ParameterMetaData (Java Platform SE 6) - JDK 5 Documentation v6.0, Java 2 SDK 英文文档

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Java™ Platform
Standard Ed. 6

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java.sql
Interface ParameterMetaData

All Superinterfaces:: Wrapper

public interface ParameterMetaData
extends Wrapper
extends Wrapper

An object that can be used to get information about the types and properties for each parameter marker in a PreparedStatement object. For some queries and driver implementations, the data that would be returned by a ParameterMetaData object may not be available until the PreparedStatement has been executed.

Some driver implementations may not be able to provide information about the types and properties for each parameter marker in a CallableStatement object.

Since:: 1.4

Field Summary

static int parameterModeIn
          The constant indicating that the parameter's mode is IN.

static int parameterModeInOut
          The constant indicating that the parameter's mode is INOUT.

static int parameterModeOut
          The constant indicating that the parameter's mode is OUT.

static int parameterModeUnknown
          The constant indicating that the mode of the parameter is unknown.

static int parameterNoNulls
          The constant indicating that a parameter will not allow NULL values.

static int parameterNullable
          The constant indicating that a parameter will allow NULL values.

static int parameterNullableUnknown
          The constant indicating that the nullability of a parameter is unknown.

Method Summary

String getParameterClassName(int param)
          Retrieves the fully-qualified name of the Java class whose instances should be passed to the method PreparedStatement.setObject.

int getParameterCount()
          Retrieves the number of parameters in the PreparedStatement object for which this ParameterMetaData object contains information.

int getParameterMode(int param)
          Retrieves the designated parameter's mode.

int getParameterType(int param)
          Retrieves the designated parameter's SQL type.

String getParameterTypeName(int param)
          Retrieves the designated parameter's database-specific type name.

int getPrecision(int param)
          Retrieves the designated parameter's specified column size.

int getScale(int param)
          Retrieves the designated parameter's number of digits to right of the decimal point.

int isNullable(int param)
          Retrieves whether null values are allowed in the designated parameter.

boolean isSigned(int param)
          Retrieves whether values for the designated parameter can be signed numbers.

Methods inherited from interface java.sql.Wrapper

isWrapperFor, unwrap

Field Summary
`static int`	`parameterModeIn` The constant indicating that the parameter's mode is IN.
`static int`	`parameterModeInOut` The constant indicating that the parameter's mode is INOUT.
`static int`	`parameterModeOut` The constant indicating that the parameter's mode is OUT.
`static int`	`parameterModeUnknown` The constant indicating that the mode of the parameter is unknown.
`static int`	`parameterNoNulls` The constant indicating that a parameter will not allow `NULL` values.
`static int`	`parameterNullable` The constant indicating that a parameter will allow `NULL` values.
`static int`	`parameterNullableUnknown` The constant indicating that the nullability of a parameter is unknown.

Method Summary
`String`	`getParameterClassName(int param)` Retrieves the fully-qualified name of the Java class whose instances should be passed to the method `PreparedStatement.setObject`.
`int`	`getParameterCount()` Retrieves the number of parameters in the `PreparedStatement` object for which this `ParameterMetaData` object contains information.
`int`	`getParameterMode(int param)` Retrieves the designated parameter's mode.
`int`	`getParameterType(int param)` Retrieves the designated parameter's SQL type.
`String`	`getParameterTypeName(int param)` Retrieves the designated parameter's database-specific type name.
`int`	`getPrecision(int param)` Retrieves the designated parameter's specified column size.
`int`	`getScale(int param)` Retrieves the designated parameter's number of digits to right of the decimal point.
`int`	`isNullable(int param)` Retrieves whether null values are allowed in the designated parameter.
`boolean`	`isSigned(int param)` Retrieves whether values for the designated parameter can be signed numbers.

Methods inherited from interface java.sql.Wrapper
`isWrapperFor, unwrap`

Field Detail

parameterNoNulls

static final int parameterNoNulls

The constant indicating that a parameter will not allow NULL values.

