public final Class DataTypeDescriptor

Runtime INTEGER type that is nullable.

Runtime INTEGER type that is nullable.

Runtime INTEGER type that is not nullable.

Runtime SMALLINT type that is nullable.

Runtime INTEGER type that is not nullable.

Public niladic constructor. Needed for Formatable interface to work.

Constructor for use with numeric types

Parameters

typeId:TypeId

The typeId of the type being described

precision:int

The number of decimal digits.

scale:int

The number of digits after the decimal point.

isNullable:boolean

TRUE means it could contain NULL, FALSE means it definitely cannot contain NULL.

maximumWidth:int

The maximum number of bytes for this datatype

Constructor to use when the caller doesn't know if it is requesting numeric or no-numeric DTD. For instance, when dealing with MAX/MIN aggregrate operators, AggregateNode.bindExpression could be dealing with a character string operand or a numeric operand. The result of MAX/MIN will depend on the type of it's operand. And hence when this constructor gets called by AggregateNode.bindExpression, we don't know what type we are constructing and hence this constructor supports arguments for both numeric and non-numeric types.

Parameters

typeId:TypeId

The typeId of the type being described

precision:int

The number of decimal digits.

scale:int

The number of digits after the decimal point.

isNullable:boolean

TRUE means it could contain NULL, FALSE means it definitely cannot contain NULL.

maximumWidth:int

The maximum number of bytes for this datatype

collationType:int

The collation type of a string data type

collationDerivation:int

Collation Derivation of a string data type

Constructor for use with non-numeric types

Parameters

typeId:TypeId

The typeId of the type being described

isNullable:boolean

TRUE means it could contain NULL, FALSE means it definitely cannot contain NULL.

maximumWidth:int

The maximum number of bytes for this datatype

Constructor for internal uses only. (This is useful when the precision and scale are potentially wider than those in the source, like when determining the dominant data type.)

Parameters

source:DataTypeDescriptor

The DTSI to copy

precision:int

The number of decimal digits.

scale:int

The number of digits after the decimal point.

isNullable:boolean

TRUE means it could contain NULL, FALSE means it definitely cannot contain NULL.

maximumWidth:int

The maximum number of bytes for this datatype

Constructor for internal uses only

Parameters

source:DataTypeDescriptor

The DTSI to copy

isNullable:boolean

TRUE means it could contain NULL, FALSE means it definitely cannot contain NULL.

maximumWidth:int

The maximum number of bytes for this datatype

Check if this type is comparable with the passed type.

Parameters

compareWithDTD:DataTypeDescriptor

the type of the instance to compare with this type.

forEquals:boolean

True if this is an = or != comparison, false otherwise.

cf:ClassFactory

A ClassFactory

Returns:boolean

true if compareWithDTD is comparable to this type, else false.

Compare the collation info on this DTD with the passed DTD. The rules for comparison are as follows (these are as per SQL standard 2003 Section 9.13) 1)If both the DTDs have collation derivation of NONE, then they can't be compared and we return false. 2)If both the DTDs have same collation derivation (which in Derby's case at this point will mean collation derivation of IMPLICIT), then check the collation types. If they match, then return true. If they do not match, then they can't be compared and hence return false. 3)If one DTD has collation derivation of IMPLICIT and other DTD has collation derivation of NONE, then 2 DTDs are comparable using the collation type of DTD with collation derivation of IMPLICIT. Derby does not implement this rule currently and it is being traked as DERBY-2678. Derby's current behavior is to throw an exception if both the DTDs involved in collation operation do not have collation derivation of IMPLICIT. This behavior is a subset of SQL standard. 4)Derby currently does not support collation derivation of EXPLICIT and hence we do not have the code to enforce rules as mentioned in Section 9.13 of SQL spec for collation derivation of EXPLICIT. When we implement collation derivation of EXPLICIT, we should make sure that we follow the rules as specified in the SQL spec for comparability.

Parameters

compareWithDTD:DataTypeDescriptor

compare this DTD's collation info

Returns:boolean

value depends on the algorithm above.

Overrides java.lang.Object.equals.

Compare if two DataTypeDescriptors are exactly the same

Parameters

other:Object

the type to compare to.

Returns:boolean

Doc from java.lang.Object.equals.

true if this object is the same as the obj argument; false otherwise.

Get the estimated memory usage for this type descriptor.

Get a descriptor that corresponds to a nullable builtin JDBC type. If a variable length type then the size information will be set to the maximum possible. Collation type will be UCS_BASIC and derivation IMPLICIT. For well known types code may also use the pre-defined runtime types that are fields of this class, such as INTEGER.

