[C++] sqlite3_get_table 的使用

不知道为啥 sqlite3 里面使用 “UPDATE” 更新数据，更新失败也不报错，所以就想绕过去。先查一下字段存在不存在，然后再update

std::string selectsql =  "SELECT COUNT(*) FROM table_name WHERE some_condition";
char** dbResult;
char* errmsg = NULL;        //用来存储错误信息字符串
int nRow = 0, nColumn = 0;  // nRow  查找出的总行数,nColumn 存储列
int ret = sqlite3_get_table(db, selectsql.c_str(), &dbResult, &nRow, &nColumn, &errmsg);
if (SQLITE_OK != ret || nRow == 0)
{

    sqlite3_free_table(dbResult);
   // do_something
}
 sqlite3_free_table(dbResult);
// do_something


std::string sql = "UPDATE table_name SET item1=? \
    WHERE item2=? and item3=? and item4=?;  ";

sqlite3_prepare_v2(db, sql.c_str(), -1, &statement, nullptr);
int index = 0;
QByteArray inByteArray
sqliteBind(statement, index, inByteArray.data(), inByteArray.length());  
sqliteBind(statement, index, "...");         
sqliteBind(statement, index, "...");  
sqliteBind(statement, index, "...");