检索选修的至少一门课程的成绩高于或等于85分的学生的学号、姓名和性别,正确的SQL命令是()。
A. SELECT xh,xm,xb FROM xsxx WHERE EXIST ; (SELECT* FROM xscj WHERE xsxx.xh=xscj.xh AND cj<=85)
B. SELECT xh,xm,xb FROM xsxx WHERE NOT EXIST ; (SELECT* FROM xscj WHERE xsxx.xh=xscj.xh AND cj<=85)
C. SELECT xh,xm,xb FROM xsxx WHERE EXIST ; (SELECT* FROM xscj WHERE xsxx.xh=xscj.xh AND cj>=85)
D. SELECT xh,xm,xb FROM xsxx WHERE NOT EXIST ; (SELECT* FROM xscj WHERE xsxx.xh=xscj.xh AND cj<85) AND
假定学号的第11、12位为班级代码，要计算各班学生选修课程号为“410001”课程的平均成绩，正确的SQL命令是()。
A. SELECT SUBSTR(xh,11,2) AS 班级,AVG(cj) AS 平均分 FROM xscj; WHERE kch="410001" GROUP BY 1
B. SELECT 班级 AS SUBSTR(xh,11,2), 平均分 AS AVG(cj) FROM xscj; WHERE kch="410001" GROUP BY班级
C. SELECT SUBSTR(xh,11,2) AS 班级,AVG(cj) AS 平均分 FROM xscj; WHERE kch="410001" ORDER BY 1
D. SELECT 班级 AS SUBSTR(xh,11,2), 平均分 AS AVG(cj) FROM xscj; WHERE kch="410001" ORDER BY班级
在SQL的查询语句中，实现关系的投影操作的短语为()。
A. FROM
B. SELECT
C. JOIN…ON
D. WHERE
设有关系SC(SNO,CNO,GRADE),其中SNO、CNO分别表示学号、课程号(两者均为字符型)，GRADE表示成绩(数值型)，若要把学号为“S101”的同学，选修课程号为“C11”,成绩为98分的记录插到表SC中，正确的语句是()。
A. INSERT INTO SC(SNO,CNO,GRADE) valueS ('S101','C11','98')
B. INSERT INTO SC(SNO,CNO,GRADE) values (S101, C11, 98)
C. INSERT ('S101','C11','98') INTO SC
D. INSERT INTO SC valueS ('S101','C11',98)
微信支付 
支付宝支付