If a NULL value is single-row inserted into a column declared as NOT NULL, an error will be ...
if the SQL mode is not strict (default until MariaDB 10.2.3), if a NULL value is multi-r...
intrc = sqlite3_prepare_v2(db, sql.GetString(), -1, &stmt,NULL); if(rc != SQLITE_OK) { MessageBox("sqlite3_prepare_v2 Failed!"); return; } count= 0; p_wnd = PrevWnd; CString DbStr[ID_TOTALCOUNT + 1]; while(count++ < ID_TOTALCOUNT) { DbStr[count].Empty(); p_wnd = ...
tvins.hParent=hPrevRootItem;elsetvins.hParent=hPrevLev2Item;//Add the item to the tree-view control.hPrev =(HTREEITEM)SendMessage(hwndTV, TVM_INSERTITEM,0, (LPARAM)(LPTVINSERTSTRUCT)&tvins);if(hPrev ==NULL)returnNULL;//Save the handle to the item.if(nLevel ==1) hPrevRootItem=h...
isEmpty()) { std::cout << "db filename is empty" << std::endl; return; } (void)open_db(dbFileName); } bool SqliteUtil::fun_insert_file(QByteArray buffer, QString sqlstr) { sqlite3_stmt *stmt = NULL; //插入的sql语句,这里用?占位,代表BLOB数据 auto rc = sqlite3_prepare_v2(...
所以,当SQLite对一个字段进行排序时,首先按存储类排序,然后再进行类内的排序 (NULL类内部各值不必排序) 。 回到顶部 性能优化 1、优化策略一: 插入语句的书写方式 逐行插入的效率远远低于多行插入 开发中,我们尽量多些多行插入,避免出现逐行插入的操作。
if(p!=null) { foreach(objectparminp) cmd.Parameters.AddWithValue(string.Empty, parm); } } publicstaticDataSet ExecuteQuery(stringcmdText,paramsobject[] p) { using(SQLiteConnection conn=newSQLiteConnection(ConnectionString)) { using(SQLiteCommand command=newSQLiteCommand()) ...
Currently the only way to determine if a field contains a null value is with theFieldIsNullmethod. The other methods return zero, false or empty strings for null values. I will be publising a basic tutorial on using the wrapper in the UK magazinePC Plus. I will also keep this page up...
(const char* szField, double fNullValue/*=0.0*/) { int nField = fieldIndex(szField); return getFloatField(nField, fNullValue); } const char* CppSQLite3Query::getStringField(int nField, const char* szNullValue/*=""*/) { if (fieldDataType(nField) == SQLITE_NULL) { return szNull...
int CbSqlite3::queryData(std::string sql, CbSqlite3Results &results) { int ret = 0; // 数据库操作指针为空,返回sqlite错误码 if (_pDB == NULL) { return SQLITE_ERROR; } // 保存sql语句 results._sql = sql; // 清空数组 results.empty(); ...