MySQL 5.6 C API Developer Guide
int mysql_options4(MYSQL *mysql, enum mysql_option option, const void *arg1, const void *arg2)
mysql_options4()
is similar to
mysql_options()
but has an
extra fourth argument so that two values can be passed for the
option specified in the second argument.
The following list describes the permitted options, their
effect, and how arg1
and
arg2
are used.
MYSQL_OPT_CONNECT_ATTR_ADD
(argument
types: char *, char *
)
This option adds an attribute key-value pair to the current set of connection attributes to pass to the server at connect time. Both arguments are pointers to null-terminated strings. The first and second strings indicate the key and value, respectively. If the key is empty or already exists in the current set of connection attributes, an error occurs. Comparison of the key name with existing keys is case-sensitive.
Key names that begin with an underscore
(_
) are reserved for internal use and
should not be created by application programs. This
convention permits new attributes to be introduced by
MySQL without colliding with application attributes.
mysql_options4()
imposes a
limit of 64KB on the aggregate size of connection
attribute data it will accept. For calls that cause this
limit to be exceeded, a
CR_INVALID_PARAMETER_NO
error occurs. Attribute size-limit checks also occur on
the server side. For details, see
Performance Schema Connection Attribute Tables,
which also describes how the Performance Schema exposes
connection attributes through the
session_connect_attrs
and
session_account_connect_attrs
tables.
See also the descriptions for the
MYSQL_OPT_CONNECT_ATTR_RESET
and
MYSQL_OPT_CONNECT_ATTR_DELETE
options
in the description of the
mysql_options()
function.
A duplicate attribute name was specified.
A key name was empty or the amount of key-value connection attribute data exceeds 64KB limit.
Out of memory.
This example demonstrates the calls that specify connection attributes:
MYSQL mysql;
mysql_init(&mysql);
mysql_options(&mysql,MYSQL_OPT_CONNECT_ATTR_RESET, 0);
mysql_options4(&mysql,MYSQL_OPT_CONNECT_ATTR_ADD, "key1", "value1");
mysql_options4(&mysql,MYSQL_OPT_CONNECT_ATTR_ADD, "key2", "value2");
mysql_options4(&mysql,MYSQL_OPT_CONNECT_ATTR_ADD, "key3", "value3");
mysql_options(&mysql,MYSQL_OPT_CONNECT_ATTR_DELETE, "key1");
if (!mysql_real_connect(&mysql,"host","user","passwd
","database",0,NULL,0))
{
fprintf(stderr, "Failed to connect to database: Error: %s\n",
mysql_error(&mysql));
}