Slide/SQL PRIMARY KEY

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• SQL-DDL-PrimaryKey

• SQL
• SQL Syntax
• PRIMARY KEY

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qkey	SQL-24
pkey	SQL
basename	4-RelationaleDatenbankspracheSQL.pptx
page	24
name	SQL_PRIMARY_KEY
title	PRIMARY KEY
keywords	SQL, SQL Syntax, PRIMARY KEY
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literature
learningGoal	lg/SQL-DDL-PrimaryKey→lg/SQL-DDL-PrimaryKey

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PRIMARY KEY
Die •PRIMARY KEY •Einschränkung ist äquivalent zu „•NOT NULL UNIQUE•“•Verschiedene Möglichkeiten zur Festlegung eines Primary Keys• •CREATE TABLE Kunde•( KName CHAR (20) NOT NULL UNIQUE, KAdr VARCHAR (50),•  Saldo DECIMAL (7) , •  •PRIMARY KEY (KName)•  )••oder• CREATE TABLE Kunde•(•KName• CHAR (20) NOT NULL UNIQUE •PRIMARY KEY•, KAdr VARCHAR (50), • Saldo DECIMAL (7) )••oder• CREATE TABLE Kunde•( KName CHAR (20) NOT NULL UNIQUE, KAdr VARCHAR (50), Saldo DECIMAL (7), •CONSTRAINT pk_kunde PRIMARY KEY (KName) •)