PhpAdmin作为MySQL的一种图形化管理工具,其工作模式为()。
A. C/S模式
B/S模式
C. 命令行方式
D. 脚本方式
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调用存储函数的命令为()。
A. DECLARE
B. EXE
C. SELECT
D. CALL
下列关于触发器的定义中,正确的是()。
A. DELIMITER $$ CREATE TRIGGER tr_stu AFTER INSERT ON tb_student FOR EACH ROW BEGIN DELETE FROM tb_sc WHERE sno=OLD.sno; END$$
B. DELIMITER $$ CREATE TRIGGER tr_stu AFTER DELETE ON tb_student FOR EACH ROW BEGIN DELETE FROM tb_sc WHERE sno=OLD.sno; END$$
C. DELIMITER $$ CREATE TRIGGER tr_stu BEFORE INSERT(sno) ON tb_student FOR EACH ROW BEGIN DELETE FROM tb_sc WHERE sno=NEW.sno; END$$
DELIMITER $$ CREATE TRIGGER tr_stu AFTER DELETE ON tb_student FOR EACH ROW BEGIN DELETE FROM tb_sc WHERE sno=NEW.sno; END$$
设smajor是student表中的一个字段,以下能够正确判断smajor字段是否为空值的表达式是()。
A. smajor = NULL
B. smajor IS NULL
C. smajor=0
D. smajor=’’
设有一个成绩表Student_JAVA(id,name,grade),现需要查询成绩grade第二名的同学信息(假设所有同学的成绩各不相同),正确的SQL语句应该是()。
A. SELECT * FROM Student_JAVA ORDER BY grade limit 1,1;
B. SELECT * FROM Student_JAVA ORDER BY grade DESC limit 1,1;
C. SELECT * FROM Student_JAVA ORDER limit 1,1;
D. SELECT * FROM Student_JAVA ORDER BY grade DESC limit 0,1;