Parameters

jdbcType:int

The int type of the JDBC type for which to get a corresponding SQL DataTypeDescriptor

Returns:DataTypeDescriptor

A new DataTypeDescriptor that corresponds to the Java type. A null return value means there is no corresponding SQL type

Get a descriptor that corresponds to a nullable builtin variable length JDBC type. Collation type will be UCS_BASIC and derivation IMPLICIT.

Parameters

jdbcType:int

The int type of the JDBC type for which to get a corresponding SQL DataTypeDescriptor

Returns:DataTypeDescriptor

A new DataTypeDescriptor that corresponds to the Java type. A null return value means there is no corresponding SQL type

Get a descriptor that corresponds to a builtin JDBC type. For well known types code may also use the pre-defined runtime types that are fields of this class, such as INTEGER. E.g. using DataTypeDescriptor.INTEGER is preferred to DataTypeDescriptor.getBuiltInDataTypeDescriptor(Types.INTEGER, true) (both will return the same immutable object).

Parameters

jdbcType:int

The int type of the JDBC type for which to get a corresponding SQL DataTypeDescriptor

isNullable:boolean

TRUE means it could contain NULL, FALSE means it definitely cannot contain NULL.

Returns:DataTypeDescriptor

A new DataTypeDescriptor that corresponds to the Java type. A null return value means there is no corresponding SQL type

Get a descriptor that corresponds to a builtin JDBC type. Collation type will be UCS_BASIC and derivation IMPLICIT.

Parameters

jdbcType:int

The int type of the JDBC type for which to get a corresponding SQL DataTypeDescriptor

isNullable:boolean

TRUE means it could contain NULL, FALSE means it definitely cannot contain NULL.

Returns:DataTypeDescriptor

A new DataTypeDescriptor that corresponds to the Java type. A null return value means there is no corresponding SQL type

Get a DataTypeServices that corresponds to a nullable builtin SQL type. Collation type will be UCS_BASIC and derivation IMPLICIT.

Parameters

sqlTypeName:String

The name of the type for which to get a corresponding SQL DataTypeDescriptor

Returns:DataTypeDescriptor

A new DataTypeDescriptor that corresponds to the Java type. A null return value means there is no corresponding SQL type (only for 'char')

Get a DataTypeServices that corresponds to a builtin SQL type Collation type will be UCS_BASIC and derivation IMPLICIT.

Parameters

sqlTypeName:String

The name of the type for which to get a corresponding SQL DataTypeDescriptor

Returns:DataTypeDescriptor

A new DataTypeDescriptor that corresponds to the Java type. A null return value means there is no corresponding SQL type (only for 'char')

Return a nullable catalog type for a JDBC builtin type and length.

Return a nullable catalog type for a fixed length JDBC builtin type.

Get a catlog type identical to the passed in type exception that the collationType is set to the passed in value.

Parameters

catalogType:TypeDescriptor

Type to be based upon.

collationType:int

Collation type of returned type.

Returns:TypeDescriptor

catalogType if it already has the correct collation, otherwise a new TypeDescriptor with the correct collation.

Get the simplified type descriptor that is intended to be stored in the system tables.

Return a type description identical to this type with the exception that its collation information is taken from the passed in information. If the type does not represent a string type then the collation will be unchanged and this is returned.

Returns:DataTypeDescriptor

This if collation would be unchanged otherwise a new type.

Get the collation derivation for this type. This applies only for character string types. For the other types, this api should be ignored. SQL spec talks about character string types having collation type and collation derivation associated with them (SQL spec Section 4.2.2 Comparison of character strings). If collation derivation says explicit or implicit, then it means that there is a valid collation type associated with the charcter string type. If the collation derivation is none, then it means that collation type can't be established for the character string type. 1)Collation derivation will be explicit if SQL COLLATE clause has been used for character string type (this is not a possibility for Derby 10.3 because we are not planning to support SQL COLLATE clause in the 10.3 release). 2)Collation derivation will be implicit if the collation can be determined w/o the COLLATE clause eg CREATE TABLE t1(c11 char(4)) then c11 will have collation of USER character set. Another eg, TRIM(c11) then the result character string of TRIM operation will have collation of the operand, c11. 3)Collation derivation will be none if the aggregate methods are dealing with character strings with different collations (Section 9.3 Data types of results of aggregations Syntax Rule 3aii). Collation derivation will be initialized to COLLATION_DERIVATION_IMPLICIT if not explicitly set.

