ct_bind versus dbbind

DB-Library provides four similar bind routines:

dbbind – binds regular row columns
dbbind_ps (version 10.0 and later) – same as dbbind but provides precision and scale support for decimal and numeric datatypes
dbaltbind – binds compute row columns
dbaltbind_ps (version 10.0 and later) – same as dbaltbind_ps but provides precision and scale support for decimal and numeric datatypes

If you understand how dbbind_ps usage maps to ct_bind usage, you will be able to convert any other DB-Library bind routine call to an equivalent ct_bind call. dbbind_ps is an enhancement of dbbind. It takes as an additional parameter a DBTYPEINFO structure to convey precision and scale information about numeric and decimal datatypes. For datatypes other than numeric and decimal, the additional parameter is ignored, and dbbind_ps is equivalent to dbbind.

Table 5-10 compares dbbind_ps parameters to ct_bind parameters:

**Table 5-10: dbbind_ps parameters vs. ct_bind parameters**
dbbind_ps parameter	Parameter description	ct_bind parameter	Parameter description
dbproc	A pointer to the DBPROCESS structure for this connection.	cmd	A pointer to the CS_COMMAND structure.
column	An integer representing the number of the column to bind.	item	An integer representing the number of the column to bind.
		datafmt	A pointer to the CS_DATAFMT structure that describes the destination variable.
vartype	A symbolic value corresponding to the datatype of the program variable that will receive the copy of the data from the DBPROCESS.	datafmt→datatype	datatype is a symbol (CS_xxx_TYPE) representing the datatype of the destination variable.
vartype		datafmt→format	format is a symbol describing the destination format of character or binary data.
varlen	The length of the program variable in bytes.	datafmt→maxlength	The length of the buffer destination variable in bytes.
typeinfo→precision typeinfo→scale	typeinfo is a pointer to a DBTYPEINFO structure, which contains information about the precision and scale of decimal or numeric data. typeinfo of NULL is equivalent to calling dbbind.	datafmt→precision datafmt→scale	The precision and scale to be used for the destination variable. If the source data is the same type as the destination, then scale and precision can be set to CS_SRC_VALUE to pick up the value from the source data.
(none)		datafmt→count	The number of rows to copy to program variables per ct_fetch call. (Set to 1 if not binding to arrays.)
varaddr	The address of the program variable to which the data is to be copied.	buffer	The address of an array of datafmt→count variables, each of which is of size datafmt→maxlength.
(none)		copied	The address of an array of datafmt→count integer variables, to be filled at fetch time with the lengths of the copied data (optional).
(none—the routines dbnullbind and dbanullbind bind indicator variables)		indicator	The address of an array of datafmt→count CS_SMALLINT variables, to be filled at fetch time to indicate certain conditions about the fetched data.

The mapping of DB-Library vartype values to Client-Library CS_DATAFMT datatype and format values is straightforward for all of the fixed-length datatypes.

For character and binary types, the mapping is shown in Table 5-11:

**Table 5-11: DB-Library vartype vs. CS_DATAFMT datatype and format fields**
Program variable type	DB-Library vartype	CS_DATAFMT→datatype	CS_DATAFMT→format
DBCHAR	CHARBIND	CS_CHAR_TYPE	CS_FMT_PADBLANK
DBCHAR	STRINGBIND	CS_CHAR_TYPE	CS_FMT_NULLTERM
DBCHAR	NTBSTRINGBIND	CS_CHAR_TYPE	CS_FMT_NULLTERM Client-Library does not trim trailing blanks.
DBVARYCHAR	VARYCHARBIND	CS_VARCHAR_TYPE	CS_FMT_UNUSED
DBBINARY	BINARYBIND	CS_BINARY_TYPE	CS_FMT_PADNULL
DBVARYBIN	VARYBINBIND	CS_VARBINARY_TYPE	CS_FMT_UNUSED

With dbbind, passing NTBSTRINGBIND for vartype causes DB-Library to trim trailing blanks from the destination string. Client-Library lacks a format option to strip trailing blanks.

For Adaptive Server column data, only values that originate as a fixed-length char column will have trailing blanks to begin with, because Adaptive Server trims trailing blanks from varchar columns on entry.

If a DB-Library application relies on NTBSTRINGBIND behavior, the Client-Library version of the application must trim any trailing blanks itself.