У меня есть база данных с несколькими таблицами, три из которых следующие:
Controllers_Readers
-------------------
ControllerID: Number (Long Integer), Default 0, Indexed (Y, no Duplicated)
ReaderID: Number (Long Integer), Default 0, Indexed (Y, No Duplicates)
Controllers
-----------
ControllerID: Number (Long Integer), Default 0, Indexed (Y, No Duplicates)
Description: Short Text (32)
Name: Short Text (32)
...
Readers
-------
ReaderID: Number (Long Integer), Default 0, Indexed (Y, No Duplicates)
Direction: Number (Long Integer)
Description: Short Text (32)
Name: Short Text (32)
...
У меня есть следующий Java-код, чтобы проверить, существует ли таблица и содержит ли она определенный столбец, на основе этого ответа на вопрос о метаданных таблицы :
/* Use the metadata to check if a table exists and has a specific column */
public static boolean tableHasColumn(Connection con, String tableName, String colName)
throws ClassNotFoundException, SQLException, InstantiationException,
IllegalAccessException
{
boolean exists = false, hasCol = false;
ResultSet rs = null, r = null;
Statement s = null;
try {
DatabaseMetaData dbm = con.getMetaData();
rs = dbm.getTables(null, null, tableName, null);
if (rs.next() && rs.getRow() > -1) {
exists = true;
s = con.createStatement();
r = s.executeQuery("SELECT * FROM " + tableName + " LIMIT 1");
if (r.next()) {
ResultSetMetaData rsmd = r.getMetaData();
for (int col = 1; col < rsmd.getColumnCount(); col++) {
String name = rsmd.getColumnName(col);
logger.debug("Found column \"" + name + "\" in \"" + tableName + "\".");
if (name.equals(colName)) {
hasCol = true;
break;
}
}
}
}
} finally {
if (null != rs) {
try {
rs.close();
} catch (SQLException ex) {
logger.warn(
"Failed to close Resultset to DB while checking if table exists!"
);
}
}
}
logger.debug(
"Table (" + tableName + ") Exists: " + String.valueOf(exists).toUpperCase()
+ "\tHas Column (" + colName + "): " + String.valueOf(hasCol).toUpperCase()
);
return (exists && hasCol);
}
Если указать значения "Controllers_Readers" и "ControllerID" для tableName и colName, соответственно, возвращается значение true. Однако, когда я запускаю следующий запрос, я получаю сообщение об ошибке org.hsqldb.HsqlException: user lacks privilege or object not found: CONTROLLERS_READERS.CONTROLLERID
:
SELECT C.Description AS cName, C.ControllerID AS CID,
D.DirectionText as dName, D.Direction AS dirNum, R.Description AS rName,
R.ReaderID AS RID, AP.Name AS aName, AP.Description as aDescrip, AP.PointID
FROM Controllers AS C, Controllers_Readers AS CR, Readers AS R,
Directions AS D, AccessPoints AS AP, Points_Controllers as PC
WHERE Controllers_Readers.ControllerID = Controllers.ControllerID
AND Readers.ReaderID = Controllers_Readers.ReaderID
AND Directions.Direction = Readers.Direction AND
Points_Controllers.ControllerID = Controllers.ControllerID
AND AccessPoints.PointID = Points_Controllers.PointID
GROUP BY Controllers.Description, Controllers.ControllerID,
Directions.DirectionText, Directions.Direction, Readers.Name,
Readers.Description, Readers.ReaderID, AccessPoints.Name,
AccessPoints.Description, AccessPoints.PointID
ORDER BY Controllers.Description, Controllers.ControllerID,
Directions.DirectionText, Directions.Direction, Readers.Name,
Readers.Description, Readers.ReaderID, AccessPoints.Name,
