6.2.1 C API Prepared Statement Type Codes

The buffer_type member of MYSQL_BIND structures indicates the data type of the C language variable bound to a statement parameter or result set column. For input, buffer_type indicates the type of the variable containing the value to be sent to the server. For output, it indicates the type of the variable into which a value received from the server should be stored.

The following table shows the permissible values for the buffer_type member of MYSQL_BIND structures for input values sent to the server. The table shows the C variable types that you can use, the corresponding type codes, and the SQL data types for which the supplied value can be used without conversion. Choose the buffer_type value according to the data type of the C language variable that you are binding. For the integer types, you should also set the is_unsigned member to indicate whether the variable is signed or unsigned.

Table 6.1 Permissible Input Data Types for MYSQL_BIND Structures

Input Variable C Type	buffer_type Value	SQL Type of Destination Value
signed char	MYSQL_TYPE_TINY	TINYINT
short int	MYSQL_TYPE_SHORT	SMALLINT
int	MYSQL_TYPE_LONG	INT
long long int	MYSQL_TYPE_LONGLONG	BIGINT
float	MYSQL_TYPE_FLOAT	FLOAT
double	MYSQL_TYPE_DOUBLE	DOUBLE
MYSQL_TIME	MYSQL_TYPE_TIME	TIME
MYSQL_TIME	MYSQL_TYPE_DATE	DATE
MYSQL_TIME	MYSQL_TYPE_DATETIME	DATETIME
MYSQL_TIME	MYSQL_TYPE_TIMESTAMP	TIMESTAMP
char[]	MYSQL_TYPE_STRING	TEXT, CHAR, VARCHAR
char[]	MYSQL_TYPE_BLOB	BLOB, BINARY, VARBINARY
	MYSQL_TYPE_NULL	NULL

Use MYSQL_TYPE_NULL as indicated in the description for the is_null member in Section 6.2, “C API Prepared Statement Data Structures”.

For input string data, use MYSQL_TYPE_STRING or MYSQL_TYPE_BLOB depending on whether the value is a character (nonbinary) or binary string:

• MYSQL_TYPE_STRING indicates character input string data. The value is assumed to be in the character set indicated by the character_set_client system variable. If the server stores the value into a column with a different character set, it converts the value to that character set.

• MYSQL_TYPE_BLOB indicates binary input string data. The value is treated as having the binary character set. That is, it is treated as a byte string and no conversion occurs.

The following table shows the permissible values for the buffer_type member of MYSQL_BIND structures for output values received from the server. The table shows the SQL types of received values, the corresponding type codes that such values have in result set metadata, and the recommended C language data types to bind to the MYSQL_BIND structure to receive the SQL values without conversion. Choose the buffer_type value according to the data type of the C language variable that you are binding. For the integer types, you should also set the is_unsigned member to indicate whether the variable is signed or unsigned.

Table 6.2 Permissible Output Data Types for MYSQL_BIND Structures

SQL Type of Received Value	buffer_type Value	Output Variable C Type
TINYINT	MYSQL_TYPE_TINY	signed char
SMALLINT	MYSQL_TYPE_SHORT	short int
MEDIUMINT	MYSQL_TYPE_INT24	int
INT	MYSQL_TYPE_LONG	int
BIGINT	MYSQL_TYPE_LONGLONG	long long int
FLOAT	MYSQL_TYPE_FLOAT	float
DOUBLE	MYSQL_TYPE_DOUBLE	double
DECIMAL	MYSQL_TYPE_NEWDECIMAL	char[]
YEAR	MYSQL_TYPE_SHORT	short int
TIME	MYSQL_TYPE_TIME	MYSQL_TIME
DATE	MYSQL_TYPE_DATE	MYSQL_TIME
DATETIME	MYSQL_TYPE_DATETIME	MYSQL_TIME
TIMESTAMP	MYSQL_TYPE_TIMESTAMP	MYSQL_TIME
CHAR, BINARY	MYSQL_TYPE_STRING	char[]
VARCHAR, VARBINARY	MYSQL_TYPE_VAR_STRING	char[]
TINYBLOB, TINYTEXT	MYSQL_TYPE_TINY_BLOB	char[]
BLOB, TEXT	MYSQL_TYPE_BLOB	char[]
MEDIUMBLOB, MEDIUMTEXT	MYSQL_TYPE_MEDIUM_BLOB	char[]
LONGBLOB, LONGTEXT	MYSQL_TYPE_LONG_BLOB	char[]
BIT	MYSQL_TYPE_BIT	char[]