SQLÉú³ÉËæ»ú×Ö·û´®
declare @str varchar(50)
declare @i int
set @str = ''
set @i=0
while @i<50
begin
set @str = @str + char(33 + cast(ceiling(rand() * 80) as int))
set @i = @i+1
end
select @str
Ïà¹ØÎĵµ£º
--²âÊÔÊý¾Ý
if OBJECT_ID('tb') is not null
drop table tb
go
CREATE TABLE tb(ID char(3),PID char(3),Name nvarchar(10))
INSERT tb SELECT '001',NULL ,'ɽ¶«Ê¡'
UNION ALL SELECT '002','001','ÑĮ̀ÊÐ'
UNION ALL SELECT '004','002','ÕÐÔ¶ÊÐ'
UNION ALL SELECT '003','001','ÇൺÊÐ'
UNION ALL SELECT '00 ......
ÔÚÒ»¸öÊý¾Ý±íÀÓÐ3¸ö×ֶΣ¬ÈçÏ£º
ID ×Ô¶¯Ôö¼Ó£¬Òѽ¨Ë÷Òý
TITLE nvarchar(255)
CONTENT ntext(16)
¶Ôtitle×ֶνøÐГlike”²éѯ£¬ËÙ¶È»¹ÐС£µ«ÊÇÒª¶Ôcontent×ֶΣ¬½øÐГlike”²éѯ£¬ËٶȺÜÂý£¬²»¿É ......
http://www.sql-server-performance.com/tips/clustered_indexes_p1.aspx
As a rule of thumb, every table should have a clustered index. Generally, but not always, the clustered index should be on a column that monotonically increases--such as an identity column, or some other column where the value is ......
1¡¢ÏÂÔØ±Ø±¸Èí¼þ
(1) JDK (Java Development Kit)
SUN¹Ù·½µÄÏÂÔØµØÖ·ÊÇhttp://java.sun.com/javase/downloads/index.jsp
(2) JDBC
(3) Eclipse
(4) Microsoft SQL Server 2005 Express£¨µ±È»£¬ÓзÇExpressÒ²OK°¡£©
(5) SQL Server Management Studio
2¡¢°²×°Óë»·¾³ÅäÖÃ
(1) JDK
Ê×ÏÈÔÚWindows»·¾³Ï£¬ÏÂÔØºó° ......
1.×Ö·û´®º¯Êý
³¤¶ÈÓë·ÖÎöÓÃ
datalength(Char_expr) ·µ»Ø×Ö·û´®°üº¬×Ö·ûÊý,µ«²»°üº¬ºóÃæµÄ¿Õ¸ñ
substring(expression,start,length) ²»¶à˵ÁË,È¡×Ó´®
right(char_expr,int_expr) ·µ»Ø×Ö·û´®ÓÒ±ßint_expr¸ö×Ö·û
×Ö·û²Ù×÷Àà
upper(char_expr) תΪ´óд
lower(char_expr) תΪСд
space(int_expr) Éú³Éint_expr¸ö¿Õ¸ñ ......