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 C0LUMN平均成绩

C．ALTER TABLE student DROP COLUMN平均成绩

D．DELETE TABLE student DROP COLUMN平均成绩

[单选题]删除student表的“平均成绩”字段的正确SQL命令是（　　）。A.DELETETABLEstudentDELETECOLUMN平均成绩B.ALTE

[单选题]删除student表中“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

[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.ALTERTABLEstudentADD平均成绩N

[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.ALTERTABLEstudentADD平均成绩N

[单选题]从student表删除年龄大于30的记录的正确SQL命令是A．DELETE FOR年龄>30B．DELETE FROM student WHERE年龄>30C．DELETE student FOR年龄>30D．DELETE student WHERE年龄>30

[单选题]从student表删除年龄大于30的记录的正确SQL命令是（　　）。A.DELETEFOR年龄>30B.DELETEFROMstudentWHERE年

[单选题]从student表删除年龄大于30的记录的正确SQL命令是（ ）。A． DELETE FOR年龄>30B． DELETE FROM student WHERE年龄>30C． DELETE student FOR年龄>30D． DELETE student WHERE年龄>30

[单选题]从student表删除年龄大于30的记录的正确SQL命令是（ ）。A． DELETE FOR年龄>30B． DELETE FROM student WHERE年龄>30C． DELETE student FOR年龄>30D． DELETE student WHERE年龄>30

[单选题]删除表s中字段c的SQL命令是（　　）。A.ALTERTABLEsDELEDEcB.ALTERTABLEsDROPcC.DELETETABLEsDEL

[单选题]删除表s中字段c的SQL命令是A．ALTER TABLE s DELETE cB．ALTER TABLE s DROP cC．DELETE TABLE s DELETE cD．DELETE TABLE s DROP c