parameters using 

SQLBindParameter(),

 and finally execution of the 

query using 

SQLExecute()

. Example 7 48 shows an example for 

prepared statements.

  Prepare and execute in a single step

If your query is executed only once, then you can use 

SQLExecDirect() 

to directly call, prepare, and execute in a single step. Example 7 49 

shows the usage of this method.

c. Processing results

Processing query results involves binding application variables to columns 

of a result set, and then fetching the rows of data into the application 

variables. This is done by calling 

SQLBindCol()

 followed by 

SQLFetch() 

as 

shown in Example 7 48. 

Another way to get data without binding the column is by calling 

SQLFetch()

 and 

SQLGetData()

, this technique is used in Example 7 49.

d. Committing or rolling back 

DB2 UDB supports two commit modes: auto commit and manual commit. 

This can be set using 

SQLSetConnectAttr()

 with the parameter 

SQL_AUTOCOMMIT_ON

 or

SQL_AUTOCOMMIT_OFF

. If a transaction is set to 

SQL_AUTOCOMMIT_OFF

 it is the programmer's responsibility to end the 

transaction. This can be done using 

SQLEndTran()

 to either rollback or 

commit the transaction using parameter 

SQL_COMMIT

 or 

SQL_ROLLBACK

. 

e. Deallocating statement handle

This requires unbinding of the variables, columns, or cursors (if allocated) 

using 

SQLFreeStmt()

 with the option of 

SQL_CLOSE

, SQL_UNBIND 

or 

SQL_RESET_PARAMS,

 and then finally calling

 SQLFreeHandle()

 to 

deallocate the statement handle.

Example 7 48   DB2 CLI prepared statement with column binding, auto commit on

SQLHANDLE hstmt; /* statement handle */

SQLINTEGER wk_id=10;

SQLINTEGER user_id;

SQLCHAR val[15];

/* SQL statements to execute */

SQLCHAR *stmt1 = (SQLCHAR *)"SELECT user_id,status FROM warenkorb where 

wk_id=?";

/* set AUTOCOMMIT on */

ret = SQLSetConnectAttr(hdbc,

SQL_ATTR_AUTOCOMMIT,

 Chapter 7. Application porting 

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