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First commit for the progressive adoption of ADODB's SelectLimit() function

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in order to support LIMIT clauses in a cross-db compatible way.
Changes don't affect old sentences at all (all them would be changed soon too).
This commit is contained in:
stronk7 2006-08-20 09:37:56 +00:00
parent 36647b9fbb
commit 293bccd539
1 changed files with 29 additions and 10 deletions
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39
lib/dmllib.php
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@ -399,20 +399,32 @@ function get_record_sql($sql, $expectmultiple=false, $nolimit=false) {
global $CFG; global $CFG;
/// Default situation
$limitfrom = 0; /// Number of records to skip
$limitnum = 1; /// Number of records to retrieve
/// Only a few uses of the 2nd and 3rd parameter have been found
/// I think that we should avoid to use them completely, one
/// record is one record, and everything else should return error.
/// So the proposal is to change all the uses, (4-5 inside Moodle
/// Core), drop them from the definition and delete the next two
/// "if" sentences. (eloy, 2006-08-19)
if ($nolimit) { if ($nolimit) {
$limit = ''; $limitfrom = 0;
$limitnum = 0;
} else if ($expectmultiple) { } else if ($expectmultiple) {
$limit = ' LIMIT 1'; $limitfrom = 0;
$limitnum = 1;
} else if (isset($CFG->debug) && $CFG->debug > 7) { } else if (isset($CFG->debug) && $CFG->debug > 7) {
// Debugging mode - don't use a limit of 1, but do change the SQL, because sometimes that // Debugging mode - don't use a limit of 1, but do change the SQL, because sometimes that
// causes errors, and in non-debug mode you don't see the error message and it is // causes errors, and in non-debug mode you don't see the error message and it is
// impossible to know what's wrong. // impossible to know what's wrong.
$limit = ' LIMIT 100'; $limitfrom = 0;
} else { $limitnum = 100;
$limit = ' LIMIT 1';
} }
if (!$rs = get_recordset_sql($sql . $limit)) { if (!$rs = get_recordset_sql($sql, $limitfrom, $limitnum)) {
return false; return false;
} }
@ -426,7 +438,7 @@ function get_record_sql($sql, $expectmultiple=false, $nolimit=false) {
} else { // Error: found more than one record } else { // Error: found more than one record
notify('Error: Turn off debugging to hide this error.'); notify('Error: Turn off debugging to hide this error.');
notify($sql . $limit); notify($sql . '(with limits ' . $limitfrom . ', ' . $limitnum . ')');
if ($records = $rs->GetAssoc(true)) { if ($records = $rs->GetAssoc(true)) {
notify('Found more than one record in get_record_sql !'); notify('Found more than one record in get_record_sql !');
print_object($records); print_object($records);
@ -580,21 +592,28 @@ function get_recordset_list($table, $field='', $values='', $sort='', $fields='*'
* @uses $CFG * @uses $CFG
* @uses $db * @uses $db
* @param string $sql the SQL select query to execute. * @param string $sql the SQL select query to execute.
* @param int $limitfrom return a subset of records, starting at this point (optional, required if $limitnum is set).
* @param int $limitnum return a subset comprising this many records (optional, required if $limitfrom is set).
* @return mixed an ADODB RecordSet object, or false if an error occured. * @return mixed an ADODB RecordSet object, or false if an error occured.
*/ */
function get_recordset_sql($sql) { function get_recordset_sql($sql, $limitfrom=null, $limitnum=null) {
global $CFG, $db; global $CFG, $db;
if (defined('MDL_PERFDB')) { global $PERF ; $PERF->dbqueries++; }; if (defined('MDL_PERFDB')) { global $PERF ; $PERF->dbqueries++; };
if (!$rs = $db->Execute($sql)) { if ($limitfrom && $limitnum) {
$rs = $db->SelectLimit($sql, $limitnum, $limitfrom);
} else {
$rs = $db->Execute($sql);
}
if (!$rs) {
if (isset($CFG->debug) and $CFG->debug > 7) { if (isset($CFG->debug) and $CFG->debug > 7) {
notify($db->ErrorMsg() .'<br /><br />'. $sql); notify($db->ErrorMsg() .'<br /><br />'. $sql);
} }
if (!empty($CFG->dblogerror)) { if (!empty($CFG->dblogerror)) {
$debug=array_shift(debug_backtrace()); $debug=array_shift(debug_backtrace());
error_log("SQL ".$db->ErrorMsg()." in {$debug['file']} on line {$debug['line']}. STATEMENT: $sql"); error_log("SQL ".$db->ErrorMsg()." in {$debug['file']} on line {$debug['line']}. STATEMENT: $sql with limits ($limitfrom, $limitnum)");
} }
return false; return false;
} }