2. specify the firstEp and the secondEp in the configuration file taos.cfg
```shell
# first fully qualified domain name (FQDN) for TDengine system
firstEp cluster_node1:6030
```shell
# first fully qualified domain name (FQDN) for TDengine system
firstEp cluster_node1:6030
# second fully qualified domain name (FQDN) for TDengine system, for cluster only
secondEp cluster_node2:6030
# second fully qualified domain name (FQDN) for TDengine system, for cluster only
secondEp cluster_node2:6030
# default system charset
# charset UTF-8
# default system charset
# charset UTF-8
# system locale
# locale en_US.UTF-8
```
# system locale
# locale en_US.UTF-8
```
In the above example, JDBC uses the client's configuration file to establish a connection to a hostname `cluster_node1`, port 6030, and a database named `test`. When the firstEp node in the cluster fails, JDBC attempts to connect to the cluster using secondEp.
tdSql.query("SELECT _wstart,model,fleet,count(ms1)/144 FROM (SELECT _wstart as ts1,model, fleet,avg(status) AS ms1 FROM diagnostics WHERE ts >= '2016-01-01T00:00:00Z' AND ts < '2016-01-05T00:00:01Z' partition by model, fleet interval(10m) fill(value,0)) WHERE ts1 >= '2016-01-01T00:00:00Z' AND ts1 < '2016-01-05T00:00:01Z' AND ms1<1 partition by model, fleet interval(1d) ;")
tdSql.query("SELECT _wstart,model,fleet,count(ms1)/144 FROM (SELECT _wstart as ts1,model, fleet,avg(status) AS ms1 FROM diagnostics WHERE ts >= '2016-01-01T00:00:00Z' AND ts < '2016-01-05T00:00:01Z' partition by model, fleet interval(10m) ) WHERE ts1 >= '2016-01-01T00:00:00Z' AND ts1 < '2016-01-05T00:00:01Z' AND ms1<1 partition by model, fleet interval(1d) ;")
# 9. breakdown-frequency
# NULL ---count(NULL)=0 expect count(NULL)= 100
tdSql.query("SELECT model,state_changed,count(state_changed) FROM (SELECT model,diff(broken_down) AS state_changed FROM (SELECT _wstart,model,cast(cast(floor(2*(sum(nzs)/count(nzs))) as bool) as int) AS broken_down FROM (SELECT ts,model, cast(cast(status as bool) as int) AS nzs FROM diagnostics WHERE ts >= '2016-01-01T00:00:00Z' AND ts < '2016-01-05T00:00:01Z' ) WHERE ts >= '2016-01-01T00:00:00Z' AND ts < '2016-01-05T00:00:01Z' partition BY model interval(10m)) partition BY model) where model is null partition BY model,state_changed ")
parRows=tdSql.queryRows
assertparRows!=0,"query result is wrong"
tdSql.query(" SELECT model,state_changed,count(state_changed) FROM (SELECT model,diff(broken_down) AS state_changed FROM (SELECT _wstart,model,cast(cast(floor(2*(sum(nzs)/count(nzs))) as bool) as int) AS broken_down FROM (SELECT ts,model, cast(cast(status as bool) as int) AS nzs FROM diagnostics WHERE ts >= '2016-01-01T00:00:00Z' AND ts < '2016-01-05T00:00:01Z' ) WHERE ts >= '2016-01-01T00:00:00Z' AND ts < '2016-01-05T00:00:01Z' partition BY model interval(10m)) partition BY model) where state_changed =1 partition BY model,state_changed ;")