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create database test --½¨Á¢testÊý¾Ý¿â
use test
create table BONUS --½¨Á¢
(
ENAME NVARCHAR(10),
JOB NVARCHAR(9),
SAL FLOAT,
COMM FLOAT
)
create table DEPT --½¨Á¢²¿Ãűí
(
DEPTNO SMALLINT not null, --²¿ÃűàºÅ
DNAME NVARCHAR(14), --²¿ÃÅÃû
LOC NVARCHAR(13), --³ÇÊÐ
primary key (DEPTNO)
)
;
create table EMP --½¨Á¢Ô±¹¤±í
(
EMPNO SMALLINT not null, --Ô±¹¤±àºÅ
ENAME NVARCHAR(10), --Ô±¹¤ÐÕÃû
JOB NVARCHAR(9), --¸Úλ
MGR SMALLINT, --¾­Àí
HIREDATE DATETIME, --¹ÍÓ¶ÈÕÆÚ
SAL FLOAT, --¹¤×Ê
COMM FLOAT, --ͨѶ·Ñ
DEPTNO SMALLINT, --²¿ÃűàºÅ
primary key (EMPNO),
foreign key (DEPTNO) references DEPT (DEPTNO)
)
;
create table SALGRADE --Ô±¹¤¼¶±ð
(
GRADE SMALLINT, --µÈ¼¶
LOSAL SMALLINT, --×îµÍ¹¤×Ê
HISAL SMALLINT --×î¸ß¹¤×Ê
)
;
insert into DEPT (DEPTNO, DNAME, LOC)
values (10, 'ACCOUNTING', 'NEW YORK');
insert into DEPT (DEPTNO, DNAME, LOC)
values (20, 'RESEARCH', 'DALLAS');
insert into DEPT (DEPTNO, DNAME, LOC)
values (30, 'SALES', 'CHICAGO');
insert into DEPT (DEPTNO, DNAME, LOC)
values (40, 'OPERATIONS', 'BOSTON');
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7369, 'SMITH', 'CLERK', 7902, '1980-12-17', 800, null, 20);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7499, 'ALLEN', 'SALESMAN', 7698, '1981-02-20', 1600, 300, 30);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7521, 'WARD', 'SALESMAN', 7698, '1981-02-22', 1250, 500, 30);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7566, 'JONES', 'MANAGER', 7839, '1981-4-2', 2975, null, 20);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7654, 'MARTIN', 'SALESMAN', 7698, '1981-9-28', 1250, 1400, 30);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7698,


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declare @i int
set @i=1
while @i<101
begin
insert into Cname ([name],csex,Number) ......

sqlÓï¾ä

select *from student
select student_id from student
select student_id ,student_name from student
select student_id student_name from student  ½«student_name ×÷Ϊstudent_idµÄ±ðÃû´¦Àí
È磺   select student_id a from student
 select a=student_id from student
´Óstudent±íÖзֱð¼ ......

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/*
Ô­±í£º  
thid      other  
a              1  
a              1  
b              0  
b              0  
......

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countÓï¾äÖ§³Ö*¡¢ÁÐÃû¡¢³£Á¿¡¢±äÁ¿,²¢ÇÒ¿ÉÒÔÓÃdistinct¹Ø¼ü×ÖÐÞÊΣ¬ ²¢ÇÒcount(ÁÐÃû)²»»áÀÛ¼ÆnullµÄ¼Ç¼¡£ÏÂÃæËæ±ãÓÃһЩÀý×Óʾ·¶Ò»ÏÂcountµÄ¹æÔò£º±ÈÈç¶ÔÈçϱí×öͳ¼Æ£¬ËùÓÐÁÐÕâÀï¶¼ÓÃsql_variantÀàÐÍÀ´±íʾ¡£
if (object_id ('t_test' )> 0 )
    drop table t_test
go
create table t_test (a ......
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