/**
* ** Returns true if the specified key attribute exists in the table ** @param altIndexName The
* alternate index name, or null to use the primary index ** @param whereKeyType The partial key
* match type ** @return True if the specified key attribute exists in the table, false otherwise
*/
protected boolean _exists(String altIndexName, int whereKeyType)
throws SQLException, DBException {
/* key fields */
boolean usePrimaryKey = StringTools.isBlank(altIndexName);
DBField kfld[] = usePrimaryKey ? this.getKeyFields() : this.getAltKeyFields(altIndexName);
if (ListTools.isEmpty(kfld)) {
throw new DBException("No keys found!");
}
/* check last key for "auto_increment" */
if (whereKeyType == DBWhere.KEY_FULL) {
DBField lastField = kfld[kfld.length - 1];
if (lastField.isAutoIncrement()
&& !this.getFieldValues().hasFieldValue(lastField.getName())) {
// full key requested and last key is auto_increment, which is missing
return false;
}
}
// DBSelect: SELECT <Keys> FROM <TableName> <KeyWhere>
String firstKey = kfld[0].getName();
DBSelect<gDBR> dsel = new DBSelect<gDBR>(this.getFactory());
dsel.setSelectedFields(firstKey);
dsel.setWhere(this._getWhereClause(altIndexName, whereKeyType));
/* get keyed record */
DBConnection dbc = null;
Statement stmt = null;
ResultSet rs = null;
boolean exists = false;
try {
dbc = DBConnection.getDefaultConnection();
stmt = dbc.execute(dsel.toString()); // may throw DBException
rs = stmt.getResultSet();
exists = rs.next();
} catch (SQLException sqe) {
if (sqe.getErrorCode() == DBFactory.SQLERR_TABLE_NOTLOCKED) {
// MySQL: This case has been seen on rare occasions. Not sure what causes it.
Print.logError("SQL Lock Error: " + sqe);
Print.logError("Hackery! Forcing lock on table: " + this.getTableName());
if (DBProvider.lockTableForRead(this.getTableName(), true)) { // may throw DBException
stmt = dbc.execute(dsel.toString()); // may throw SQLException, DBException
rs = stmt.getResultSet(); // SQLException
exists = rs.next(); // SQLException
DBProvider.unlockTables(); // DBException
}
} else {
throw sqe;
}
} finally {
if (rs != null) {
try {
rs.close();
} catch (Throwable t) {
}
}
if (stmt != null) {
try {
stmt.close();
} catch (Throwable t) {
}
}
DBConnection.release(dbc);
}
return exists;
}