. This example selects character data from the