#include <iostream>
using namespace std;class A
{
public:int a;A(int a):a(a){cout<<"A的有参构造"<<endl;}
};
class B:virtual public A
{
public:int b;B(int a,int b):A(a),b(b){cout<<"B的有参构造"<<endl;}
};
cl…
查询表是否存在
使用 SHOW TABLES
SHOW TABLES LIKE %tbl_tabl%;结果: 查询 INFORMATION_SCHEMA
// like 匹配
SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES where TABLE_SCHEMA test AND TABLE_NAME like %tbl%;
// 完全匹配
SELECT TABLE_NAME FROM INFORMATION_SC…