I have tables created with
CREATE TABLE COUNTRY (NAME CHAR(16) PRIMARY KEY)
CREATE TABLE PERSON (NAME CAHR(32) PRIMARY KEY,
CITIZENSHIP CHAR(16) CONSTRAINT CY_FK REFERENCES COUNTRY (NAME))
So how can I get Table.Column ( COUNTRY.NAME
) reference of the foreign key after I've performed SELECT
query on PERSON
table? Is it possible to do via JDBC ResultSet , ResultSetMetaData or something alike?
In fact, I need to know:
Well, I did SELECT
on SYS.SYSCONSTRAINTS
but there are only types of constraints ('P', 'F', etc) but no Referenced Tables' names.
I send queries to the Database via JDBC
PreparedStatement stmtDerbyDb = DriverManager.getConnection(dbConnectString).prepareStatement("SELECT * FROM \"" + dbTableOrView + "\"");
ResultSet rsltDerbyDb = stmtDerbyDb.executeQuery();
ResultSetMetaData rsmdDerbyDb = rsltDerbyDb.getMetaData();
...
All the variables stmtDerbyDb , rsltDerbyDb , rsmdDerbyDb are used in further code. I need to know: is it possible to fetch Foreign Key constraints from dbTableOrView via JDBC or shall I query SYS.*
system tables somehow?
Possible decision:
...
Connection connTableView = DriverManager.getConnection("jdbc:Derby:database_name:create=false");
DatabaseMetaData dbmdTableView = connTableView.getMetaData();
ResultSet rsltTableConstraints = dbmdTableView.getImportedKeys(null, null, "PERSON");
PreparedStatement prstTableContents = connTableView.prepareStatement("SELECT * FROM PERSON");
ResultSet rsltTableContents = prstTableContents.executeQuery();
...
buildTableView(rsltTableContents);
rsltTableContents.close();
...
while (rsltTableConstraints.next()) {
PreparedStatement prstConstraints = connTableView.prepareStatement("SELECT " + rsltTableConstraints.getString("PKCOLUMN_NAME") + " FROM " + rsltTableConstraints.getString("PKTABLE_NAME"));
ResultSet rsltConstraintsForCol = prstConstraints.execute();
...
setColumnConstraints(rsltConstraintsForCol, rsltTableConstraints.getString("FKCOLUMN_NAME"));
...
rsltConstraintForCol.close();
prstConstraints.close();
}
...
Which is supposed to be used as ComboBox
dropdowns with constraints per column (with FK of course).
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.