Which of the following is the valid syntax for adding a PRIMARY KEY constraint to an existing table? ( refer to the tables in the JustLee Books database). a. ALTER TABLE tablename ADD CONSTRAINT PRIMARY KEY (columnname); b. ALTER TABLE tablename ADD CONSTRAINT (columnname) PRIMARY KEY constraintname; c. ALTER TABLE tablename ADD [CONSTRAINT constraintname] PRIMARY KEY; d. None of the above is valid syntax.
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Which of the following is the valid syntax for adding a PRIMARY KEY constraint to an existing table? ( refer to the tables in the JustLee Books
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