用最高效最简单的SQL列出各班成绩最高的列表（国外英文资料）.docVIP

用最高效最简单的SQL列出各班成绩最高的列表（国外英文资料） Table: table1 (FId, Fclass, Fscore), with the most efficient and simplest SQL list, lists the highest scores in each class, displaying the class, and the grades two fields. Select fclass, Max (fscore) from table1 group by fclass, fid There is a table table1 with two field FID, Fno, which is not empty, and writes an SQL statement to list the records of a single FID in the table for several different Fno. Such as: 101 a1001 101 a1001 102 a1002 102 a1003 103 a1004 104 a1005 104 a1006 105 a1007 105 a1007 105 a1007 Results: 102 a1002 102 a1003 104 a1005 104 a1006 Select t2. * from table1 t1, table1 t2 where t1. 3, have empinfo employees table ( Fempno varchar2 (10) not null pk, Fempname varchar2 (20) not null, Fage number not null, Fsalary number not null ); If the amount is about 10 million; Write a SQL that you think is the most efficient, and use one SQL to calculate the following four types of people: F salary 9999 and fage 35 F salary 9999 and fage 35 Salary 9999 and fage 35 Salary 9999 and fage 35 The number of employees; Select sum (case when fsalary 9999 and fage 35 Then 1 fsalary 9999_fage 35, Sum (case when fsalary 9999 and fage 35 Then 1 The else 0 End) as fsalary 9999_fage 35, Sum (case when fsalary 9999 and fage 35 Then 1 The else 0 End) as fsalary 9999_fage 35, Sum (case when fsalary 9999 and fage 35 Then 1 The else 0 End) as fsalary 9999_fage 35 The from empinfo; Table A fields are as follows The month person income Monthly income Requires an SQL statement (note that one is a) that someone (not a person) has total monthly and monthly gross income The list output is required Income from the month of the month Have the PERSON INCOME -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 200807 mantisXF mantisXF2 mantisXF3 mantisXF1 mantisXF6 mantisXF7 2200200804 2000200805 3000200805 3500200806 5000200806 1800200803 4000200802 9 mantisXF mantisXF 10 mantisXF 3300200801