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);
HSQLDB-Specific Information:
HSQLDB supports a subset of theResultSetMetaData interface.
The JDBC specification for ResultSetMetaData is in part very
vague. This causes potential incompatibility between interpretations of the
specification as realized in different JDBC driver implementations. As such,
deciding to what degree reporting ResultSetMetaData is accurate has been
considered very carefully. Hopefully, the design decisions made in light of
these considerations have yielded precisely the subset of full
ResultSetMetaData support that is most commonly needed and that is most
important, while also providing, under the most common use-cases, the
fastest access with the least overhead and the best compromise between
speed, accuracy, jar-footprint and retention of JDBC resources.
(fredt@users)
(campbell-burnet@users)
JDBCStatement#executeQuery, JDBCStatement#getResultSet, java.sql.ResultSetMetaData
| Modifier and Type | Field and Description |
|---|---|
| private int | |
| private ResultMetaData | |
| private boolean | |
| private boolean | useColumnName
Whether to use the underlying column name or label when reporting getColumnName(). |
| Access | Constructor and Description |
|---|---|
| pack-priv | JDBCResultSetMetaData(ResultMetaData
the ResultMetaData object from which to construct a new
JDBCResultSetMetaData object meta, boolean isUpdatable, boolean isInsertable, JDBCConnection conn)Constructs a new JDBCResultSetMetaData object from the specified object. |
| Modifier and Type | Method and Description |
|---|---|
| private void | checkColumn(int
index of column to check column)Performs an internal check for column index validity. |
| public String | Returns: the name of the catalog for the table in which the given column appears or "" if not applicablethe first column is 1, the second is 2, ... column)Implements java. Gets the designated column's table's catalog name. |
| public String | Returns: the fully-qualified name of the class in the Java programming language that would be used by the methodResultSet.getObject to retrieve the value in the specified
column. This is the class name used for custom mapping.the first column is 1, the second is 2, ... column)Implements java. Returns the fully-qualified name of the Java class whose instances
are manufactured if the method |
| public int | Returns: the number of columnsImplements java. Returns the number of columns in this |
| public int | Returns: the normal maximum number of characters allowed as the width of the designated columnthe first column is 1, the second is 2, ... column)Implements java. Indicates the designated column's normal maximum width in characters. |
| public String | Returns: the suggested column titlethe first column is 1, the second is 2, ... column)Implements java. Gets the designated column's suggested title for use in printouts and displays. |
| pack-priv JDBCColumnMetaData | |
| public String | Returns: column namethe first column is 1, the second is 2, ... column)Implements java. Get the designated column's name. |
| public int | Returns: SQL type from java.sql.Typesthe first column is 1, the second is 2, ... column)Implements java. Retrieves the designated column's SQL type. |
| public String | Returns: type name used by the database. If the column type is a user-defined type, then a fully-qualified type name is returned.the first column is 1, the second is 2, ... column)Implements java. Retrieves the designated column's database-specific type name. |
| public int | Returns: precisionthe first column is 1, the second is 2, ... column)Implements java. Get the designated column's specified column size. |
| public int | Returns: scalethe first column is 1, the second is 2, ... column)Implements java. Gets the designated column's number of digits to right of the decimal point. |
| public String | Returns: schema name or "" if not applicablethe first column is 1, the second is 2, ... column)Implements java. Get the designated column's table's schema. |
| public String | Returns: table name or "" if not applicablethe first column is 1, the second is 2, ... column)Implements java. Gets the designated column's table name. |
| pack-priv void | init(ResultMetaData
the ResultMetaData object from which to initialize this
JDBCResultSetMetaData object meta, JDBCConnection the JDBCConnection conn)Initializes this JDBCResultSetMetaData object from the specified Result and HsqlProperties objects. |
| public boolean | Returns: true if so; false otherwisethe first column is 1, the second is 2, ... column)Implements java. Indicates whether the designated column is automatically numbered. |
| public boolean | Returns: true if so; false otherwisethe first column is 1, the second is 2, ... column)Implements java. Indicates whether a column's case matters. |
| public boolean | Returns: true if so; false otherwisethe first column is 1, the second is 2, ... column)Implements java. Indicates whether the designated column is a cash value. |
| public boolean | Returns: true if so; false otherwisethe first column is 1, the second is 2, ... column)Implements java. Indicates whether a write on the designated column will definitely succeed. |
| public int | Returns: the nullability status of the given column; one ofcolumnNoNulls,
columnNullable or columnNullableUnknownthe first column is 1, the second is 2, ... column)Implements java. Indicates the nullability of values in the designated column. |
| public boolean | Returns: true if so; false otherwisethe first column is 1, the second is 2, ... column)Implements java. Indicates whether the designated column is definitely not writable. |
| public boolean | Returns: true if so; false otherwisethe first column is 1, the second is 2, ... column)Implements java. Indicates whether the designated column can be used in a where clause. |
| public boolean | Returns: true if so; false otherwisethe first column is 1, the second is 2, ... column)Implements java. Indicates whether values in the designated column are signed numbers. |
| public boolean | Returns: true if this implements the interface or directly or indirectly wraps an object that does.a Class defining an interface. iface)Implements java. Returns true if this either implements the interface argument or is directly or indirectly a wrapper for an object that does. |
| public boolean | Returns: true if so; false otherwisethe first column is 1, the second is 2, ... column)Implements java. Indicates whether it is possible for a write on the designated column to succeed. |
| public String | Returns: a string representation of the object.Overrides java. Returns a string representation of the object. |
| private Type | |
| public <T> T | Returns: an object that implements the interface. May be a proxy for the actual implementing object.A Class defining an interface that the result must implement. iface)Implements java. Returns an object that implements the given interface to allow access to non-standard methods, or standard methods not exposed by the proxy. |
| columnCount | back to summary |
|---|---|
| private int columnCount | |
| resultMetaData | back to summary |
|---|---|
| private ResultMetaData resultMetaData | |
| translateTTIType | back to summary |
|---|---|
| private boolean translateTTIType | |
| useColumnName | back to summary |
|---|---|
| private boolean useColumnName Whether to use the underlying column name or label when reporting getColumnName(). | |
| JDBCResultSetMetaData | back to summary |
|---|---|
| pack-priv JDBCResultSetMetaData(ResultMetaData meta, boolean isUpdatable, boolean isInsertable, JDBCConnection conn) throws SQLException Constructs a new JDBCResultSetMetaData object from the specified object.
