Listing All Culumns - getColumns()

JDBC for SQL Server - Herong's Tutorial Examples

∟Microsoft JDBC Driver - DatabaseMetaData Object

∟Listing All Culumns - getColumns()

This section describes how to get a list of all columns in a table or a view through the DatabaseMetaData object.

If you want list all columns in a table, you can use the DatabaseMetaData method: getColumns(). Input parameters are:

catalog - a catalog name; must match the catalog name as it is stored in the database; "" retrieves those without a catalog; null means that the catalog name should not be used to narrow the search
schemaPattern - a schema name pattern; must match the schema name as it is stored in the database; "" retrieves those without a schema; null means that the schema name should not be used to narrow the search
tableNamePattern - a table name pattern; must match the table name as it is stored in the database
columnNamePattern - a column name pattern; must match the column name as it is stored in the database

The output is captured in a ResultSet object with the following fields:

TABLE_CAT String => table catalog (may be null)
TABLE_SCHEM String => table schema (may be null)
TABLE_NAME String => table name
COLUMN_NAME String => column name
DATA_TYPE int => SQL type from java.sql.Types
TYPE_NAME String => Data source dependent type name, for a UDT the type name is fully qualified
COLUMN_SIZE int => column size.
DECIMAL_DIGITS int => the number of fractional digits. Null is returned for data types where DECIMAL_DIGITS is not applicable.
NULLABLE int => is NULL allowed.

The following sample program displays all columns in the Customer table:

/* ListColumns.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.sql.*;
public class ListColumns {
  public static void main(String [] args) {
    Connection con = null;
    try {

      con = DriverManager.getConnection(
          "jdbc:sqlserver://localhost\\SQLEXPRESS;"
        + "user=herong;password=T0pSecret;"
        + "database=AdventureWorks2019");

      DatabaseMetaData meta = con.getMetaData();
      ResultSet res = meta.getColumns(null, null, "Customer", null);
      System.out.println("List of columns: ");
      while (res.next()) {
         System.out.println(
           "  "+res.getString("TABLE_SCHEM")
           + ", "+res.getString("TABLE_NAME")
           + ", "+res.getString("COLUMN_NAME")
           + ", "+res.getString("TYPE_NAME")
           + ", "+res.getInt("COLUMN_SIZE")
           + ", "+res.getInt("NULLABLE"));
      }
      res.close();

      con.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

If you run this program, you will get:

herong> java -cp .;mssql-jdbc-9.4.1.jre16.jar ListColumns.java

List of columns:
  Sales, Customer, CustomerID, int identity, 10, 0
  Sales, Customer, PersonID, int, 10, 1
  Sales, Customer, StoreID, int, 10, 1
  Sales, Customer, TerritoryID, int, 10, 1
  Sales, Customer, AccountNumber, varchar, 10, 0
  Sales, Customer, rowguid, uniqueidentifier, 36, 0
  Sales, Customer, ModifiedDate, datetime, 23, 0