MariaDB Connector/C Data Structures

This page describes the public data structures used by MariaDB Connector/C.

MYSQL

The MYSQL structure represents one database connection and is used by most of MariaDB Connector/C's API functions. The MYSQL structure needs to be allocated and initialized by the mysql_init() API function. It will be released by the mysql_close() function.

The MYSQL structure should be considered as opaque; copying or changing values of its members might produce unexpected results, errors or program crashes.

MYSQL_RES

The MYSQL_RES structure represents a result set which contains data and metadata information. It will be returned by the mysql_use_result(), mysql_store_result() and mysql_stmt_result_metadata() API functions and needs to be released by mysql_free_result().

The MYSQL_RES structure should be considered as opaque; copying or changing values of its members might produce unexpected results, errors or program crashes.

MYSQL_ROW

MYSQL_ROW represents an array of character pointers, pointing to the columns of the actual data row. Data will be received by the mysql_fetch_row() function. The size of the array is the number of columns for the current row.

After freeing the result set with mysql_free_result() MYSQL_ROW becomes invalid.

MYSQL_STMT

The MYSQL_STMT structure represents a prepared statement handle and is used by MariaDB Connector/C's prepared statement API functions. The MYSQL_STMT structure needs to be allocated and initialized by the mysql_stmt_init() function and needs to be released by the mysql_stmt_close() function.

The MYSQL_STMT structure should be considered as opaque; copying or changing values of its members might produce unexpected results, errors or program crashes.

MYSQL_FIELD

The MYSQL_FIELD structure describes the metadata of a column. It can be obtained by the mysql_fetch_field() function.

It has the following members:

char *	name	The name of the column
unsigned int	name_length	The length of column name
char *	org_name	The original name of the column
unsigned int	org_name_length	The length of original column name
char *	table	The name of the table
unsigned int	table_length	The length of table name
char *	org_table	The original name of the table
unsigned int	org_table_length	The length of original table name
char *	db	The name of the database (schema)
unsigned int	db_length	The length of database name
char *	catalog	The catalog name (always 'def')
unsigned int	catalog_length	The length of catalog name
char *	def	default value
unsigned int	def_length	The length of default value
unsigned int	length	The length (width) of the column definition
unsigned int	max_length	The maximum length of the column value
unsigned int	flags	Flags
unsigned int	decimals	Number of decimals
enum enum_field_types	type	Field type

MYSQL_BIND

The MYSQL_BIND structure is used to provide parameters for prepared statements or to receive output column value from prepared statements.

unsigned long *	length	Pointer for the length of the buffer (not used for parameters)
my_bool *	is_nulll	Pointer which indicates if column is NULL (not used for parameters)
my_bool *	error	Pointer which indicates if an error occured
void *	buffer	Data buffer which contains or receives data
char *	u.indicator	Array of indicator variables for bulk operation parameter
unsigned long	buffer_length	Length of buffer
enum enum_field_types	buffer_type	Buffer type
unsigned long	length_value	Used if length pointer is NULL
my_bool	error_value	Used if error pointer is NULL
my_bool	is_null_value	Used if is_null pointer is NULL
my_bool	is_unsigned	Set if integer type is unsigned
my_bool	is_null_value	Used if value is NULL

MYSQL_TIME

The MYSQL_TIME structure is used for date and time values in prepared statements. It has the following members:

unsigned int	year	Year
unsigned int	month	Month
unsigned int	day	Day
unsigned int	hour	Hour
unsigned int	minute	Minute
unsigned int	second	Second
unsigned long	second_part	Fractional seconds (max. 6 digits)
my_bool	neg	Negative value
enum enum_mysql_timestamp_type	time_type	Type