, Database Engine . Microsoft SQL Server - : .
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CREATE TABLE test_defaults
(date_ins datetime DEFAULT getdate(), --Preferred default definition
mathcol smallint DEFAULT 10 * 2, --Preferred default definition
char2 char(3) DEFAULT 'xyz') --Preferred default definition;
NOT NULL
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CREATE TABLE cust_sample
(
cust_id int PRIMARY KEY,
cust_name char(50),
cust_address char(50),
cust_credit_limit money,
CONSTRAINT chk_id CHECK (cust_id BETWEEN 0 and 10000)
)
UNIQUE
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UNIQUE . NULL ( UNIQUE, NULL ).
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PRIMARY KEY , , PRIMARY KEY .
, vendorID vendorPartID complexPartTable PRIMARY KEY . vendorID vendorPartID.
NULL .
PRIMARY KEY . . . , , , NONCLUSTERED.
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UNIQUE PRIMARY KEY , , , , PRIMARY KEY UNIQUE.
partTable partId . , partId , .
CREATE TABLE partTable
(partId int PRIMARY KEY NONCLUSTERED,
name char(30),
weight decimal(6,2),
color char(15));
FOREIGN KEY
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SET DEFAULT: , , .
ON UPDATE , , . NO ACTION, CASCADE, SET NULL SET DEFAULT.
