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  • 添加约束及打印五角星及查询

      1 USE MySchool
      2 --添加主键约束
      3 alter table Student 
      4 add constraint PK_StudentNo primary key (StudentNo)
      5 
      6 
      7 --添加唯一约束
      8 alter table Student
      9 add constraint UQ_IdentityCard unique (IdentityCard)
     10 
     11 
     12 --添加默认约束
     13 alter table Student
     14 add constraint DF_Address default('地址不详') for Address
     15 
     16 --添加检查约束
     17 alter table Student
     18 add constraint CK_BornDate check (BornDate>='1980-01-01')
     19 
     20 
     21 --添加外键约束
     22 alter table Student
     23 add constraint FK_StudentNO foreign key(StudentNo) references Student(StudentNo)
     24 
     25 declare @x int ,@a int,@z varchar(100),@y nvarchar
     26 set @x =0
     27 set @a=5
     28 set @y=''
     29 set @z=''
     30 while @x<5
     31 begin
     32 set @x=@x+1
     33 set @a=@a-1
     34 set @z=REPLICATE (@y,@x)+REPLICATE('',@a)
     35 print @z
     36 end
     37 
     38 
     39 --求符合条件的人数
     40 --if me ,I'll do this 
     41 --01.定义一个int类型的变量,保存课程名称为"oop"对应的课程编号
     42 --declare @subid int
     43 --select @subid=subjectid
     44 --from Subject
     45 --where SubjectName='oop'
     46 --print @subid
     47 
     48 
     49 
     50 declare @subid int 
     51 select @subid =subjectid
     52 from Subject
     53 where SubjectName='oop'
     54 declare @Maxdate datetime
     55 select @Maxdate=MAX(examdate)
     56 from Result
     57 where SubjectId=@subid
     58 declare @totaCount int
     59 select @totaCount=COUNT (*)
     60 from Result
     61 where SubjectId=@subid
     62 and ExamDate =@Maxdate
     63 and StudentResult<80
     64 
     65 
     66 
     67 select @totalCount=COUNT(*) 
     68 from Result
     69 where SubjectId=@subid
     70 and ExamDate=@Maxdate
     71 and StudentResult<80
     72 
     73 
     74 
     75 
     76 
     77 
     78 --02.第二个限定条件   最近一次  携带  课程编号
     79 --max() min() sum() count() avg()
     80 --定义一个Datetime类型的变量,保存最近一次考试时间
     81 declare @Maxdate datetime
     82 select @Maxdate=MAX(examdate) 
     83 from Result
     84 where SubjectId=@subid
     85 
     86 --select * from Result
     87 
     88 --easy  总人数
     89 --03.定义一个保存总人数的变量
     90 declare @totalCount int
     91 
     92 
     93 
     94 select @totalCount=COUNT(*) 
     95 from Result
     96 where SubjectId=@subid
     97 and ExamDate=@Maxdate
     98 and StudentResult<80
     99 
    100 --56   
    101 --判定人数>0
    102 
    103 --循环
    104 while(@totalCount>0)
    105 begin
    106    --有不及格的,提分+2  高于95,不提
    107    update Result set StudentResult=StudentResult+2
    108    where  SubjectId=@subid
    109     and ExamDate=@Maxdate
    110     and StudentResult<95
    111     
    112     select @totalCount=COUNT(*) 
    113 from Result
    114 where SubjectId=@subid
    115 and ExamDate=@Maxdate
    116 and StudentResult<80
    117     
    118     
    119 
    120 end
    121 
    122 
    123 
    124 
    125 
    126 
    127 
    128 
    129 
    130 
    131 
    132 --代码
    133 
    134 declare @subid int
    135 select @subid =subjectID from Subject
    136 where SubjectName='oop'
    137 declare @examDate datetime
    138 select @examDate=MAX(examdate)from
    139 Result where SubjectId=@subid
    140 
    141 declare @num int
    142 select @num=COUNT(*)from Result
    143 where SubjectId =@subid 
    144 and ExamDate=@examDate
    145 and StudentResult<60
    146 while (@num>0)
    147 begin
    148 update Result
    149 set StudentResult+=2
    150 where SubjectId=@subid and ExamDate=@examDate
    151 and StudentResult<95
    152 select @num=count(*)from Result
    153 where subjectid =@subid 
    154 and ExamDate=@examDate 
    155 and studentResult<60
    156 end
    157 
    158 
    159 --查询学生姓名和成绩
    160 declare @subid int
    161 select @subid=subjectid
    162 from Subject
    163 where SubjectName='oop'
    164 declare @Maxdate datetime
    165 select @Maxdate=MAX(examdate) 
    166 from Result
    167 where SubjectId=@subid
    168 case
    169 where SubjectResult>=90 then  'A'
    170 where SubjectResult>=80 then  'B'
    171 where SubjectResult>=70 then  'C'
    172 where SubjectResult>=60 then  'D'
    173 else 'E'
    174 
    175 
    176 end
    177 from Result ,subject
    178 where result.subjectId=subject.subjectId
    179 and subjectName
    180  
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  • 原文地址:https://www.cnblogs.com/WuXuanKun/p/5361223.html
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