Java 如何从CassandraJDBCResultSet中获取列名?
将CQL语法与cassandra jdbc驱动程序一起使用。。。。 这不起作用,只需获取空字符串:Java 如何从CassandraJDBCResultSet中获取列名?,java,cassandra,Java,Cassandra,将CQL语法与cassandra jdbc驱动程序一起使用。。。。 这不起作用,只需获取空字符串: PreparedStatement pstmt = conn.prepareStatement("select * from myCF"); ResultSet rset = pstmt.executeQuery(); ResultSetMetaData rsmd = rset.getMetaData(); int cols = rsmd.getCo
PreparedStatement pstmt = conn.prepareStatement("select * from myCF");
ResultSet rset = pstmt.executeQuery();
ResultSetMetaData rsmd = rset.getMetaData();
int cols = rsmd.getColumnCount();
pset.next();
print rsmd.getColumnName(0);
print pset.getString(0);
...
显然,每行我都要用“展开”之类的东西。。。
当您不知道列名时,请发布完整示例。好的,这就是有效的方法:
ResultSet res = pstmt.executeQuery();
CassandraResultSet crs = res.unwrap(CassandraResultSet.class);
crs.next() ;
ResultSetMetaData rsmd = crs.getMetaData();
cols = rsmd.getColumnCount();
for(int i=1 ; i <= cols ; i++) {
String colNm = rsmd.getColumnName(i);
String colVal = null;
String colType = rsmd.getColumnTypeName(i);
if (colType.equals("JdbcLong")) {
colVal = "" + crs.getLong(i);
} else if (colType.equals("JdbcInteger")) {
colVal = "" + crs.getInt(i);
} else {
colVal = crs.getString(i);
NOTE: you wont be able to understand your column names and values unless
you set the Cassandra Type hints via cassandra-cli. To have a schema like below
where all un-referenced column types are UTF8Type:
CREATE COLUMN FAMILY MyColFam WITH key_validation_class=UTF8Type
AND default_validation_class=UTF8Type AND comparator=UTF8Type
AND column_metadata = [
{column_name: an_integer_column, validation_class: IntegerType}
{column_name: a_long_column, validation_class: LongType}
];