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. This function was added in
MySQL 5.6.6.
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
Section 22.10.8, “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
MYSQL_OPT_CONNECT_ATTR_DELETE options in
the description of the
mysql_options() function.
Zero for success. Nonzero if you specify an unknown option.
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));
}