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




MYSQL_FIELD

typedef struct st_mysql_field {
    char *name;         /* Name of column */
    char *org_name;     /* Name of original column (added after 3.23.58) */
    char *table;            /* Table of column if column was a field */
    char *org_table;        /* Name of original table (added after 3.23.58 */
    char *db;                     /* table schema (added after 3.23.58) */
    char *catalog;                /* table catalog (added after 3.23.58) */
    char *def;          /* Default value (set by mysql_list_fields) */
    unsigned long length;       /* Width of column */
    unsigned long max_length;   /* Max width of selected set */
  /* added after 3.23.58 */
    unsigned int name_length;
    unsigned int org_name_length;
    unsigned int table_length;
    unsigned int org_table_length;
    unsigned int db_length;
    unsigned int catalog_length;
    unsigned int def_length;
  /***********************/
    unsigned int flags;     /* Div flags */
    unsigned int decimals;  /* Number of decimals in field */
    unsigned int charsetnr;       /* char set number (added in 4.1) */
    enum enum_field_types type; /* Type of field. Se mysql_com.h for types */
    void *extension;              /* added in 4.1 */
  } MYSQL_FIELD;