Table

The Java API defines the data form Table to facilitate queries and operations on data.

Creating a Table

Constructor

The constructor of BasicTable is as follows:

public BasicTable(final List<String> colNames, final List<Vector> cols)

Parameters

colNames: Column names of the table.
cols: Data for each column.

Retrieving Table Data via Query

You can directly obtain a table by executing a query.

DBConnection dbConnection = new DBConnection();
DBConnection dbConnection = new DBConnection();
dbConnection.connect(HOST,PORT,USER,PASSWORD);
BasicTable basicTable = (BasicTable) dbConnection.run("select * from loadTable(\"dfs://ramd\",`pt3)");

Usage

You can get all values of a column using the getColumn method, which is defined as follows:
```
// by column index
public Vector getColumn(int index)

// by column name
public Vector getColumn(String name)
```
The return value is a com.xxdb.data.Vector, which can be used to iterate through all data.

You can manipulate the Vector object returned by getColumn to modify the content of the table. For example:

public void test_set_nullvalue() throws IOException {
  try{
      List<String> colNames =  Arrays.asList("cint","cdouble","clong","cfloat","cshort");
      List<Vector> colData = Arrays.asList(new BasicIntVector(1),new BasicDoubleVector(1),new BasicLongVector(1),new BasicFloatVector(1),new BasicShortVector(1));
      BasicTable bt = new BasicTable(colNames,colData);
      bt.getColumn("cint").set(0,new BasicInt(Integer.MIN_VALUE));
      bt.getColumn("cdouble").set(0,new BasicDouble(-Double.MIN_VALUE));
      bt.getColumn("clong").set(0,new BasicLong(Long.MIN_VALUE));
      bt.getColumn("cfloat").set(0,new BasicFloat(-Float.MAX_VALUE));
      bt.getColumn("cshort").set(0,new BasicShort(Short.MIN_VALUE));
      bt.getColumn("cshort").set(0,new BasicShort(Short.MIN_VALUE));
      bt.getColumn("cshort").set(0,new BasicShort(Short.MIN_VALUE));
      assertTrue(((Scalar)bt.getColumn("clong").get(0)).isNull());
  }catch (Exception e){
      e.printStackTrace();
  }
}

If you want to generate each row in JSON format, you can call the getRowJson method. For example:

DBConnection dbConnection = new DBConnection();
dbConnection.connect(HOST, PORT, USER, PASSWORD);
BasicTable basicTable = (BasicTable) dbConnection.run("select * from loadTable(\"dfs://ramd\", `pt3)");
// Get the number of rows
int rows = basicTable.rows();
// Iterate through each row
for (int i = 0; i < rows; i++) {
    System.out.println(basicTable.getRowJson(i));
}