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create table tablename(id number primary key not null,column1 varchar2(),column2 varchar2(),column3 varchar2());

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alter table tablename modify [×Ö¶ÎÃû³Æ] [Êý¾ÝÀàÐÍ];

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alter table tablename rename column [ÐÞ¸Ä×Ö¶ÎÃû³Æ] to [ÐÞ¸Äºó×Ö¶ÎÃû³Æ];

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alter table tablename add [×Ö¶ÎÃû³Æ] [×Ö¶ÎÀàÐÍ]

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alter table tablename drop column [×Ö¶ÎÃû³Æ]

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select * from tablename

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insert into tablename(×Ö¶Î1£¬×Ö¶Î2£¬×Ö¶Î3) values(Êý¾Ý1£¬Êý¾Ý2£¬Êý¾Ý3);

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delete from tablename where Ìõ¼þÓï¾ä

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select * from tablename where rownum <= 10; //Õ¹Ê¾10ÌìÊý¾Ý

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select * from tablename where column1 like ¡®%xxx%¡¯; ²éÑ¯×Ö¶Îcolumn1 ÖÐ°üº¬xxx×Ö·û´®µÄÊý¾Ý

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select * from tablename where column1 between [Êý¾Ý1] and [Êý¾Ý2];

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LEFT JOIN ¹Ø¼ü×Ö»á´Ó×ó±í (Persons) ÄÇÀï·µ»ØËùÓÐµÄÐÐ£¬¼´Ê¹ÔÚÓÒ±í (Orders) ÖÐÃ»ÓÐÆ¥ÅäµÄÐÐ¡£

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SELECT E_Name FROM Employees_China
UNION
SELECT E_Name FROM Employees_USA

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insert into Employees_China select * from Employees_USA;

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CREATE TABLE Persons
(
Id_P int NOT NULL CHECK (Id_P>0),
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255)
)
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ALTER TABLE Persons
ADD CHECK (Id_P>0)

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 CREATE TABLE Persons
(
Id_P int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255) DEFAULT 'Sandnes'
)
³·ÏúDEFAULT·½·¨
ALTER TABLE Persons
MODIFY City  DEFAULT NULL
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CREATE INDEX PersonIndex
ON Person (LastName) 

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DROP INDEX index_name

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CREATE VIEW view_name AS
SELECT column_name(s)
FROM table_name
WHERE condition

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insert into tablename(id,createdate) values(1,sysdate); //²åÈëÏµÍ³Ê±¼ä

insert into tablename(id,createdate) values(1,to_date('2015-03-11 16:03:10','yyyy-MM-dd HH24:mi:ss'));//²åÈëÏàÓ¦¸ñÊ½Êý¾ÝµÄÈÕÆÚ

select to_char(createdate,'yyyy-MM-dd HH24:mi:ss') from tablename; //ÈÕÆÚÊä³öÕ¹Ê¾

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