This function retrieves the primary key of a table from the database and sends this to the client. If a table has a primary key, AOLserver can perform row updates and deletes. If the best-row-id operation is successful, this function should call Ns_PdSendString with an OK_STATUS. If a best-row-id is found then call Ns_PdSendString with the column name; otherwise, call Ns_PdSendString with NO_BESTROWID. On failure this function should return an exception code with Ns_PdSendException.
/* Things italicized would be your DBMS-specific structures and calls. */
#define MAX_COLUMN_NAME 1024
/* This would be a SQL statement to get the primary key */
#define SQL_FINDKEY /* ... */
void
Ns_PdDbBestRowId(void *handle, char *tableName) {
DBMSState *state = (DBMSState *)handle;
Ns_PdRowInfo *bindRowInfo, *getRowInfo;
static char tableColName[] = "name";
char columnName[MAX_COLUMN_NAME];
int i;
int done = 0;
int status = NS_ERROR;
int getRowRet;
Ns_PdLog(Trace, "bestrowid(%s):", tableName);
columnName[0] = '\0';
/* query for a primary key first */
sprintf(state->sqlbuf, SQL_FINDKEY, tableName, "key1", tableName);
for (i = 0; !done && (i DBMSExec(state, state->sqlbuf)) == DB_ROWS) {
if ((bindRowInfo = DBMSBindRow(state)) != NULL) {
char *itemVal;
int itemSize;
int nameIndex;
if ((getRowInfo = Ns_PdNewRowInfo(Ns_PdGetRowInfoNumColumns(bindRowInfo))) != NULL) {
status = NS_OK;
if ((getRowRet = DBMSGetRow(state, getRowInfo)) == NS_OK) {
if ((nameIndex = Ns_PdFindRowInfoValue(bindRowInfo, tableColName, strlen(tableColName))) == -1 ) {
Ns_PdLog(Error, "DbBestRowId: NULL \"%s\" column in %s table, %s key.", tableColName, tableName, i==0 ? "primary" : "secondary");
} else {
Ns_PdGetRowInfoItem(getRowInfo, nameIndex, &itemVal, &itemSize);
strcpy(columnName, itemVal);
}
} else {
if (i == 0) { /* if first try */
if (getRowRet != DB_END_DATA) {
DBMSCancel(state);
}
/* no primary key was found so look for a secondary key */
sprintf(state->sqlbuf, SQL_FINDKEY, tableName, "key2", tableName);
done = 0;
} else { /* secondary key failed */
Ns_PdLog(Trace, "DbBestRowId: Primary and secondary key search failed.");
strcpy(columnName, NO_BESTROWID);
}
}
Ns_PdFreeRowInfo(getRowInfo, 0);
}
Ns_PdFreeRowInfo(bindRowInfo, 1);
}
}
DBMSCancel(state);
if (status == NS_ERROR) {
Ns_PdSendException(state->exceptionCode, state->exceptionMsg);
} else {
Ns_PdSendString(OK_STATUS);
Ns_PdSendString(columnName);
}
}
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