我有一个结构
的表TBL_CLASSCLASS_NAME | CLASS_TYPE
Maths PRI
Math SEC
English PRI
English PAR
Physics PAR
Biology BIO
我想要做的是使用值Maths和从0001开始而不是1的序列更新ClassCode列，以便上面的表格成为
CLASS_NAME | CLASS_TYPE | CLASS_CODE
Maths MATH MATH0001
Math MATH MATH0002
English ENG ENG0001
English ENG ENG0002
Physics PHY PHY0001
Biology BIO BIO0001
是否可以在数据库中执行此操作而不用每列填充MATH0001或ENG0001的第一列或创建临时列？
我可以用序列创建一个临时列，但是我仍然需要在列中填入第一个数字，然后选择MAX
SELECT MAX(substr(TEMP_CODE, -4)) AS LAST4DIGIT FROM TBL_CLASS WHERE CLASS_TYPE= 'MATHS'
然后使用更新语句
更新列UPDATE TBL_CLASS SET CLASS_CODE = CLASS_TYPE||TEMP_COL
我想要实现的是使用类似
的语句更新ClassCode UPDATE TBL_CLASS SET CLASS_CODE = CLASS_NAME|| <sequence>没有填写每个类的第一个值（0001）并将序列添加到临时列中。
感谢关于我如何处理这个问题的任何指示。
答案 0 :(得分：0)
此SQL显示了如何使用列输出进行操作。如果这是您想要的，您可以使用它来更新您的表。如果你需要添加一个新的（例如数学）行，需要找到你可以使用的索引号，例如。 /*
The Great Quiz Show Game
by
Seth A----
*/
#include <iostream>
#include <string>
using namespace std;
int Guess;
int Winnings;
//Define question class
class Question
{
private:
string Question_Text;
string Answer_1;
string Answer_2;
string Answer_3;
string Answer_4;
int Correct_Answer;
int Prize_Ammount;
public
:void setValues(string, string, string, string, string, int, int);
void askQuestion();
};
int main()
{
//declare local variables
int High_Score[5];
string High_Score_Name[5];
//initialize local variable
High_Score[0] = 25000;
High_Score[1] = 12000;
High_Score[2] = 7500;
High_Score[3] = 4000;
High_Score[4] = 2000;
High_Score_Name[0] = "Gweneth";
High_Score_Name[1] = "Adam";
High_Score_Name[2] = "Nastasia";
High_Score_Name[3] = "Nicolas";
High_Score_Name[4] = "Dani";
cout << "***********************" << endl;
cout << "* *" << endl;
cout << "* The Great Quiz Show *" << endl;
cout << "* *" << endl;
cout << "* by *" << endl;
cout << "* *" << endl;
cout << "* Seth Alpha *" << endl;
cout << "* *" << endl;
cout << "***********************" << endl;
cout << endl;
//instances of questions
Question q1;
Question q2;
q1.setValues("What does cout do?",
"Eject a CD",
"Send text to the printer",
"Print text on the screen",
"Play a sound",
3,
2500);
q2.setValues("What are the two sections in a class?",
"Public and local",
"Global and local",
"Global and private",
"Public and private",
4,
5000);
//ask questions
q1.askQuestion();
q2.askQuestion();
//print HS list
cout << "High Score List" << endl;
cout << endl;
for (int i = 0; i < 5; i++)
{
cout << High_Score[i] << "" << High_Score_Name[i] << endl;
}
}
void Question::setValues(string q, string a1, string a2, string a3, string a4, int ca, int pa)
{
Question_Text = q;
Answer_1 = a1;
Answer_2 = a2;
Answer_3 = a3;
Answer_4 = a4;
Correct_Answer = ca;
Prize_Ammount = pa;
}
void Question::askQuestion()
{
cout << endl;
cout << "What does cout do?" << endl;
cout << "1." << Answer_1 << endl;
cout << "2." << Answer_2 << endl;
cout << "3." << Answer_3 << endl;
cout << "4." << Answer_4 << endl;
cout << endl;
//ask for guess
cout << "What is your answer?" << endl;
cin >> Guess;
//if correct add Prize_Ammount to Winnings
if (Guess == Correct_Answer)
{
cout << endl;
cout << "You are correct!" << endl;
Winnings = Winnings + Prize_Ammount
; cout << "You just won $" << Prize_Ammount << "!" << endl;
cout << "Total winnings: $" << Winnings << endl;
cout << endl;
}
else
{
cout << endl;
cout << "You are not correct" << endl;
cout << "Total winnings: $" << Winnings << endl;
cout << endl;
}
}
仅提取数字，然后删除前零（并添加1）。
REGEXP_SUBST 编辑：我没有意识到SELECT class_name,
SUBSTR (UPPER (class_name),
1,
CASE WHEN UPPER (class_name) LIKE 'MATH%' THEN 4 ELSE 3 END)
class_type,
SUBSTR (
UPPER (class_name),
1,
CASE WHEN UPPER (class_name) LIKE 'MATH%' THEN 4 ELSE 3 END)
|| LPAD (
ROW_NUMBER () OVER (PARTITION BY class_type ORDER BY class_type),
4,
'0')
class_code
FROM tbl_class
条款可能会引起误解，所以我删除了它。