datastructures

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.

Warning:
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() or mysql_store_result API functions and needs to be released by mysql_free_result().

Warning:
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, which can be determined by mysql_field_count() API function.

Warning:
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.

Warning:
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:

Type	Member	Description
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.

Type	Member	Description
unsigned long *	length	Pointer for the length of the buffer (not used for parameters)
my_bool *	is_null	Pointer which indicates if column is NULL (not used for parameters)
my_bool *	error	Pointer which indicates if an error occurred
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	[[library/mariadb-connectorc-types-and-definitions/#enum-enum_field_types
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

MYSQL_TIME

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

Type	Member	Description
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	Time type

MARIADB_X509_INFO

The MARIADB_X509_INFO structure contains information about the peer certificate. This information is only available for TLS/SSL connections.

Type	Member	Description
int	version	Peer certificate version
char *	issuer	Issuer of peer certificate
char *	subject	Subject of peer certificate
char *	fingerprint	Fingerprint (SHA256, 384 or 512)
struct tm	notBefore	Start date of peer certificate
struct tm	notAfter	Expiration date of peer certificate

MARIADB_X509_INFO was added in MariaDB Connector/C 3.4.1