2.5 KiB
DatabaseOpen
Opens or creates a database in a specified file.
int DatabaseOpen(
string filename, // file name
uint flags // combination of flags
);
Parameters
filename
[in] File name relative to the "MQL5\Files" folder.
flags
[in] Combination of flags from the ENUM_DATABASE_OPEN_FLAGS enumeration.
Return Value
If executed successfully, the function returns the database handle, which is then used to access the database. Otherwise, it returns INVALID_HANDLE. To get the error code, use GetLastError(), the possible responses are:
-
ERR_INTERNAL_ERROR (4001) – critical runtime error;
-
ERR_WRONG_INTERNAL_PARAMETER (4002) - internal error, while accessing the "MQL5\Files" folder;
-
ERR_INVALID_PARAMETER (4003) – path to the database file contains an empty string, or an incompatible combination of flags is set;
-
ERR_NOT_ENOUGH_MEMORY (4004) - insufficient memory;
-
ERR_WRONG_FILENAME (5002) - wrong database file name;
-
ERR_TOO_LONG_FILENAME (5003) - absolute path to the database file exceeds the maximum length;
-
ERR_DATABASE_TOO_MANY_OBJECTS (5122) - exceeded the maximum acceptable number of Database objects;
-
ERR_DATABASE_CONNECT (5123) - database connection error;
-
ERR_DATABASE_MISUSE (5621) - incorrect use of the SQLite library.
Note
If the filename parameter features NULL or the empty string "", a temporary file is created on the disk. It is automatically deleted after closing the database connection.
If the filename parameter features ":memory:", the database is created in the memory and is automatically deleted after the connection to it is closed.
If the flags parameter features none of the DATABASE_OPEN_READONLY or DATABASE_OPEN_READWRITE flags, the DATABASE_OPEN_READWRITE flag is used.
If the file extension is not specified, ".sqlite" is used.
ENUM_DATABASE_OPEN_FLAGS
| ID | Description |
|---|---|
| DATABASE_OPEN_READONLY | Read only |
| DATABASE_OPEN_READWRITE | Open for reading and writing |
| DATABASE_OPEN_CREATE | Create the file on a disk if necessary |
| DATABASE_OPEN_MEMORY | Create a database in RAM |
| DATABASE_OPEN_COMMON | The file is in the common folder of all terminals |
See also