创建一张用户表,表名及表结构如下:Member(m_id,m_birth,m_sex)
时间: 2024-02-17 10:01:58 浏览: 26
下面是创建一个名为Member的用户表,包含三个字段m_id、m_birth、m_sex的SQL语句:
```
CREATE TABLE Member (
m_id INT PRIMARY KEY,
m_birth DATE,
m_sex VARCHAR(10)
);
```
解释一下:
- CREATE TABLE:创建一张表
- Member:表名
- m_id、m_birth、m_sex:表中的三个字段
- INT:整数类型
- DATE:日期类型
- VARCHAR(10):可变长度字符串类型,最大长度为10
- PRIMARY KEY:主键声明,用于唯一标识每一行数据。在 Member 表中,m_id 字段是主键。
相关问题
std::string::max_size() cannot call member function
I apologize for the confusion. You are correct that `std::string::max_size()` is a static member function and should be called on the string class itself, not on an instance of `std::string`.
Here's the correct usage:
```cpp
#include <iostream>
#include <string>
int main() {
std::cout << "Max size of std::string: " << std::string::max_size() << std::endl;
return 0;
}
```
In this example, `std::string::max_size()` is called without an instance of `std::string`. It returns the maximum number of elements (characters) that a `std::string` can hold.
Again, I apologize for the confusion caused by the incorrect information in my previous response. Thank you for pointing it out.
Q_PROPERTY(QString content MEMBER m_content)
This is a Qt macro used to declare a property named "content" of type QString with a member variable named "m_content". This macro can be used in a QObject-derived class to expose the member variable as a property that can be accessed and modified by other objects using Qt's meta-object system. For example, if you have a class named "MyClass" that inherits from QObject and has a member variable named "m_content" of type QString, you can declare a property for it using the following code:
```
class MyClass : public QObject
{
Q_OBJECT
Q_PROPERTY(QString content MEMBER m_content)
public:
QString m_content;
};
```
This will allow other objects to access and modify the "content" property of MyClass using the Qt meta-object system. For example, if you have an instance of MyClass named "myObject", you can access its "content" property like this:
```
QString content = myObject.property("content").toString();
myObject.setProperty("content", "new content");
```
Note that in order to use the Q_PROPERTY macro, your class must also inherit from QObject and include the Q_OBJECT macro.
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