Transfer Octet Length

The transfer octet length of a column is the maximum number of bytes returned to the application when data is transferred to its default C data type. For character data, the transfer octet length does not include space for the null-termination character. Note that the transfer octet length of a column may be different than the number of bytes required to store the data on the data source.

The transfer octet length defined for each ODBC SQL data type is shown in the following table.

SQL type identifier

Length

All character types [a]

The number of bytes required to hold the defined or maximum (for variable types) number of characters. This is the same value as the descriptor field SQL_DESC_OCTET_LENGTH.

SQL_DECIMAL SQL_NUMERIC

The number of bytes required to hold the character representation of this data. This is the maximum number of digits plus two, since the data is returned as a character string, and characters are needed for the digits, a sign, and a decimal point. For example, the transfer length of a column defined as NUMERIC(10,3) is 12.

SQL_TINYINT

1

SQL_SMALLINT

2

SQL_INTEGER

4

SQL_BIGINT

The number of bytes required to hold the character representation of this data, since this data type is returned as a character string by default. The character representation consists of 20 characters: 19 for digits and a sign, if signed, or 20 digits, if unsigned. Thus, the length is 20.

SQL_REAL

4

SQL_FLOAT

8

SQL_DOUBLE

8

SQL_BIT

1

All binary types [a]

The number of bytes required to hold the defined (for fixed types) or maximum (for variable types) number of characters.

SQL_TYPE_DATE SQL_TYPE_TIME

6 (the size of the SQL_DATE_STRUCT or SQL_TIME_STRUCT structure).

SQL_TYPE_TIMESTAMP

16 (the size of the SQL_TIMESTAMP_STRUCT structure).

All interval data types

34 (the size of the interval structure).

[a] If the driver cannot determine the column or parameter length for variable types, it returns SQL_NO_TOTAL.