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CREATE TABLE MISSION
(
ID INT,
NAME VARCHAR(225),
MISSIONTYPE_ID INT,
COMMON_NAME VARCHAR(225),
FILE_NAME VARCHAR(225),
AMOUNT INT,
ACCEPT_DATE DATE, ½ÓÊÕÈÕÆÚ
DELIVERY_DATE DATE, ½»»õÈÕÆÚ
MEMO TEXT,

PRIMARY KEY(ID),
)DEFAULT CHARSET=UTF8;


--¹¤×÷½ø¶È--
CREATE TABLE MISSIONDE
(
ID INT,
EMPLOYEE_ID INT,
TODAY DATE, £¨Ã¿ÌìÈÕÆÚ£©
MISSION_ID INT,
WORKTYPE_ID INT,
AMOUNT INT,
MISS_AMOUNT INT,
MEMO TEXT,

FOREIGN KEY(MISSION_ID) REFERENCES MISSION(ID)
)DEFAULT CHARSET=UTF8;


¸ù¾Ý ±íMISSION£¨¹¤×÷ÒªÇóµÄ£©
ACCEPT_DATE DATE      2009-09-10
DELIVERY_DATE DATE,  2010-01-20

ÏÔʾ±íMISSIONDE µÄTODAY  TODAYûÓÐÊý¾Ý ÏÔʾnull
2009-09-10  MISSIONDE.id 
2009-09-11    .
2009-09-12    .
2009-09-13    .
2009-09-14    .
¡£
¡£
¡£
2010-01-20  null 

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SQL code:
case when TODAY is null then null else MISSIONDE.id end

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SQL code

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Code