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Send system catalog information about a table to the client.
void Ns_PdDbGetTableInfo(void *handle, char *tableName);
This function should retrieve the system catalog information (columns, types, etc.) about a table and send this to the client.
Returning a successful status of DB_ROWS indicates that the SQL query was the type of query that returned rows (e.g., SELECT), rather than a manipulation statement that does not return rows. If the initial SQL select query returns a successful status of DB_ROWS, then this function should:
Ns_PdDbGetTableInfo() describes the table by sending back three columns of data, named "ColName," "ColType," and "NotNull" respectively. These column names are sent to the server with an Ns_PdSendRowInfo() call. Then, each column of the table is described by sending a 3-column row to the server, giving the name, type and nullability of the table's column. Again, Ns_PdSendRowInfo() is used to send this information to the AOL Server. The type is specified as a string (one of the types from Ns_PdDbGetTypes()). The nullability is specified as either the string "t" or "f".
/* Things italicized would be your DBMS-specific structures and
calls. */
/* defined in nspd.h */
typedef struct Ns_PdRowData {
int elSize;
char *elData;
} Ns_PdRowData;
typedef struct Ns_PdRowInfo {
int numColumns;
Ns_PdRowData *rowData;
};
void
Ns_PdDbGetTableInfo(void *handle, char *tableName) {
DBMSState *state = (DBMSState *) handle;
Ns_PdRowInfo *getRowInfo, *bindRowInfo;
int status = NS_ERROR;
int getRowRet;
/* Exec SQL and "select" data from a table */
Ns_PdLog(Trace, "gettableinfo(%s):", tableName);
sprintf(state->sqlbuf,
"select c.column_name, c.column_type, c.column_notnull"
" from columns c, tables t"
" where t.table_name = '%s'"
" and c.column_member = t.table_type;", tableName);
status = DBMDExec(state, state->sqlbuf);
if (status == DB_ROWS) {
if ((bindRowInfo = DBMSBindRow(state)) != NULL) {
getRowInfo =
Ns_PdNewRowInfo(Ns_PdGetRowInfoNumColumns(bindRowInfo));
if (getRowInfo != NULL) {
status = NS_OK;
Ns_PdSendString(OK_STATUS);
Ns_PdSendRowInfo(bindRowInfo); /* sends list of
column names */
while ((getRowRet = DBMSGetRow(handle,
getRowInfo)) == NS_OK) {
/* send row info */
Ns_PdSendRowInfo(getRowInfo);
}
Ns_PdSendData(END_DATA, strlen(END_DATA)); /* NULL
row terminates rows */
if (getRowRet == DB_END_DATA) {
status = NS_OK;
} else {
Ns_PdLog(Error, "GetTableInfo: incomplete data
sent to client (table=%s)",
tableName);
}
/* free the getRowInfo structure when done */
Ns_PdFreeRowInfo(getRowInfo, 0);
}
/* free the bindRowInfo data and structure when done */
Ns_PdFreeRowInfo(bindRowInfo, 1);
}
}
if (status != NS_OK) {
Ns_PdSendException(state->exceptionCode,
state->exceptionMsg);
}
}