Data types for procedures, functions, and methods in C and C++ embedded SQL applications

There is a mapping between C and C++ and Db2® data types. When you are writing your embedded SQL application, you must be aware of this mapping to ensure that you do not have unexpected data type conversions or data truncation.

The following table lists the supported mappings between SQL data types and C and C++ data types for procedures, UDFs, and methods.

Table 1. SQL Data Types Mapped to C and C++ Declarations
SQL Column Type1 C and C++ Data Type SQL Column Type Description
SMALLINT
(500 or 501)
short 16-bit signed integer
INTEGER
(496 or 497)
sqlint32 32-bit signed integer
BIGINT
(492 or 493)
sqlint64 64-bit signed integer
REAL
(480 or 481)
float Single-precision floating point
DOUBLE
(480 or 481)
double Double-precision floating point
DECIMAL(p,s)
(484 or 485)
Not supported

To pass a decimal value, define the parameter to be of a data type castable from DECIMAL (for example CHAR or DOUBLE) and explicitly cast the argument to this type.
CHAR(n)
(452 or 453)
char[n+1] where n is large enough to hold the data
1<=n<=254
 Fixed-length, null-terminated character string
CHAR(n) FOR BIT DATA
(452 or 453)
char[n+1] where n is large enough to hold the data
1<=n<=254
 Fixed-length character string
VARCHAR(n)
(448 or 449) (460 or 461)
 char[n+1] where n is large enough to hold the data
1<=n<=32 672
 Null-terminated varying length string
VARCHAR(n) FOR BIT DATA
(448 or 449)
struct {
  sqluint16 length;
  char[n]
}
 
1<=n<=32 672
 Not null-terminated varying length character string
LONG VARCHAR2
(456 or 457)
struct {
  sqluint16 length;
  char[n]
}
 
32 673<=n<=32 700
 Not null-terminated varying length character string
CLOB(n)
(408 or 409)
struct {
  sqluint32 length;
  char     data[n];
}
 
1<=n<=2 147 483 647
 Not null-terminated varying length character string with 4-byte string length indicator
BINARY(n)
(912 or 913)
char[n+1] where n is large enough to hold the data
1<=n<=254
 Fixed-length binary string
VARBINARY(n)
(908 or 909)
struct {
  sqluint16 length;
  char[n]
}
 
1<=n<=32 672
 Not null-terminated varying length binary string
BLOB(n)
(404 or 405)
struct {
  sqluint32 length;
  char      data[n];
}
 
1<=n<=2 147 483 647
 Not null-terminated varying binary string with 4-byte string length indicator
DATE
(384 or 385)
 char[11] Null-terminated character form
TIME
(388 or 389)
 char[9] Null-terminated character form
TIMESTAMP(p)
(392 or 393)
 char[p+21] where p is large enough to hold the data
0<=p<=12
 Null-terminated character form
XML
(988/989)
Not supported
 This descriptor type value (988/989) will be defined to be used in the SQLDA for describe, and to indicate XML Data (in its serialized form). Existing character and binary types (including LOBs and LOB file reference types) can also be used to fetch and insert the data (dynamic SQL only)
Note: The following data types are only available in the DBCS or EUC environment when precompiled with the WCHARTYPE NOCONVERT option.
Table 2. SQL Data Types Mapped to C and C++ Declarations
SQL Column Type1 C and C++ Data Type SQL Column Type Description
GRAPHIC(n)
(468 or 469)
 sqldbchar[n+1] where n is large enough to hold the data
1<=n<=127
 Fixed-length, null-terminated double-byte character string
VARGRAPHIC(n)
(400® or 401)
 sqldbchar[n+1] where n is large enough to hold the data
1<=n<=16 336
 Not null-terminated, variable-length double-byte character string
LONG VARGRAPHIC2
(472 or 473)
struct {
  sqluint16 length;
  sqldbchar[n]
}
 
16 337<=n<=16 350
 Not null-terminated, variable-length double-byte character string
DBCLOB(n)
(412 or 413)
struct {
  sqluint32  length;
  sqldbchar data[n];
}
 
1<=n<=1 073 741 823
 Not null-terminated varying length character string with 4-byte string length indicator
Note:
  1. The first number under SQL Column Type indicates that an indicator variable is not provided, and the second number indicates that an indicator variable is provided. An indicator variable is needed to indicate NULL values, or to hold the length of a truncated string. These are the values that will be displayed in the SQLTYPE field of the SQLDA for these data types.
  2. The LONG VARCHAR and LONG VARGRAPHIC data types are deprecated and might be removed in a future release. Choose the CLOB or DBCLOB data type instead.