See Also:: Constant Field Values

parameterNullable

static final int parameterNullable

The constant indicating that a parameter will allow NULL values.

See Also:: Constant Field Values

parameterNullableUnknown

static final int parameterNullableUnknown

The constant indicating that the nullability of a parameter is unknown.

See Also:: Constant Field Values

parameterModeUnknown

static final int parameterModeUnknown

The constant indicating that the mode of the parameter is unknown.

See Also:: Constant Field Values

parameterModeIn

static final int parameterModeIn

The constant indicating that the parameter's mode is IN.

See Also:: Constant Field Values

parameterModeInOut

static final int parameterModeInOut

The constant indicating that the parameter's mode is INOUT.

See Also:: Constant Field Values

parameterModeOut

static final int parameterModeOut

The constant indicating that the parameter's mode is OUT.

See Also:: Constant Field Values

Method Detail

getParameterCount

int getParameterCount()
                      throws SQLException

Retrieves the number of parameters in the PreparedStatement object for which this ParameterMetaData object contains information.

Returns:: the number of parameters
Throws:: SQLException - if a database access error occurs
Since:: 1.4

isNullable

int isNullable(int param)
               throws SQLException

Retrieves whether null values are allowed in the designated parameter.

Parameters:: param - the first parameter is 1, the second is 2, ...
Returns:: the nullability status of the given parameter; one of ParameterMetaData.parameterNoNulls, ParameterMetaData.parameterNullable, or ParameterMetaData.parameterNullableUnknown
Throws:: SQLException - if a database access error occurs
Since:: 1.4

isSigned

boolean isSigned(int param)
                 throws SQLException

Retrieves whether values for the designated parameter can be signed numbers.

Parameters:: param - the first parameter is 1, the second is 2, ...
Returns:: true if so; false otherwise
Throws:: SQLException - if a database access error occurs
Since:: 1.4

getPrecision

int getPrecision(int param)
                 throws SQLException

Retrieves the designated parameter's specified column size.

The returned value represents the maximum column size for the given parameter. 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:: param - the first parameter is 1, the second is 2, ...
Returns:: precision
Throws:: SQLException - if a database access error occurs
Since:: 1.4

getScale

int getScale(int param)
             throws SQLException

Retrieves the designated parameter's number of digits to right of the decimal point. 0 is returned for data types where the scale is not applicable.

Parameters:: param - the first parameter is 1, the second is 2, ...
Returns:: scale
Throws:: SQLException - if a database access error occurs
Since:: 1.4

getParameterType

int getParameterType(int param)
                     throws SQLException

Retrieves the designated parameter's SQL type.

Parameters:: param - the first parameter is 1, the second is 2, ...
Returns:: SQL type from java.sql.Types
Throws:: SQLException - if a database access error occurs
Since:: 1.4
See Also:: Types

getParameterTypeName

String getParameterTypeName(int param)
                            throws SQLException

Retrieves the designated parameter's database-specific type name.

Parameters:: param - the first parameter is 1, the second is 2, ...
Returns:: type the name used by the database. If the parameter type is a user-defined type, then a fully-qualified type name is returned.
Throws:: SQLException - if a database access error occurs
Since:: 1.4

getParameterClassName

String getParameterClassName(int param)
                             throws SQLException

Retrieves the fully-qualified name of the Java class whose instances should be passed to the method PreparedStatement.setObject.

Parameters:: param - the first parameter 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 PreparedStatement.setObject to set the value in the specified parameter. This is the class name used for custom mapping.
Throws:: SQLException - if a database access error occurs
Since:: 1.4

getParameterMode

int getParameterMode(int param)
                     throws SQLException

Retrieves the designated parameter's mode.

Parameters:: param - the first parameter is 1, the second is 2, ...
Returns:: mode of the parameter; one of ParameterMetaData.parameterModeIn, ParameterMetaData.parameterModeOut, or ParameterMetaData.parameterModeInOut ParameterMetaData.parameterModeUnknown.
Throws:: SQLException - if a database access error occurs
Since:: 1.4