Returns:int

Should be COLLATION_DERIVATION_NONE or COLLATION_DERIVATION_IMPLICIT

See Also

StringDataValue#COLLATION_DERIVATION_NONE, StringDataValue#COLLATION_DERIVATION_IMPLICIT, StringDataValue#COLLATION_DERIVATION_EXPLICIT

Gets the name of the collation type in this descriptor if the collation derivation is not NONE. If the collation derivation is NONE, then this method will return "NONE".

This method is used for generating error messages which will use correct string describing collation type/derivation.

Returns:String

the name of the collation being used in this type.

Gets the name of the specified collation type.

Parameters

collationType:int

The collation type.

Returns:String

The name, e g "TERRITORY_BASED:PRIMARY".

Obtain the collation type of the underlying catalog type. Shorthand method for getCatalogType().getCollationType().

See Also

TypeDescriptor#getCollationType()

Obtain the collation type from a collation property value.

Returns:int

The collation type, or -1 if not recognized.

Get the dominant type (DataTypeDescriptor) of the 2. For variable length types, the resulting type will have the biggest max length of the 2. If either side is nullable, then the result will also be nullable. If dealing with character string types, then make sure to set the collation info on the dominant type. Following algorithm will be used for dominant DTD's collation determination. Each of the steps of the algorithm have been numbered in the comments below and those same numbers are used in the actual algorithm below so it is easier to understand and maintain. Step 1 If the DTD for "this" node has the same collation derivation as the otherDTS, then check if their collation types match too. If the collation types match too, then DTD for dominant type will get the same collation derivation and type. Step 2 If the collation derivation for DTD for "this" node and otherDTS do not match, then check if one of them has the collation derivation of NONE. If that is the case, then dominant DTD will get the collation type and derivation of DTD whose collation derivation is not NONE. Step 3 If the collation derivation for DTD for "this" node and otherDTS do not match, and none of them have the derivation of NONE then it means that we are dealing with collation derivation of IMPLICIT and EXPLICIT and hence the dominant DTD should get collation derivation of NONE. This is not a possibility in Derby 10.3 because the only 2 possible collation derivation supported are IMPLICIT and NONE. Step 4 If the collation derivation for DTD for "this" node and otherDTS match, then check if the collation types match too. If not, then the dominant DTD should get collation derivation of NONE.

Parameters

otherDTS:DataTypeDescriptor

DataTypeDescriptor to compare with.

cf:ClassFactory

A ClassFactory

Returns:DataTypeDescriptor

DataTypeDescriptor DTS for dominant type

Return the SQL type name and, if applicable, scale/precision/length for this DataTypeDescriptor. Note that we want the values from *this* object specifically, not the max values defined on this.typeId.

Get the jdbc type id for this type. JDBC type can be found in java.sql.Types. Shorthand method for getCatalogType().getJDBCTypeId().

Returns:int

a jdbc type, e.g. java.sql.Types.DECIMAL

See Also

Types

Shorthand method for getCatalogType().getMaximumWidth().

See Also

TypeDescriptor#getMaximumWidth

Get a Null for this type.

Return a type descriptor identical to the this type with the exception of its nullability. If the nullablity required matches the nullability of this then this is returned.

Parameters

isNullable:boolean

True to return a nullable type, false otherwise.

Get the maximum and minimum value for a fixed numeric type. Throws an unimplemented feature exception for a non-numeric type.

Returns the number of decimal digits for the datatype, if applicable. Shorthand method for getCatalogType().getPrecision().

Returns:int

The number of decimal digits for the datatype. Returns zero for non-numeric datatypes.

See Also

TypeDescriptor#getPrecision()

Get a catalog type that corresponds to a SQL Row Multiset

Parameters

columnNames:String[]

Names of the columns in the Row Muliset

catalogTypes:TypeDescriptor[]

Types of the columns in the Row Muliset

Returns:TypeDescriptor

A new DataTypeDescriptor describing the SQL Row Multiset

Returns the number of digits to the right of the decimal for the datatype, if applicable. Shorthand method for getCatalogType().getScale().

Returns:int

The number of digits to the right of the decimal for the datatype. Returns zero for non-numeric datatypes.

