单选题Which constraint can be defined only at the column level? （）A UNIQUEB NOT NULLC CHECKD PRIMARY KEYE FOREIGN KEY

相关问题 1：

Which constraint can be defined only at the column level? ()A. UNIQUEB. NOT NULLC. CHECKD. PRIMARY KEYE. FOREIGN KEY

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相关问题 2：

Which constraint can be defines only at the column level? ()A. UNIQUEB. NOT NULLC. CHECKD. PRIMARY KEYE. FOREIGN KEY

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相关问题 3：

Which of the following constraint types can be used to ensure the value of an INTEGER column references only positive values?()A.UniqueB.CheckC.ReferentialD.Informational

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相关问题 4：

Which of the following scenarios will ensure that the value of the NEXT_STEPNO column in a given row of table TABLEX exists as a value of column STEPNO (usually in another row) in the same table?()A.Define a UNIQUE constraint on the columns NEXT_STEPNO and STEPNO.B.Define a CHECK constraint on the NEXT_STEPNO column (NEXT_STEPNO = STEPNO).C.Define column STEPNO as the primary key of TABLEX and column NEXT_STEPNO as a foreign key referencing column STEPNO of the same table.D.Define column NEXT_STEPNO as the primary key of TABLEX and column STEPNO as a foreign key referencing column NEXT_STEPNO in the same table.

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相关问题 5：

Which of the following constraint types can be used to ensure the value of an INTEGER column references only positive values?（）A、UniqueB、CheckC、ReferentialD、Informational

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相关问题 6：

If a unique constraint is defined on column COL1 of table TAB1, what are the characteristics of COL1?（）A、COL1 will accept NULL values and can be referenced in another table's foreign key specification.B、COL1 will not accept NULL values and cannot be referenced in another tables foreign key specification.C、COL1 will not accept NULL values and can be referenced in another tables foreign key specification.D、COL1 will accept NULL values and cannot be referenced in another tables foreign key specification.

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相关问题 7：

Which of the following scenarios will ensure that the value of the NEXT_STEPNO column in a given row of table TABLEX exists as a value of column STEPNO (usually in another row) in the same table?（）A、Define a UNIQUE constraint on the columns NEXT_STEPNO and STEPNO.B、Define a CHECK constraint on the NEXT_STEPNO column (NEXT_STEPNO = STEPNO).C、Define column STEPNO as the primary key of TABLEX and column NEXT_STEPNO as a foreign key referencing column STEPNO of the same table.D、Define column NEXT_STEPNO as the primary key of TABLEX and column STEPNO as a foreign key referencing column NEXT_STEPNO in the same table.

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