AccessPoints.Description, AccessPoints.PointID
Соответствующий вывод журнала выглядит следующим образом:
2018-08-30 14:24:35 [DEBUG] db.Locations:35 - Location: LOCAL DB Path: \\sentinel.domain\TempStorage\Me\dbs\Redacted.mdb
2018-08-30 14:24:35 [DEBUG] db.Digger:767 - Connect to DB on path: \\sentinel.domain\TempStorage\Me\dbs\Redacted.mdb
2018-08-30 14:24:35 [INFO ] db.Digger:790 - Connecting to jdbc:ucanaccess:////sentinel.domain/TempStorage/Me/dbs//Redacted.mdb;openExclusive=false;concatNulls=false;ignoreCase=true
2018-08-30 14:24:37 [DEBUG] impl.DatabaseImpl:887 - Finished reading system catalog. Tables: [AccessNumbers, AccessNumbers_Controllers, AccessNumbers_Groups, AccessNumbers_Readers, AccessPoints, Areas, Areas_Controllers, Areas_Points, Areas_Timezones, Controllers, Controllers_Expanders, Controllers_Readers, Directions, Events, Expanders_Readers, Groups, Groups_Areas, Groups_Controllers, Groups_Timezones, Holidays, Points_Controllers, Points_Readers, Points_Timezones, ReaderExpanders, Readers, SelectedAreas, SelectedDates, Sites, Sites_Areas, Status, Storage, Timezones, Transactions, UserInformation, Users] (Db=Redacted.mdb)
2018-08-30 14:25:10 [DEBUG] db.Digger:884 - Found column "ControllerID" in "Controllers_Readers".
2018-08-30 14:25:10 [DEBUG] db.Digger:901 - Table (Controllers_Readers) Exists: TRUE Has Column: TRUE
2018-08-30 14:25:10 [ERROR] db.Digger:1180 - [UcanaccessSQLException]: UCAExc:::4.0.2 user lacks privilege or object not found: CONTROLLERS_READERS.CONTROLLERID
net.ucanaccess.jdbc.UcanaccessSQLException: UCAExc:::4.0.2 user lacks privilege or object not found: CONTROLLERS_READERS.CONTROLLERID
at net.ucanaccess.jdbc.UcanaccessStatement.executeQuery(UcanaccessStatement.java:210)
at db.Digger.loadAllControllerReaders(Digger.java:947)
at db.Digger.main(Digger.java:1177)
Caused by: java.sql.SQLSyntaxErrorException: user lacks privilege or object not found: CONTROLLERS_READERS.CONTROLLERID
at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
at org.hsqldb.jdbc.JDBCStatement.fetchResult(Unknown Source)
at org.hsqldb.jdbc.JDBCStatement.executeQuery(Unknown Source)
at net.ucanaccess.jdbc.UcanaccessStatement.executeQuery(UcanaccessStatement.java:208)
... 2 more
Caused by: org.hsqldb.HsqlException: user lacks privilege or object not found: CONTROLLERS_READERS.CONTROLLERID
at org.hsqldb.error.Error.error(Unknown Source)
at org.hsqldb.error.Error.error(Unknown Source)
at org.hsqldb.ExpressionColumn.checkColumnsResolved(Unknown Source)
at org.hsqldb.QueryExpression.resolve(Unknown Source)
at org.hsqldb.ParserDQL.compileCursorSpecification(Unknown Source)
at org.hsqldb.ParserCommand.compilePart(Unknown Source)
at org.hsqldb.ParserCommand.compileStatements(Unknown Source)
at org.hsqldb.Session.executeDirectStatement(Unknown Source)
at org.hsqldb.Session.execute(Unknown Source)
Примечание: db.Digger и db.Locations являются классами в моем приложении. loadAllControllerReaders - это метод, который выполняет SQL-запрос`.
Выполнение того же запроса к БД через MS Access (Office 365) дает мне набор результатов со значениями в столбцах. Почему uCanAccess / HSQLDB не может сделать то же самое (не удается найти столбец ControllerID в Controllers_Readers)? Как заставить его распознать, что этот столбец существует в таблице?