单项选择题
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.
相关考题
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单项选择题
An application needs to store a 5 MB JPEG image in a DB2 table. Which data type should be specified for the column that will be used for storing the image?（）
A.GRAPHIC
B.BINARY
C.IMAGE
D.BLOB -
单项选择题
Given the following requirements: Create a table to contain employee data, with a unique numeric identifier automatically assigned when a row is added, has an EDLEVEL column that permits only the values C, H and N, and permits inserts only when a corresponding value for the employees department exists in the DEPARTMENT table. Which of the following CREATE statements will successfully create this table?（）
A.CREATE TABLE emp ( empno SMALLINT NEXTVAL GENERATED ALWAYS AS IDENTITY, firstname VARCHAR(30) NOT NULL, lastname VARCHAR(30) NOT NULL, workdept CHAR(3) NOT NULL, edlevel CHAR(1), PRIMARY KEY emp_pk (empno), FOREIGN KEY emp_workdept_fk ON (workdept) REFERENCES department (deptno), CHECK edlevel_ck VALUES (edlevel IN ('C','H','N')), );
B.CREATE TABLE emp ( empno SMALLINT NOT NULL GENERATED BY DEFAULT AS IDENTITY, firstname VARCHAR(30) NOT NULL, lastname VARCHAR(30) NOT NULL, workdept CHAR(3), edlevel CHAR(1), CONSTRAINT emp_pk PRIMARY KEY (empno), CONSTRAINT emp_workdept_fk FOREIGN KEY (workdept) REFERENCES department (deptno), CONSTRAINT edlevel_ck CHECK edlevel VALUES ('C','H','N') );
C.CREATE TABLE emp ( empno SMALLINT NEXTVAL GENERATED BY DEFAULT AS IDENTITY, firstname VARCHAR(30) NOT NULL, lastname VARCHAR(30) NOT NULL, workdept CHAR(3) NOT NULL, edlevel CHAR(1) CHECK IN ('C','H','N')), CONSTRAINT emp_pk PRIMARY KEY (empno), CONSTRAINT emp_workdept_fk FOREIGN KEY department (deptno) REFERENCES (workdept) );
D.CREATE TABLE emp ( empno SMALLINT NOT NULL GENERATED BY DEFAULT AS IDENTITY, firstname VARCHAR(30) NOT NULL, lastname VARCHAR(30) NOT NULL, workdept CHAR(3), edlevel CHAR(1), CONSTRAINT emp_pk PRIMARY KEY (empno), CONSTRAINT emp_workdept_fk FOREIGN KEY (workdept) REFERENCES department (deptno), CONSTRAINT edlevel_ck CHECK (edlevel IN ('C','H','N')) ); -
单项选择题
When defining a referential constraint between the parent table T2 and the dependent table T1, which of the following is true?（）
A.The list of column names in the FOREIGN KEY clause can be a subset of the list of column names in the primary key of T2 or a UNIQUE constraint that exists on T2.
B.The list of column names in the FOREIGN KEY clause can be a subset of the list of column names in the primary key of T1 or a UNIQUE constraint that exists on T1.
C.The list of column names in the FOREIGN KEY clause must be identical to the list of column names in the primary key of T2 or a UNIQUE constraint that exists on T2.
D.The list of column names in the FOREIGN KEY clause must be identical to the list of column names in the primary key of T1 or a UNIQUE constraint that exists on T1.
