<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html lang="en-us" xml:lang="en-us">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="security" content="public" />
<meta name="Robots" content="index,follow" />
<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
<meta name="DC.Type" content="reference" />
<meta name="DC.Title" content="Retrieve results" />
<meta name="abstract" content="In order to work with all of the rows in a result set, call the SQLFetch API until no more rows are returned." />
<meta name="description" content="In order to work with all of the rows in a result set, call the SQLFetch API until no more rows are returned." />
<meta name="DC.Relation" scheme="URI" content="rzaikodbcapiinfo.htm" />
<meta name="copyright" content="(C) Copyright IBM Corporation 1999, 2006" />
<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1999, 2006" />
<meta name="DC.Format" content="XHTML" />
<meta name="DC.Identifier" content="retrieveresults" />
<meta name="DC.Language" content="en-us" />
<!-- All rights reserved. Licensed Materials Property of IBM -->
<!-- US Government Users Restricted Rights -->
<!-- Use, duplication or disclosure restricted by -->
<!-- GSA ADP Schedule Contract with IBM Corp. -->
<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
<link rel="stylesheet" type="text/css" href="./ic.css" />
<title>Retrieve results</title>
</head>
<body id="retrieveresults"><a name="retrieveresults"><!-- --></a>
<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
<h1 class="topictitle1">Retrieve results</h1>
<div><p>In order to work with all of the rows in a result set, call the <strong>SQLFetch</strong> API
until no more rows are returned.</p>
<div class="section"><p>Running some <span class="keyword">SQL</span> statements
returns results to the application program. Running an <span class="keyword">SQL</span> SELECT
statement returns the selected rows in a result set. The <strong><span class="keyword">SQL</span>Fetch</strong> API
then sequentially retrieves the selected rows from the result set into the
application program's internal storage. </p>
</div>
<div class="section"><p>You also may issue a Select statement where you do not specify
what columns you want returned. For example, <samp class="codeph">SELECT * FROM RWM.DBFIL</samp> selects
all columns. You may not know what columns or how many columns will be returned. </p>
<dl><dt class="dlterm">SQLNumResultCols</dt>
<dd>Returns the number of columns in a result set. <ul><li>A storage buffer that receives the information is passed as a parameter.</li>
</ul>
<pre> SQLSMALLINT nResultCols;
rc = SQLNumResultCols(hstmt, &nResultCols);</pre>
</dd>
<dt class="dlterm">SQLDescribeCol</dt>
<dd>Returns the result descriptor for one column in a result set. <ul><li><strong>Column name</strong></li>
<li><strong>Column type</strong></li>
<li><strong>Column size</strong> <p>This is used with <strong>SQLNumResultCols</strong> to retrieve
information about the columns returned. Using this approach, as opposed to
hard coding the information in the program, makes for more flexible programs.</p>
<p>The
programmer first uses <strong>SQLNumResultCols</strong> to find out how many columns
were returned in the result set by a select statement. Then a loop is set
up to use <strong>SQLDescribeCol</strong> to retrieve information about each column.</p>
</li>
</ul>
<p>In C, this statement is coded: </p>
<pre>
SQLCHAR szColName[51];
SQLSMALLINT lenColName, colSQLtype, scale, nullable;
SQLUSMALLINT colNum = 1;
SQLUINTEGER cbColDef;
rc = SQLDescribeCol(hstmt, colNum, szColName, sizeof(szColName),
&lenColName, &colSQLtype, &cbColDef, &scale, &nullable);</pre>
</dd>
<dt class="dlterm">SQLBindCol</dt>
<dd>Assigns the storage and data type for a column in a result set: <ul><li>Storage buffer that receives the information.</li>
<li>Length of storage buffer.</li>
<li>Data type conversion.</li>
</ul>
<p>In C, this statement is coded: </p>
<pre>SQLUSMALLINT colNum = 1;
SQLUINTEGER cbColDef;
SQLINTEGER idNum, indPtr, strlen_or_indPtr;
SQLCHAR szIDName[51];
colNum = 1;
rc = SQLBindCol(hstmt, colNum, SQL_C_LONG, &idNum, sizeof(SQLINTEGER), &indPtr);
colNum = 2;
rc = SQLBindCol(hstmt, colNum, SQL_C_CHAR, szIDName, sizeof(szIDName), &strlen_or_indPtr);</pre>
<div class="note"><span class="notetitle">Note:</span> If
you use this with Visual Basic, it is recommended that you use an array of
Byte data type in place of String data types.</div>
</dd>
<dt class="dlterm">SQLFetch</dt>
<dd>Each time <strong>SQLFetch</strong> is called, the driver fetches the next row.