| |
| checkColumn | back to summary |
|---|---|
| private void checkColumn(int column) throws SQLException Performs an internal check for column index validity.
| |
| getCatalogName | back to summary |
|---|---|
| public String getCatalogName(int column) throws SQLException Implements java. Gets the designated column's table's catalog name. HSQLDB-Specific Information: From 2.0, HSQLDB returns the name of the catalog. The default name is PUBLIC. This value can be changed for the database using an SQL command.HSQLDB supports use of catalog qualification in DLL or DML when it is allowed by the Standard. However, not all clients respect the SQL Standard and may use a catalog qualifier in a context where it is not supported by the Standard.
For greater detail, see discussion at:
| |
| getColumnClassName | back to summary |
|---|---|
| public String getColumnClassName(int column) throws SQLException Implements java. Returns the fully-qualified name of the Java class whose instances
are manufactured if the method HSQLDB-Specific Information: HSQLDB 2.0 fully supports this feature.For columns of type OTHER, there is no specific class name and java.lang.Object is returned.
| |
| getColumnCount | back to summary |
|---|---|
| public int getColumnCount() throws SQLException Implements java. Returns the number of columns in this
| |
| getColumnDisplaySize | back to summary |
|---|---|
| public int getColumnDisplaySize(int column) throws SQLException Implements java. Indicates the designated column's normal maximum width in characters. HSQLDB-Specific Information: HSQLDB 2.0 fully supports this feature.The current calculation follows these rules:
| |
| getColumnLabel | back to summary |
|---|---|
| public String getColumnLabel(int column) throws SQLException Implements java. Gets the designated column's suggested title for use in printouts and
displays. The suggested title is usually specified by the SQL HSQLDB-Specific Information: In HSQLDB, aResultSet column label is determined using the
following order of precedence:
| |
| getColumnMetaData | back to summary |
|---|---|
| pack-priv JDBCColumnMetaData getColumnMetaData(int i) | |
| getColumnName | back to summary |
|---|---|
| public String getColumnName(int column) throws SQLException Implements java. Get the designated column's name. HSQLDB-Specific Information: In HSQLDB, a ResultSet column name is determined using the following order of precedence:
If the
| |
| getColumnType | back to summary |
|---|---|
| public int getColumnType(int column) throws SQLException Implements java. Retrieves the designated column's SQL type. HSQLDB-Specific Information: This reports the SQL type code of the column. For time and timestamp types that are WITH TIME ZONE, the values as the SQL Standard CLI codes.
| |
| getColumnTypeName | back to summary |
|---|---|
| public String getColumnTypeName(int column) throws SQLException Implements java. Retrieves the designated column's database-specific type name.
| |
| getPrecision | back to summary |
|---|---|
| public int getPrecision(int column) throws SQLException Implements java. Get the designated column's specified column size. For numeric data, this is the maximum precision. For character data, this is the [maximum] length in characters. For datetime datatypes, this is the [maximum] length in characters of the String representation (assuming the maximum allowed precision of the fractional seconds component). For binary data, this is the [maximum] 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. HSQLDB-Specific Information: HSQLDB 2.0 reports the correct length or precision for all columns. For DOUBLE, the binary precision of 64 is returned, while for other numeric types the decimal precision is returned.
| |
| getScale | back to summary |
|---|---|
| public int getScale(int column) throws SQLException Implements java. 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. HSQLDB-Specific Information: HSQLDB 2.0 reports the correct scale for all columns.For datetime and interval types such as Timestamp or Time, the fractional second precision is reported. The reported scale for INTEGER, BIGINT and DOUBLE is 0.
| |
| getSchemaName | back to summary |
|---|---|
| public String getSchemaName(int column) throws SQLException Implements java. Get the designated column's table's schema. HSQLDB-Specific Information: Since 1.8.0.x, HSQLDB implements standard SQL SCHEMA support; this method returns the actual schema of the column's table. Columns generated in queries have no schema name.
