19.6.2 Correspondences between SQL data types and data descriptions

The following table shows the correspondences between the SQL data types and the data descriptions in C or C++.

Table 19‒8: Correspondences between the SQL data types and the data descriptions in C or C++.
No.	SQL data type	Data description in C or C++	Area length (bytes)
1	`CHAR(n)`	`char` `variable-name` `[n` `+` `1];`	`n` + 1
2	`VARCHAR(n)`	`a_rdb_M_VARCHAR(n)` `variable-name;`	`n` + 4
3	`INTEGER`	`long` `long` `variable-name;`	8
4	`SMALLINT`	`int` `variable-name;`	4
5	`DECIMAL(m,n)`	`unsigned` `char` `variable-name[p`^#1`];`	`p`^#1
6	`DOUBLE` `PRECISION`	`double` `variable-name;`	8
7	`DATE`	`unsigned` `char` `variable-name[4];`	4
8	`TIME(p)`^#2	`unsigned` `char` `variable-name[3` `+` `(p` `+` `1)` ÷ `2];`	3 + (`p` + 1) ÷ 2
9	`TIMESTAMP(p)`^#2	`unsigned` `char` `variable-name[7` `+` `(p` `+` `1)` ÷ `2];`	7 + (`p` + 1) ÷ 2
10	`BINARY(n)`	`unsigned` `char` `variable-name[n];`	`n`
11	`VARBINARY(n)`	`a_rdb_M_VARBINARY(n)` `variable-name;`	`n` + 2
12	`ROW`	`unsigned` `char` `variable-name[row-length`^#3`];`	`row-length`^#3

Legend:

m, n: Positive integer

#1

The value of p depends on the value of m (precision).

No.	Value of m	Value of p
1	1 ≤ `m` ≤ 4	2
2	5 ≤ `m` ≤ 8	4
3	9 ≤ `m` ≤ 16	8
4	17 ≤ `m` ≤ 38	16

#2

p indicates the fractional seconds precision and its value is 0, 3, 6, 9, or 12.

#3

The row length is the sum of the data lengths of all the columns. For details about determining the data length of a column, see Length of data storage in the topic List of data types in the manual HADB SQL Reference.

Macros used in the data descriptions are expanded as shown below.

■ a_rdb_M_VARCHAR(n) variable-name;

struct
{
  unsigned int Length ;           /* Data length */
  char Data[n] ;                  /* Character string data */
}

■ a_rdb_M_VARBINARY(n) variable-name;

struct
{
  unsigned short Length ;         /* Data length */
  unsigned char Data[n] ;         /* Binary data */
}

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