Navigating the rows of a table

The UltraLite C++ API provides you with several methods to navigate a table to perform a wide range of navigation tasks. For more information about the ULTable class, see ULTable class.

The ULTable object provides you with the following methods to navigate a table:

AfterLast Position immediately after the last row.
BeforeFirst Position immediately before the first row.
First Move to the first row.
Last Move to the last row.
Next Move to the next row.
Previous Move to the previous row.
Relative(offset) Move a specified number of rows relative to the current row, as specified by the signed offset value. Positive offset values move forward in the result set, relative to the current pointer position in the result set. Negative offset values move backward in the result set. An offset value of zero does not move the current location, but allows you to repopulate the row buffer.

Example

The following example opens the table named MyTable and displays the value of the column named MyColumn for each row:

char buffer[ 100 ];
ul_column_num column_id;
ULTable * tbl = conn->OpenTable( "MyTable" );
if( tbl == NULL ) {
    const ULError * ulerr;
    ulerr = conn->GetLastError();
    // write code to handle the error
    return;
}
column_id = tbl->GetTableSchema().GetColumnID( "MyColumn" );
if( column_id == 0 ) {
    // the column "MyColumn" likely does not exist.  Handle the error.
    tbl->Close();
    return;
}
while( tbl->Next() ) {
    tbl->GetString( column_id, buffer, 100 );
    printf( "%s\n", buffer );
}
tbl->Close();

You expose the rows of the table to the application when you open the ULTable object. By default, the rows are ordered by primary key value but you can specify an index when opening a table to access the rows in a particular order.