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mysql_real_connect_dns_srv() is similar tomysql_real_connect(), except that the argument list does not specify the particular host of the MySQL server to connect to. Instead, it names a DNS SRV record that specifies a group of servers. For information about DNS SRV support in MySQL, seeConnecting to the Server Using DNS SRV Records.

Thedns_srv_name argument formysql_real_connect_dns_srv() takes the place of thehost,port, andunix_socket arguments formysql_real_connect(). Thedns_srv_name argument names a DNS SRV record that determines the candidate hosts to use for establishing a connection to a MySQL server.

Themysql,user,passwd,db, andclient_flag arguments tomysql_real_connect_dns_srv() have the same meanings as formysql_real_connect(). For descriptions of their meanings, seeSection 5.4.58, “mysql_real_connect()”.

Suppose that DNS is configured with this SRV information for theexample.com domain:

Name                     TTL   Class   Priority Weight Port Target_mysql._tcp.example.com. 86400 IN SRV  0        5      3306 host1.example.com_mysql._tcp.example.com. 86400 IN SRV  0        10     3306 host2.example.com_mysql._tcp.example.com. 86400 IN SRV  10       5      3306 host3.example.com_mysql._tcp.example.com. 86400 IN SRV  20       5      3306 host4.example.com

To use that DNS SRV record, pass"_mysql._tcp.example.com" as thedns_srv_name argument tomysql_real_connect_dns_srv(), which then attempts a connection to each server in the group until a successful connection is established. A failure to connect occurs only if a connection cannot be established to any of the servers. The priority and weight values in the DNS SRV record determine the order in which servers should be tried.

mysql_real_connect_dns_srv() attempts to establish TCP connections only.

The client library performs a DNS SRV lookup for each call tomysql_real_connect_dns_srv(). The client library does no caching of lookup results.

AMYSQL* connection handler if the connection was successful,NULL if the connection was unsuccessful. For a successful connection, the return value is the same as the value of the first argument.

The same that you can get frommysql_real_connect(), plus:

The following example uses the name of the DNS SRV record shown previously as the source of candidate servers for establishing a connection.

MYSQL mysql;const char *dns_srv_name = "_mysql._tcp.example.com";mysql_init(&mysql);if (!mysql_real_connect_dns_srv(&mysql,dns_srv_name,"user","passwd","database",0)){    fprintf(stderr, "Failed to connect to database: Error: %s\n",          mysql_error(&mysql));}