ResultSetMetaData (Java SE 15 & JDK 15)
Description: declaration: module: java.sql, package: java.sql, interface: ResultSetMetaData
Keywords: java.sql.ResultSetMetaData interface

Module java.sql
Package java.sql

# Interface ResultSetMetaData

All Superinterfaces:
  `Wrapper`

All Known Subinterfaces:
  `RowSetMetaData`

All Known Implementing Classes:
  `RowSetMetaDataImpl`

    public interface ResultSetMetaData
    extends Wrapper

An object that can be used to get information about the types and properties of the columns in a `ResultSet` object. The following code fragment creates the `ResultSet` object rs, creates the `ResultSetMetaData` object rsmd, and uses rsmd to find out how many columns rs has and whether the first column in rs can be used in a `WHERE` clause.

         ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
         ResultSetMetaData rsmd = rs.getMetaData();
         int numberOfColumns = rsmd.getColumnCount();
         boolean b = rsmd.isSearchable(1);

Since:
  1.1

- ## Field Summary

  Fields
  Modifier and Type | Field | Description
  --- | --- | ---
  `static int` | `columnNoNulls` | The constant indicating that a column does not allow `NULL` values.
  `static int` | `columnNullable` | The constant indicating that a column allows `NULL` values.
  `static int` | `columnNullableUnknown` | The constant indicating that the nullability of a column's values is unknown.

- ## Method Summary

  Modifier and Type | Method | Description
  --- | --- | ---
  `String` | `getCatalogName​(int column)` | Gets the designated column's table's catalog name.
  `String` | `getColumnClassName​(int column)` | Returns the fully-qualified name of the Java class whose instances are manufactured if the method `ResultSet.getObject` is called to retrieve a value from the column.
  `int` | `getColumnCount()` | Returns the number of columns in this `ResultSet` object.
  `int` | `getColumnDisplaySize​(int column)` | Indicates the designated column's normal maximum width in characters.
  `String` | `getColumnLabel​(int column)` | Gets the designated column's suggested title for use in printouts and displays.
  `String` | `getColumnName​(int column)` | Get the designated column's name.
  `int` | `getColumnType​(int column)` | Retrieves the designated column's SQL type.
  `String` | `getColumnTypeName​(int column)` | Retrieves the designated column's database-specific type name.
  `int` | `getPrecision​(int column)` | Get the designated column's specified column size.
  `int` | `getScale​(int column)` | Gets the designated column's number of digits to right of the decimal point. 0 is returned for data types where the scale is not applicable.
  `String` | `getSchemaName​(int column)` | Get the designated column's table's schema.
  `String` | `getTableName​(int column)` | Gets the designated column's table name.
  `boolean` | `isAutoIncrement​(int column)` | Indicates whether the designated column is automatically numbered.
  `boolean` | `isCaseSensitive​(int column)` | Indicates whether a column's case matters.
  `boolean` | `isCurrency​(int column)` | Indicates whether the designated column is a cash value.
  `boolean` | `isDefinitelyWritable​(int column)` | Indicates whether a write on the designated column will definitely succeed.
  `int` | `isNullable​(int column)` | Indicates the nullability of values in the designated column.
  `boolean` | `isReadOnly​(int column)` | Indicates whether the designated column is definitely not writable.
  `boolean` | `isSearchable​(int column)` | Indicates whether the designated column can be used in a where clause.
  `boolean` | `isSigned​(int column)` | Indicates whether values in the designated column are signed numbers.
  `boolean` | `isWritable​(int column)` | Indicates whether it is possible for a write on the designated column to succeed.

  ### Methods declared in interface java.sql.Wrapper

  `isWrapperFor, unwrap`

- ## Field Details

  - ### columnNoNulls

    static final int columnNoNulls
    The constant indicating that a column does not allow `NULL` values.
    See Also:
      Constant Field Values

  - ### columnNullable

    static final int columnNullable
    The constant indicating that a column allows `NULL` values.
    See Also:
      Constant Field Values

  - ### columnNullableUnknown

    static final int columnNullableUnknown
    The constant indicating that the nullability of a column's values is unknown.
    See Also:
      Constant Field Values

- ## Method Details

  - ### getColumnCount

    int getColumnCount() throws SQLException
    Returns the number of columns in this `ResultSet` object.
    Returns:
      the number of columns
    Throws:
      `SQLException` - if a database access error occurs

  - ### isAutoIncrement

    boolean isAutoIncrement​(int column) throws SQLException
    Indicates whether the designated column is automatically numbered.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      `true` if so; `false` otherwise
    Throws:
      `SQLException` - if a database access error occurs

  - ### isCaseSensitive

    boolean isCaseSensitive​(int column) throws SQLException
    Indicates whether a column's case matters.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      `true` if so; `false` otherwise
    Throws:
      `SQLException` - if a database access error occurs

