9.4 KiB
9.4 KiB
DatabaseBindArray
Sets an array as a parameter value.
bool DatabaseBind(
int request, // the handle of a request created in DatabasePrepare
int index, // the parameter index in the request
T& array[] // parameter value as an array
);
Parameters
request
[in] The handle of a request created in DatabasePrepare().
index
[in] The parameter index in the request a value should be set for. The numbering starts with zero.
array[]
[in] The array to be set as a request parameter value.
Return Value
Returns true if successful, otherwise - false. To get the error code, use GetLastError(), the possible responses are:
- ERR_INVALID_PARAMETER (4003) – unsupported type;
- ERR_ARRAY_BAD_SIZE (4011) - array size in bytes exceeds INT_MAX;
- ERR_DATABASE_INVALID_HANDLE (5121) - invalid database handle;
- ERR_DATABASE_NOT_READY (5128) - cannot use the function to make a request at the moment (the request is being executed or already complete, DatabaseReset should be called).
Note
The function is used in case an SQL request contains "?" or "?N" parameterizable values where N means the parameter index (starting from one). At the same time, parameters indexing in DatabaseBindArray() starts from zero.
For example:
INSERT INTO table VALUES (?,?,?)
The function may be called immediately after a parametrized request is created in DatabasePrepare() or after the request is reset using DatabaseReset().
Use this function together with DatabaseReset() to execute the request as many times as needed with different parameter values.
Example:
//+------------------------------------------------------------------+
//| Script program start function |
//+------------------------------------------------------------------+
void OnStart()
{
//--- open the dialog for selecting files with the DAT extension
string selected_files[];
if(!FileSelectDialog("Select files to download", NULL,
"Data files (*.dat)|*.dat|All files (*.*)|*.*",
FSD_ALLOW_MULTISELECT, selected_files, "tester.dat")>0)
{
Print("Files not selected. Exit");
return;
}
//--- get the size of files
ulong filesize[];
int filehandle[];
int files=ArraySize(selected_files);
ArrayResize(filesize, files);
ZeroMemory(filesize);
ArrayResize(filehandle, files);
double total_size=0;
for(int i=0; i<files; i++)
{
filehandle[i]=FileOpen(selected_files[i], FILE_READ|FILE_BIN);
if(filehandle[i]!=INVALID_HANDLE)
{
filesize[i]=FileSize(filehandle[i]);
//PrintFormat("%d, %s handle=%d %d bytes", i, selected_files[i], filehandle[i], filesize[i]);
total_size+=(double)filesize[i];
}
}
//--- check the common size of files
if(total_size==0)
{
PrintFormat("Total files size is 0. Exit");
return;
}
//--- create or open the database in the common terminal folder
string filename="dat_files.sqlite";
int db=DatabaseOpen(filename, DATABASE_OPEN_READWRITE | DATABASE_OPEN_CREATE);
if(db==INVALID_HANDLE)
{
Print("DB: ", filename, " open failed with code ", GetLastError());
return;
}
else
Print("Database: ", filename, " opened successfully");
//--- if the FILES table exists, delete it
if(DatabaseTableExists(db, "FILES"))
{
//--- delete the table
if(!DatabaseExecute(db, "DROP TABLE FILES"))
{
Print("Failed to drop table FILES with code ", GetLastError());
DatabaseClose(db);
return;
}
}
//--- create the FILES table
if(!DatabaseExecute(db, "CREATE TABLE FILES("
"NAME TEXT NOT NULL,"
"SIZE INT NOT NULL,"
"PERCENT_SIZE REAL NOT NULL,"
"DATA BLOB NOT NULL);"))
{
Print("DB: failed to create table FILES with code ", GetLastError());
DatabaseClose(db);
return;
}
//--- display the list of all fields in the FILES table
if(DatabasePrint(db, "PRAGMA TABLE_INFO(FILES)", 0)<0)
{
PrintFormat("DatabasePrint(\"PRAGMA TABLE_INFO(FILES)\") failed, error code=%d at line %d", GetLastError(), __LINE__);
DatabaseClose(db);
return;
}
//--- create a parametrized request to add files to the FILES table
string sql="INSERT INTO FILES (NAME,SIZE,PERCENT_SIZE,DATA)"
" VALUES (?1,?2,?3,?4);"; // request parameters
int request=DatabasePrepare(db, sql);
if(request==INVALID_HANDLE)
{
PrintFormat("DatabasePrepare() failed with code=%d", GetLastError());
Print("SQL request: ", sql);
DatabaseClose(db);
return;
}
//--- go through all the files and add them to the FILES table
bool request_error=false;
DatabaseTransactionBegin(db);
int count=0;
uint size;
for(int i=0; i<files; i++)
{
if(filehandle[i]!=INVALID_HANDLE)
{
char data[];
size=FileReadArray(filehandle[i], data);
if(size==0)
{
PrintFormat("FileReadArray(%s) failed with code %d", selected_files[i], GetLastError());
continue;
}
count++;
//--- set the values of the parameters before adding the file to the table
if(!DatabaseBind(request, 0, selected_files[i]))
{
PrintFormat("DatabaseBind() failed at line %d with code=%d", __LINE__, GetLastError());
request_error=true;
break;
}
if(!DatabaseBind(request, 1, size))
{
PrintFormat("DatabaseBind() failed at line %d with code=%d", __LINE__, GetLastError());
request_error=true;
break;
}
if(!DatabaseBind(request, 2, double(size)*100./total_size))
{
PrintFormat("DatabaseBind() failed at line %d with code=%d", __LINE__, GetLastError());
request_error=true;
break;
}
if(!DatabaseBindArray(request, 3, data))
{
PrintFormat("DatabaseBind() failed at line %d with code=%d", __LINE__, GetLastError());
request_error=true;
break;
}
//--- execute a request for inserting the entry and check for an error
if(!DatabaseRead(request)&&(GetLastError()!=ERR_DATABASE_NO_MORE_DATA))
{
PrintFormat("DatabaseRead() failed with code=%d", GetLastError());
DatabaseFinalize(request);
request_error=true;
break;
}
else
PrintFormat("%d. %s: %d bytes", count, selected_files[i],size);
//--- reset the request before the next parameter update
if(!DatabaseReset(request))
{
PrintFormat("DatabaseReset() failed with code=%d", GetLastError());
DatabaseFinalize(request);
request_error=true;
break;
}
}
}
//--- transactions status
if(request_error)
{
PrintFormat("Table FILES: failed to add %d files", count);
DatabaseTransactionRollback(db);
DatabaseClose(db);
return;
}
else
{
DatabaseTransactionCommit(db);
PrintFormat("Table FILES: added %d files", count);
}
//--- close the database file and inform of that
DatabaseClose(db);
PrintFormat("Database: %s created and closed", filename);
}
See also