1.查询张表中某个字段大值:SELECTMAX(column_name)FROMtable_name;
2.查询张表中某个字段小值:SELECTMIN(column_name)FROMtable_name;
3.查询张表中某个字段平均值:SELECTAVG(column_name)FROMtable_name;
4.查询张表中某个字段求和值:SELECTSUM(column_name)FROMtable_name;
5.查询张表中某个字段有不重复值:SELECTDISTINCTcolumn_nameFROMtable_name;
6.查询张表中某几个字段和/平均值/大值等:SELECTSUM(column_name1),AVG(column_name2),MAX(column_name3)FROMtable_name;
7.查询张表中某个字段符合某个条件记录数量:SELECTCOUNT()FROMtable_nameWHEREcolumn_name>10;