| |
| getTableName | back to summary |
|---|---|
| public String getTableName(int column) throws SQLException Implements java. Gets the designated column's table name.
| |
| init | back to summary |
|---|---|
| pack-priv void init(ResultMetaData meta, JDBCConnection conn) throws SQLException Initializes this JDBCResultSetMetaData object from the specified Result and HsqlProperties objects.
| |
| isAutoIncrement | back to summary |
|---|---|
| public boolean isAutoIncrement(int column) throws SQLException Implements java. Indicates whether the designated column is automatically numbered. HSQLDB-Specific Information: HSQLDB 2.0 fully supports SQL Standard features T174 and T176 that define identity column support.However, it must be stated here that contrary to the generic documentation previous to the JDBC4 specification, HSQLDB automatically numbered columns (IDENTITY columns, in HSQLDB parlance) are not read-only. In fact, the generic documentation previous to the JDBC4 specification seems to contradict the general definition of what, at minimum, an auto-increment column is: Simply, an auto-increment column is one that guarantees it has a autogenerated value after a successful insert or update operation, even if no value is supplied, or DEFAULT is specified.
| |
| isCaseSensitive | back to summary |
|---|---|
| public boolean isCaseSensitive(int column) throws SQLException Implements java. Indicates whether a column's case matters. HSQLDB-Specific Information: HSQLDB 1.7.1 did not report this value accurately.Starting with 1.7.2, this feature is better supported. This method returns true for any column whose data type is a character type, with the exception of VARCHAR_IGNORECASE for which it returns false. It also returns false for any column whose data type is a not a character data type.
| |
| isCurrency | back to summary |
|---|---|
| public boolean isCurrency(int column) throws SQLException Implements java. Indicates whether the designated column is a cash value. HSQLDB-Specific Information: HSQLDB 2.0 fully supports this feature and returns true for NUMERIC and DECIMAL columns.
| |
| isDefinitelyWritable | back to summary |
|---|---|
| public boolean isDefinitelyWritable(int column) throws SQLException Implements java. Indicates whether a write on the designated column will definitely succeed. HSQLDB-Specific Information: From 2.0 this method returns false if the ResultSet is not updatable or the column in question is not updatable.
| |
| isNullable | back to summary |
|---|---|
| public int isNullable(int column) throws SQLException Implements java. Indicates the nullability of values in the designated column. HSQLDB-Specific Information: HSQLDB 2.2 fully supports this feature.
To determine the nullable status of a table column in isolation from ResultSetMetaData and in a DBMS-independent fashion, the DatabaseMetaData.getColumns() method can be invoked with the appropriate filter values and the result should be inspected at the position described in the DatabaseMetaData.getColumns() API documentation.
| |
| isReadOnly | back to summary |
|---|---|
| public boolean isReadOnly(int column) throws SQLException Implements java. Indicates whether the designated column is definitely not writable. HSQLDB-Specific Information: From 2.0 this method returns true if the ResultSet is not updatable or the column in question is not updatable.
| |
| isSearchable | back to summary |
|---|---|
| public boolean isSearchable(int column) throws SQLException Implements java. Indicates whether the designated column can be used in a where clause. HSQLDB-Specific Information: HSQLDB 2.0 handles this differently from previous versions.If the column in question is a database table or view column, and the type of the column allows searching, then returns true, otherwise false.
| |
| isSigned | back to summary |
|---|---|
| public boolean isSigned(int column) throws SQLException Implements java. Indicates whether values in the designated column are signed numbers. HSQLDB-Specific Information: HSQLDB 2.0 fully supports this feature.
| |
| isWrapperFor | back to summary |
|---|---|
| public boolean isWrapperFor(Class<?> iface) throws SQLException Implements java. Returns true if this either implements the interface argument or is directly or indirectly a wrapper
for an object that does. Returns false otherwise. If this implements the interface then return true,
else if this is a wrapper then return the result of recursively calling
| |
| isWritable | back to summary |
|---|---|
| public boolean isWritable(int column) throws SQLException Implements java. Indicates whether it is possible for a write on the designated column to succeed. HSQLDB-Specific Information: From 2.0 this method returns false if the ResultSet is not updatable or the column in question is not updatable.
| |
| toString | back to summary |
|---|---|
| public String toString() Overrides java. Returns a string representation of the object.
The string consists of the name of the class of which the
object is an instance, the at-sign character `
| |
| translateType | back to summary |
|---|---|
| private Type translateType(Type type) Translates an INTERVAL type to VARCHAR. Removes time zone from datetime types. | |
| unwrap | back to summary |
|---|---|
| public <T> T unwrap(Class<T> iface) throws SQLException Implements java. Returns an object that implements the given interface to allow access to
non-standard methods, or standard methods not exposed by the proxy.
If the receiver implements the interface then the result is the receiver
or a proxy for the receiver. If the receiver is a wrapper
and the wrapped object implements the interface then the result is the
wrapped object or a proxy for the wrapped object. Otherwise return the
result of calling
| |