ParameterMetaData

AI-generated Key Takeaways

• ParameterMetaData provides information about the types and properties of parameters in a PreparedStatement.

• It allows you to retrieve details like parameter count, SQL type, nullability, and precision.

• The data returned by ParameterMetaData may depend on the driver and may not be available until after the PreparedStatement is executed.

• Constants are defined for parameter modes (IN, INOUT, OUT) and nullability.

• Drivers may not fully support this functionality for CallableStatement objects.

public interface ParameterMetaData implements 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.

Constant Summary

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

Public Method Summary

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

Inherited Method Summary

From interface java.sql.Wrapper

abstract boolean	isWrapperFor(Class<?> iface) Returns true if this either implements the interface argument or is directly or indirectly a wrapper for an object that does.
abstract <T> T	unwrap(Class<T> iface) Returns an object that implements the given interface to allow access to non-standard methods, or standard methods not exposed by the proxy.

Constants

public static final int parameterModeIn

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

Constant Value: 1

public static final int parameterModeInOut

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

Constant Value: 2

public static final int parameterModeOut

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

Constant Value: 4

public static final int parameterModeUnknown

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

Constant Value: 0

public static final int parameterNoNulls

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

Constant Value: 0

public static final int parameterNullable

The constant indicating that a parameter will allow NULL values.

Constant Value: 1

public static final int parameterNullableUnknown

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

Constant Value: 2

Public Methods

public abstract String getParameterClassName (int param)

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

public abstract int getParameterCount ()

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

public abstract int getParameterMode (int param)

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

public abstract int getParameterType (int param)

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

See Also

• Types

public abstract String getParameterTypeName (int param)

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

public abstract int getPrecision (int param)

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

public abstract int getScale (int param)

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

public abstract int isNullable (int param)

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

public abstract boolean isSigned (int param)

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