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（ 25 ）假设有 student 表，可以正确添加字段 “ 平均分数 ” 的命令是
A ） ALTER TABLE student ADD 平均分数 F(6,2)
B ） ALTER DBF student ADD 平均分数 F 6,2
C ） CHANGE TABLE student ADD 平均分数 F(6,2)
D ） CHANGE TABLE student INSERT 平均分数 6,2
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更多 “ （ 25 ）假设有 student 表，可以正确添加字段 “ 平均分数 ” 的命令是A ） ALTER TABLE student ADD 平均分数 F(6,2)B ） ALTER DBF student ADD 平均分数 F 6,2C ） CHANGE TABLE student ADD 平均分数 F(6,2)D ） CHANGE TABLE student INSERT 平均分数 6,2 ” 相关考题
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You need to modify the STUDENTS table to add a primary key on the STUDENT_ID column. The table is currently empty.Which statement accomplishes this task?（）A、ALTER TABLE students ADD PRIMARY KEY student_id;B、ALTER TABLE students ADD CONSTRAINT PRIMARY KEY (student_id);C、ALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY student_id;D、ALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY (student_id);E、ALTER TABLE students MODIFY CONSTRAINT stud_id_pk PRIMARY KEY (student_id);
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单选题假设有student表，可以正确添加字段“平均分数”的命令是（ ）。A
ALTER TABLE student ADD平均分数F(6,2)B
ALTER DBF student ADD平均分数F6，2C
CHANGE TABLE student ADD平均分数F(6,2)D
CHANGE TABLE student INSERT平均分数6，2
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单选题给student表增加一个“平均成绩”字段(数值型，总宽度6，2位小数)的SQL命令是（ ）。A
ALTER TABLE student ADD平均成绩N(6，2)B
ALTER TABLE student ADD平均成绩D(6，2)C
ALTER TABLE student ADD平均成绩E(6，2)D
ALTER TABLE student ADD平均成绩Y(6，2)
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单选题删除student表的“平均成绩”字段的正确SQL命令是（ ）。A
DELETE TABLE student DELETE COLUMN平均成绩B
ALTER TABLE student DELETE COLUMN平均成绩C
ALTER TABLE student DROP COLUMN平均成绩D
DELETE TABLE student DROP COLUMN平均成绩
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