Preparing the Output XSQLDA to Read Data from an Array

Go Up to Reading Data from an Array

Most queries return one or more rows of data, referred to as a select-list. An output XSQLDA must be created to store the column data for each row that is fetched. For an array column, the column data is an internal array identifier (array ID) that is needed to access the actual data. To prepare the XSQLDA, follow these steps:

1. Declare a variable to hold the XSQLDA. For example, the following declaration creates an XSQLDA called ­out_sqlda:

   XSQLDA *out_sqlda;
   

2. Allocate memory for the XSQLDA using the XSQLDA_LENGTH macro. The XSQLDA must contain one XSQLVAR substructure for each column to be fetched. The following statement allocates storage for an output XSQLDA (out_sqlda) with two XSQLVAR substructures:

   out_sqlda = (XSQLDA *)malloc(XSQLDA_LENGTH(2));
   

3. Set the version field of the XSQLDA to SQLDA_CURRENT_VERSION, and set the sqln field of the XSQLDA to indicate the number of XSQLVAR substructures allocated:

   out_sqlda->version = SQLDA_CURRENT_VERSION;
   out_sqlda->sqln = 2;
   

Advance To:

• Preparing the SELECT Statement to Read Data from an Array for Execution