See Also

TypeDescriptor#getScale()

Get a DataTypeServices that corresponds to a Java type

Parameters

javaTypeName:String

The name of the Java type for which to get a corresponding SQL DataTypeDescriptor

Returns:DataTypeDescriptor

A new DataTypeDescriptor that corresponds to the Java type. A null return value means there is no corresponding SQL type (only for 'char')

Get a DataTypeServices that corresponds to a Java type

Parameters

javaTypeName:String

The name of the Java type for which to get a corresponding SQL DataTypeDescriptor

isNullable:boolean

TRUE means it could contain NULL, FALSE means it definitely cannot contain NULL.

Returns:DataTypeDescriptor

A new DataTypeDescriptor that corresponds to the Java type. A null return value means there is no corresponding SQL type (only for 'char')

Get a DataTypeDescriptor that corresponds to a Java type

Parameters

javaTypeName:String

The name of the Java type for which to get a corresponding SQL DataTypeDescriptor

precision:int

The number of decimal digits

scale:int

The number of digits after the decimal point

isNullable:boolean

TRUE means it could contain NULL, FALSE means it definitely cannot contain NULL.

maximumWidth:int

The maximum width of a data value represented by this type.

Returns:DataTypeDescriptor

A new DataTypeDescriptor that corresponds to the Java type. A null return value means there is no corresponding SQL type.

Converts this data type descriptor (including length/precision) to a string. E.g. VARCHAR(30) or java.util.Hashtable

Returns:String

String version of datatype, suitable for running through the Parser.

Return a runtime type for a catalog type.

Implements org.apache.derby.iapi.services.io.TypedFormat.getTypeFormatId.

Get the formatID which corresponds to this class.

Returns:int

the formatID of this class

Gets the TypeId for the datatype.

Returns:TypeId

The TypeId for the datatype.

Gets the name of this datatype.

Returns:String

the name of this datatype

Determine if an ASCII stream can be inserted into a column or parameter of type jdbcType.

Parameters

jdbcType:int

JDBC type of column or parameter

Returns:boolean

true if an ASCII stream can be inserted; false otherwise

Determine if a binary stream can be inserted into a column or parameter of type jdbcType.

Parameters

jdbcType:int

JDBC type of column or parameter

Returns:boolean

true if a binary stream can be inserted; false otherwise

Determine if a character stream can be inserted into a column or parameter of type jdbcType.

Parameters

jdbcType:int

JDBC type of column or parameter

Returns:boolean

true if a character stream can be inserted; false otherwise

Check whether or not the 2 types (DataTypeDescriptor) have the same type and length. This is useful for UNION when trying to decide whether a NormalizeResultSet is required.

Parameters

otherDTS:DataTypeDescriptor

DataTypeDescriptor to compare with.

Returns:boolean

boolean Whether or not the 2 DTSs have the same type and length.

Compare JdbcTypeIds to determine if they represent equivalent SQL types. For example Types.NUMERIC and Types.DECIMAL are equivalent

Parameters

existingType:int

JDBC type id of Derby data type

jdbcTypeId:int

JDBC type id passed in from application.

Returns:boolean

boolean true if types are equivalent, false if not

Returns TRUE if the datatype can contain NULL, FALSE if not. JDBC supports a return value meaning "nullability unknown" - I assume we will never have columns where the nullability is unknown. Shorthand method for getCatalogType().isNullable();

Returns:boolean

TRUE if the datatype can contain NULL, FALSE if not.

Check to make sure that this type id is something a user can create him/herself directly through an SQL CREATE TABLE statement. This method is used for CREATE TABLE AS ... WITH [NO] DATA binding because it's possible for the query to return types which are not actually creatable for a user. DERBY-2605. Three examples are: JAVA_OBJECT: A user can select columns of various java object types from system tables, but s/he is not allowed to create such a column him/herself. DECIMAL: A user can specify a VALUES clause with a constant that has a precision of greater than 31. Derby can apparently handle such a value internally, but the user is not supposed to be able create such a column him/herself.

Returns:boolean

True if the type associated with this DTD can be created via the CREATE TABLE syntax; false otherwise.

Implements java.io.Externalizable.readExternal.

Read this object from a stream of stored objects.

Parameters

in:ObjectInput

read this.

Exceptions

IOException:

thrown on error

ClassNotFoundException:

thrown on error

Overrides java.lang.Object.toString.

Doc from java.lang.Object.toString.

Returns a string representation of the object. Satisfying this method's contract implies a non-null result must be returned.

Returns:String

a string representation of the object

Implements java.io.Externalizable.writeExternal.

Write this object to a stream of stored objects.

Parameters

out:ObjectOutput

write bytes here.

Exceptions

IOException:

thrown on error