7.10 疑难解析

public boolean InsertOrUpdate_Obj_gradeinfo_sub(Obj_gradeinfo_sub[] object){
try{
stmt = con.createStatement();
for (int i = 0; i < object.length; i++) {
String sqlStr = null;
//此处省略了部分代码
stmt.addBatch(sqlStr);
}
// 执行批处理命令进行数据存盘操作
stmt.executeBatch();
JOptionPane.showMessageDialog(null, "学生成绩数据存盘成功!!!", "系统提示",
JOptionPane.INFORMATION_MESSAGE);
}catch(java.sql.SQLException sqlerror) {
new appstu.view.JF_view_error("错误信息为：" +sqlerror.getMessage());
return false;
}
return true;
}

for (int i = 0 ; i < object.length ; i++){
String code = null,subject = null;
java.util.Vector vdata = null;
vdata = (java.util.Vector)object[i];
code = String.valueOf(vdata.get(0));
subject = String.valueOf(vdata.get(1));
tbname[i+2] = subject;
if ( (i + 1) == object.length){
sqlStr = sqlStr + " SUM(CASE code WHEN '" + 

code + "' THEN grade ELSE 0 END) AS '" + subject + "'";
}else{
sqlStr = sqlStr + " SUM(CASE code WHEN '" + 
code + "' THEN grade ELSE 0 END) AS '" + subject + "',";
}
}

SELECT stuid, stuname,  SUM(CASE code WHEN 
'01' THEN grade ELSE 0 END) AS '数学', 
SUM(CASE code WHEN '02' THEN grade ELSE 0 
END) AS '外语', SUM(CASE code WHEN '04' 
THEN grade ELSE 0 END) AS '化学', SUM(CASE
code WHEN '05' THEN grade ELSE 0 END) AS '
政治' FROM tb_gradeinfo_sub  where kindID = '
01' and subString(stuid,1,4) = '0102'  GROUP 
BY stuid,stuname