Bound columns are stored in the locations specified. Data for unbound columns
may be retrieved using <strong>SQLGetData</strong>. <div class="p">In C, this statement is coded:
<pre>rc = SQLFetch(hstmt);</pre>
</div>
<p>Visual Basic does not directly support
pointers or fixed memory location ANSI character null-terminated strings.
For this reason, it is best to use another method to bind Character and Binary
parameters. One method is to convert Visual Basic String data types to/from
an array of Byte data types and bind the array of Byte. Another method is
to use the <strong>SQLGetData</strong> function instead of <strong>SQLBindCol</strong>.</p>
</dd>
<dt class="dlterm">SQLGetData</dt>
<dd>Retrieves data for unbound columns after a fetch. In this example, three
columns are returned and <strong>SQLGetData</strong> is used to move them to the correct
storage location. <p>In C, this statement is coded: </p>
<pre>SQLCHAR szTheName[16], szCredit[2];
float iDiscount, iTax;
rc = SQLFetch(hstmt);
rc = SQLGetData(hstmt, 1, SQL_C_CHAR, szTheName, 16, &strlen_or_indPtr);
rc = SQLGetData(hstmt, 2, SQL_C_FLOAT, &iDiscount, sizeof(float), &indPtr);
rc = SQLGetData(hstmt, 3, SQL_C_CHAR, szCredit, 2, &strlen_or_indPtr);
rc = SQLGetData(hstmt, 4, SQL_C_FLOAT, &iTax, sizeof(float), &indPtr);
</pre>
<p>In Visual Basic, this statement is coded: </p>
<pre> rc = SQLFetch(hStmt)
If rc = SQL_NO_DATA_FOUND Then
Call DisplayWarning("No record found!")
rc = SQLCloseCursor(hStmt)
If rc <> SQL_SUCCESS Then
Call DspSQLDiagRec(SQL_HANDLE_STMT, hStmt, "Close cursor failed.")
End If
Else
' Reset lcbBuffer for the call to SQLGetData
lcbBuffer = 0
'Get part ID from the fetched record
rc = SQLGetData(hStmt, 1, SQL_C_LONG, _
lPartIDReceived, Len(lPartIDReceived), lcbBuffer)
If rc <> SQL_SUCCESS And rc <> SQL_SUCCESS_WITH_INFO Then _
Call DspSQLDiagRec(SQL_HANDLE_STMT, hStmt, _
"Problem getting data for PartID column")
'Get part description from the fetched record
rc = SQLGetData(hStmt, 2, SQL_C_CHAR, _
szDescription(0), 257, lcbBuffer)
If rc <> SQL_SUCCESS And rc <> SQL_SUCCESS_WITH_INFO Then _
Call DspSQLDiagRec(SQL_HANDLE_STMT, hStmt, _
"Problem getting data for PartDescription column")
'Get part provider from the fetched record
rc = SQLGetData(hStmt, 3, SQL_C_CHAR, _
szProvider(0), 257, lcbBuffer)
If rc <> SQL_SUCCESS And rc <> SQL_SUCCESS_WITH_INFO Then _
Call DspSQLDiagRec(SQL_HANDLE_STMT, hStmt, _
"Problem getting data for PartProvider column")
Call DisplayMessage("Record found!")
rc = SQLCloseCursor(hStmt)
If rc <> SQL_SUCCESS Then _
Call DspSQLDiagRec(SQL_HANDLE_STMT, hStmt, "Close cursor failed.")
End If</pre>
</dd>
</dl>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="rzaikodbcapiinfo.htm" title="Identify the files required to build an ODBC application.">Files required to build an ODBC application</a></div>
</div>
</div>
</body>
</html>