[英]How to return the column count, column names, and column types from a specified table in Java?
我有一项家庭作业,要打印出输入给定表的列数、名称和类型。 这是代码:
public void printTableInfo(String tableName) throws DLException{
String catalog = null;
String schemaPattern = null;
String tableNamePattern = tableName;
String columnNamePattern = null;
int columnCount = 0;
String columnName = null;
int columnType = 0;
String columnPrimaryKeys = null;
try {
DatabaseMetaData dbmd = connection.getMetaData();
ResultSet result = dbmd.getColumns(catalog, schemaPattern, tableNamePattern, columnNamePattern);
ResultSetMetaData rsmd = result.getMetaData();
columnCount = rsmd.getColumnCount();
ResultSet primaryKeys = dbmd.getPrimaryKeys(catalog, schemaPattern, tableNamePattern);
while(result.next()) {
columnName = result.getString(4);
columnType = result.getInt(5);
}
while(primaryKeys.next()) {
columnPrimaryKeys = primaryKeys.getString(4);
}
System.out.println("\nColumn count: " + columnCount + ", Column names: " + columnName + ", Column Types: " + columnType + "\nPrimary Keys: " + columnPrimaryKeys);
} catch (SQLException sqle) {
throw new DLException(sqle, "-> Error in processing data printing (SQLException) to the database at printTableInfo() method.");
}
}
但是,当我运行此代码时,它给我的表的列数比它有的多,只有最后一个列名和不正确的列类型数。 我怎样才能使它产生正确的列数,显示所有列名和正确数量的列类型? PS主键部分工作正常。
我想通了,我没有在正确的位置打印。 告我。
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