Reading to a Buffer

Introduction

This query allows you to retrieve the data in a field. You can retrieve one entry or multiple entries in the same column by executing the query in a loop.

Basic procedure

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

1. Configure the SQL statement.

2. Allocate memory and copy data.

3. Deallocate memory.

Detailed steps

The steps to read data to a buffer are as follows:

Configure the SQL statement

Instantiate an RSqlStatement object and declare the variables as required.

       
        
       
       RSqlStatement myStatement;
TInt err;
      

Allocate memory and copy data

To retrieve all the entries, use a loop. The steps to be performed within the loop are as described below:

1. Instantiate an object of the RBuf class.

            
             
            
            while((err = myStatement.Next()) == KSqlAtRow)
       {
       RBuf myBuffer;
           

2. Allocate enough memory to hold the column data using the CreateL() function as shown below.

            
             
            
            err = myBuffer.CreateL(myStatement.ColumnSize(columnIndex));
           

3. Copy the data from the table into the buffer using RSqlStatement::ColumnBinary(TInt,TDes8 &)const function.

            
             
            
            err = myStatement.ColumnBinary(myColumnIndex,myBuffer);
       ...
       // process data
           

Deallocate memory

Deallocate the memory assigned to the RBuf object.

       
        
       
       myBuffer.Close();
    }
      

See also

Querying a Database

Deleting Rows from a Table

Reading to a buffer - This document

Reading to Memory

Reading to a Data Stream

Writing to a Data Stream

Performing Scalar Queries