Reading to a Data Stream

Introduction

You can read data from the table into a data stream in one chunk or in bits as desired.

Basic procedure

The high level steps to read the data into a data stream are shown here:

1. Configure your SQL statement and data stream.

2. Read data to a stream.

3. Clean up.

Detailed steps

To read the data into a data stream, do the following:

Configure your SQL statement and data stream

1. As a first step instantiate an object of the RSqlStatement and RSqlColumnReadStream class. Also declare the variables as required.

            
             
            
            RSqlStatement myStatement;
   TInt err;
   TInt myColumnIndex;
   RSqlColumnReadStream myStream;
           

2. Clean up the stack.

            
             
            
            CleanupClosePushL(myStream);
           

Read data to a stream

1. Open the stream for read and associate the data with it.

            
             
            
            User::LeaveIfError(myStream.ColumnBinary(myStatement,myColumnIndex));
           

2. Determine the column size.

            
             
            
            TInt size = myStatement.ColumnSize(myColumnIndex);
           

3. Instantiate an object of the RBuf class. Create a buffer of the size of the column. Then read the data into the buffer.

            
             
            
            RBuf buf;
           buf.CreateL(size);
           CleanupClosePushL(buf);
           myStream.ReadL(buf,size);
           

4. Close the buffer.

            
             
            
            CleanupStack::PopAndDestroy();
           

Clean up

Close the stream.

       
        
       
       CleanupStack::PopAndDestroy();
      

See also

Querying a Database

Inserting a Row into a Table

Deleting Rows from a Table

Reading to a Buffer

Reading to Memory

Reading to a Data Stream - This document

Writing to a Data Stream

Performing Scalar Queries