Querying ClickHouse Data

Function Description

Query statement 1: querySql1 queries random 10 records in the tableName table.

Query statement 2: querySql2 uses a built-in function to obtain the year and month from the date field in the tableName table and then aggregate the data.

Sample Code

private void queryData(String databaseName, String tableName) throws Exception {
     String querySql1 = "select * from " + databaseName + "." + tableName + "_all" + " order by age limit 10";
     String querySql2 = "select toYYYYMM(date),count(1) from " + databaseName + "." + tableName + "_all" + " group by toYYYYMM(date) order by count(1) DESC limit 10";
     ArrayList<String> sqlList = new ArrayList<String>();
     sqlList.add(querySql1);
     sqlList.add(querySql2);
     ArrayList<ArrayList<ArrayList<String>>> result = util.exeSql(sqlList);
     for (ArrayList<ArrayList<String>> singleResult : result) {
         for (ArrayList<String> strings : singleResult) {
             StringBuilder stringBuilder = new StringBuilder();
             for (String string : strings) {
                 stringBuilder.append(string).append("\t");
             }
             log.info(stringBuilder.toString());
         }
     }
 }