  - ### isSearchable

    boolean isSearchable​(int column) throws SQLException
    Indicates whether the designated column can be used in a where clause.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      `true` if so; `false` otherwise
    Throws:
      `SQLException` - if a database access error occurs

  - ### isCurrency

    boolean isCurrency​(int column) throws SQLException
    Indicates whether the designated column is a cash value.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      `true` if so; `false` otherwise
    Throws:
      `SQLException` - if a database access error occurs

  - ### isNullable

    int isNullable​(int column) throws SQLException
    Indicates the nullability of values in the designated column.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      the nullability status of the given column; one of `columnNoNulls`, `columnNullable` or `columnNullableUnknown`
    Throws:
      `SQLException` - if a database access error occurs

  - ### isSigned

    boolean isSigned​(int column) throws SQLException
    Indicates whether values in the designated column are signed numbers.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      `true` if so; `false` otherwise
    Throws:
      `SQLException` - if a database access error occurs

  - ### getColumnDisplaySize

    int getColumnDisplaySize​(int column) throws SQLException
    Indicates the designated column's normal maximum width in characters.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      the normal maximum number of characters allowed as the width of the designated column
    Throws:
      `SQLException` - if a database access error occurs

  - ### getColumnLabel

    String getColumnLabel​(int column) throws SQLException
    Gets the designated column's suggested title for use in printouts and displays. The suggested title is usually specified by the SQL `AS` clause. If a SQL `AS` is not specified, the value returned from `getColumnLabel` will be the same as the value returned by the `getColumnName` method.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      the suggested column title
    Throws:
      `SQLException` - if a database access error occurs

  - ### getColumnName

    String getColumnName​(int column) throws SQLException
    Get the designated column's name.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      column name
    Throws:
      `SQLException` - if a database access error occurs

  - ### getSchemaName

    String getSchemaName​(int column) throws SQLException
    Get the designated column's table's schema.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      schema name or "" if not applicable
    Throws:
      `SQLException` - if a database access error occurs

  - ### getPrecision

    int getPrecision​(int column) throws SQLException
    Get the designated column's specified column size. For numeric data, this is the maximum precision. For character data, this is the length in characters. For datetime datatypes, this is the length in characters of the String representation (assuming the maximum allowed precision of the fractional seconds component). For binary data, this is the length in bytes. For the ROWID datatype, this is the length in bytes. 0 is returned for data types where the column size is not applicable.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      precision
    Throws:
      `SQLException` - if a database access error occurs

  - ### getScale

    int getScale​(int column) throws SQLException
    Gets the designated column's number of digits to right of the decimal point. 0 is returned for data types where the scale is not applicable.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      scale
    Throws:
      `SQLException` - if a database access error occurs

  - ### getTableName

    String getTableName​(int column) throws SQLException
    Gets the designated column's table name.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      table name or "" if not applicable
    Throws:
      `SQLException` - if a database access error occurs

  - ### getCatalogName

    String getCatalogName​(int column) throws SQLException
    Gets the designated column's table's catalog name.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      the name of the catalog for the table in which the given column appears or "" if not applicable
    Throws:
      `SQLException` - if a database access error occurs

  - ### getColumnType

    int getColumnType​(int column) throws SQLException
    Retrieves the designated column's SQL type.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      SQL type from java.sql.Types
    Throws:
      `SQLException` - if a database access error occurs
    See Also:
      `Types`

  - ### getColumnTypeName

    String getColumnTypeName​(int column) throws SQLException
    Retrieves the designated column's database-specific type name.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      type name used by the database. If the column type is a user-defined type, then a fully-qualified type name is returned.
    Throws:
      `SQLException` - if a database access error occurs

  - ### isReadOnly

    boolean isReadOnly​(int column) throws SQLException
    Indicates whether the designated column is definitely not writable.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      `true` if so; `false` otherwise
    Throws:
      `SQLException` - if a database access error occurs

  - ### isWritable

    boolean isWritable​(int column) throws SQLException
    Indicates whether it is possible for a write on the designated column to succeed.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      `true` if so; `false` otherwise
    Throws:
      `SQLException` - if a database access error occurs

  - ### isDefinitelyWritable

    boolean isDefinitelyWritable​(int column) throws SQLException
    Indicates whether a write on the designated column will definitely succeed.
    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      `true` if so; `false` otherwise
    Throws:
      `SQLException` - if a database access error occurs

  - ### getColumnClassName

    String getColumnClassName​(int column) throws SQLException

    Returns the fully-qualified name of the Java class whose instances are manufactured if the method `ResultSet.getObject` is called to retrieve a value from the column. `ResultSet.getObject` may return a subclass of the class returned by this method.

    Parameters:
      `column` - the first column is 1, the second is 2, ...
    Returns:
      the fully-qualified name of the class in the Java programming language that would be used by the method `ResultSet.getObject` to retrieve the value in the specified column. This is the class name used for custom mapping.
    Throws:
      `SQLException` - if a database access error occurs
    Since:
      1.2