1 SQL AVG()
SQL AVG:函数返回数值列的平均值。NULL值不包括在计算中 SELECT AVG(withdrawal_amt) AS withdrawal_amtAverage FROM lambda.withdrawal_detail_info;
2 SQL Count()
Count ()语法：指函数返回指定列的值的数目、 SELECT Count(withdrawal_amt) FROM lambda.withdrawal_detail_info;
SELECT Count(DISTINCT withdrawal_amt) FROM lambda.withdrawal_detail_info; //用于返回指定列的不同值的数目+
3SQL First/SQL LAST/SQL MAX/SQL MIN/SQL SUM
SELECT MAX(withdrawal_amt) FROM lambda.withdrawal_detail_info;
SELECT SUM(withdrawal_amt) FROM lambda.withdrawal_detail_info;
4SQL GROUP BY语句
GROUP BY语句用于结合合计函数，根据一个或多个列对结果集进行分组 SELECT SUM(withdrawal_amt) FROM lambda.withdrawal_detail_info GROUP BY(withdrawal_status);
5SQL HAVING子句
SQL HAVING语法 HAVING语法可以与GroupBy一起使用
6SQL UCASE()/SQL LCASE()
SELECT UCASE(withdrawal_status) AS oNE FROM lambda.withdrawal_detail_info;
SELECT LCASE(withdrawal_status) AS oNE FROM lambda.withdrawal_detail_info;
7SQL MID()
选取字段 SELECT MID(withdrawal_status,2,5) as two FROM lambda.withdrawal_detail_info;
8 SQL LEN()
SQL LEN()语法 SELECT LEN(column_name) FROM table_name SELECT LENGTH(withdrawal_status) AS two FROM lambda.withdrawal_detail_info;
9 SQL ROUND()
SQL ROUND( column_name,decimals):ROUND函数用于把数值字段舍入位指定的小数位数 SELECT ROUND(penalty_rate) as three FROM lambda.withdrawal_detail_info;
