使用嵌入式SQL对学生-课程数据库中的表完成下述功能

Posted 2021-07-23 weixin_43739821

使用嵌入式SQL对学生-课程数据库中的表完成下述功能
(1）查询某一门课程的信息。要查询的课程由用户在程序运行过程中指定，放在主变量中。
(2）查询选修某一门课程的选课信息，要查询的课程号由用户在程序运行过程中指定，放在主变量中,然后根据用户的要求修改其中某些记录的成绩字段。

（1）

EXEC SQL SELECT Cno,Cname,Cpno,Credit
	INTO :Hcno,:Hcname,:Hcpno,:Hcredit
	FORM Course
	WHERE Cname=:givencname;

(2)

	//Wirten By Tanxin-ouc
	EXEC SQL BEGIN DECLARE SECTION;//主变量说明开始
	char Hsno[64];
	char Hcno[64];
	int Hgrade;
	int NEWGRADE;
	EXEC SQL END DECLARE SECTION;//主变量说明结束
	long SQLCODE;
	EXEC SQL INCLUDE sqlca;//定义SQL通信区
	int main(void)
	{
		int count = 0;
		char yn; //变量yn代表yes或no
		printf("Please input the calss number:");
		scanf("%s", &classno);
		EXEC SQL CONNECT TO TEST@ localhost:54321 USER "SYSTEM" / "MANAGER";//链接数据库TEST
		EXEC SQL DECLARE SX CURSOR FOR//定义游标SX
			SELECT Sno, Cno, Grade
			FROM SC
			WHERE Cno = :classno;
		EXEC SQL OPEN SX;
		for (;;)
		{
			EXEC SQL FETCH SX INTO : HSno, : Hcno, : Hgrade;
			if (sqlca.sqlcode != 0)
				break;
			if (count++ == 0)
				printf("\\n%-10s%-20s%-10s\\n", "Sno", "Cno", "Grade");

			printf("%-10s%-20s%-10d\\n", HSno, Hcno, Hgrade);

			printf("UPDATE GRADE(y/n)?");
			do {
				scanf("%c", &yn);
			} while (yn != 'N' && yn != 'n' && yn != 'Y' && yn != 'y');
			if (yn == 'y' || yn == 'Y')
			{
				printf("INPUT NEW GRADE:");
				scanf("%d", &NEWGRADE);
				EXEC SQL UPDATE SC//嵌入式SQL更新语句
					SET Grade = :NEWGRADE
					WHERE CURRENT OF SX;
			}
		}
		EXEC SQL CLOSE SX;//关闭游标SX
		EXEC SQL COMMIT WORK;//提交更新
		EXEC SQL DISCONNECT TEST;//断开数据库连接
	}