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What type of constraint is used to ensure that each row inserted into the EMPLOYEE table with a value in the WORKDEPT column has a row with a corresponding value in the DEPTNO column of the DEPARTMENT table?()
A check constraint on the EMPLOYEE table
B. A unique constraint on the EMPLOYEE table WORKDEPT column
C. A foreign key reference from the DEPARTMENT tables DEPTNO column to the WORKDEPT column of the EMPLOYEE table
D. A foreign key reference from the EMPLOYEE tables WORKDEPT column to the DEPTNO column of the DEPARTMENT table
Fe2O3为()氧化物。
A. 碱性
B. 中性
C. 酸性
离心泵调节进口流量容易造成气蚀而损坏泵。
A. 正确
B. 错误