org.fastnate.generator.dialect

Class GeneratorDialect

java.lang.Object

org.fastnate.generator.dialect.GeneratorDialect

Direct Known Subclasses:

H2Dialect, MsSqlDialect, MySqlDialect, OracleDialect, PostgresDialect

public abstract class GeneratorDialect
extends Object

Handles database specific conversions. The conversions are limited, for some of the known limitations, see the database specific implementations.

Author:

Tobias Liefke

See Also:

Comparison of different SQL implementations

Field Summary

Fields

Modifier and Type	Field and Description
static Date	NOW Represents the constant for writing the "now" function to SQL.

Constructor Summary

Constructors

Constructor and Description
GeneratorDialect()

Method Summary

Modifier and Type	Method and Description
protected void	addQuotedCharacter(StringBuilder result, char c) Adds a quoted character to the result string buffer.
List<? extends EntityStatement>	adjustNextIdentityValue(String tableName, String columnName, long nextValue) Adjusts the next value of the given identity column to ensure that it is bigger than the last generated value.
List<? extends EntityStatement>	adjustNextSequenceValue(String sequenceName, long currentSequenceValue, long nextSequenceValue, int incrementSize) Adjusts the given sequence to ensure that the next value is exactly the given value.
String	buildCurrentSequenceValue(String sequence, int incrementSize) Builds the SQL expression that is used for referencing the current value of the given sequence.
String	buildNextSequenceValue(String sequence, int incrementSize) Builds the SQL expression resp. statement that is used for creating the next value of the given sequence.
String	convertBooleanValue(boolean value) Converts a boolean value for the current database type.
String	convertTemporalValue(Date value, javax.persistence.TemporalType type) Converts a date to an appropriate SQL expression.
String	createBlobExpression(byte[] blob) Converts the given byte array to an SQL expression for the current database.
protected String	createHexBlobExpression(String prefix, byte[] blob, String suffix) Creates the hex presentation of the given blob.
String	createSql(EntityStatement stmt) Creates an SQL statement from the given insert statement.
javax.persistence.GenerationType	getAutoGenerationType() Resolves the GenerationType used, if GenerationType.AUTO is set for a GeneratedValue.
String	getOptionalTable() Returns the string to use when no table is required, e.g. for "SELECT 1, 2 FROM DUAL" this would return "FROM DUAL".
boolean	isEmptyStringEqualToNull() Indicates that the empty string is equal to null in this database.
boolean	isIdentitySupported() Indicates that identity columns are supported by the database.
boolean	isNextSequenceValueInInsertSupported() Indicates that a sequence may be updated in the insert statement.
boolean	isSequenceInWhereSupported() Indicates that references to sequences in WHERE expressions are supported.
boolean	isSequenceSupported() Indicates that sequences are supported by the database.
String	quoteString(String value) Quotes the given string.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NOW

public static final Date NOW

Represents the constant for writing the "now" function to SQL.

Constructor Detail

GeneratorDialect

public GeneratorDialect()

Method Detail

addQuotedCharacter

protected void addQuotedCharacter(StringBuilder result,
                                  char c)

Adds a quoted character to the result string buffer.

Parameters:

result - the current result buffer

c - the character to quote

adjustNextIdentityValue

public List<? extends EntityStatement> adjustNextIdentityValue(String tableName,
                                                               String columnName,
                                                               long nextValue)

Adjusts the next value of the given identity column to ensure that it is bigger than the last generated value.

Parameters:

tableName - the name of the table of the column

columnName - the name of the (auto increment) identity column

nextValue - the next value of the identity column

Returns:

all statements that are necessary to adjust the next value

adjustNextSequenceValue

public List<? extends EntityStatement> adjustNextSequenceValue(String sequenceName,
                                                               long currentSequenceValue,
                                                               long nextSequenceValue,
                                                               int incrementSize)

Adjusts the given sequence to ensure that the next value is exactly the given value.

Parameters:

sequenceName - the name of the sequence

currentSequenceValue - the current value of the sequence

nextSequenceValue - the next value of the sequence

incrementSize - the increment size of the sequence

Returns:

all statements necessary to adjust the sequence

buildCurrentSequenceValue

public String buildCurrentSequenceValue(String sequence,
                                        int incrementSize)

Builds the SQL expression that is used for referencing the current value of the given sequence.

Parameters:

sequence - the name of the sequence

incrementSize - the expected incrementSize, as given in the schema - used by some dialects to ensure that exactly that inrement is used

Returns:

the SQL expression to use in statement

buildNextSequenceValue

public String buildNextSequenceValue(String sequence,
                                     int incrementSize)

Builds the SQL expression resp. statement that is used for creating the next value of the given sequence. Depending on isNextSequenceValueInInsertSupported() this will return an expression or a statement.

Parameters:

sequence - the name of the sequence

incrementSize - the expected incrementSize, as given in the schema - used by some dialects to ensure that exactly that inrement is used

Returns:

the SQL to use in resp. before the insert / update statement

convertBooleanValue

public String convertBooleanValue(boolean value)

Converts a boolean value for the current database type.

Parameters:

value - the value to convert

Returns:

the string representation of the value

convertTemporalValue

public String convertTemporalValue(Date value,
                                   javax.persistence.TemporalType type)

Converts a date to an appropriate SQL expression.

Parameters:

value - the timestamp value

type - the type

Returns:

SQL expression representing the value.

createBlobExpression

public String createBlobExpression(byte[] blob)

Converts the given byte array to an SQL expression for the current database.

Parameters:

blob - the bytes to convert

Returns:

the expression for the bytes

createHexBlobExpression

protected String createHexBlobExpression(String prefix,
                                         byte[] blob,
                                         String suffix)

Creates the hex presentation of the given blob.

Parameters:

prefix - the prefix to add to the hex

blob - the binary blob to convert

suffix - the suffix to add to the hex

Returns:

prefix + hex(blob) + suffix

createSql

public String createSql(EntityStatement stmt)

Creates an SQL statement from the given insert statement. Usually just EntityStatement.toString() is returned, but some dialects could change database specific things.

Parameters:

stmt - contains the table and all column values

Returns:

the SQL

getAutoGenerationType

public javax.persistence.GenerationType getAutoGenerationType()

Resolves the GenerationType used, if GenerationType.AUTO is set for a GeneratedValue.

Returns:

the replacement for GenerationType.AUTO for the current dialect in Hibernate.

getOptionalTable

public String getOptionalTable()

Returns the string to use when no table is required, e.g. for "SELECT 1, 2 FROM DUAL" this would return "FROM DUAL".

Returns:

the SQL to use in "SELECT x [OPTIONALTABLE] WHERE ..."

isEmptyStringEqualToNull

public boolean isEmptyStringEqualToNull()

Indicates that the empty string is equal to null in this database. Important for NotNull constraints, where an empty string would result in the same constraint violation.

Returns:

true if this database assumes that an empty string is the same as null

isIdentitySupported

public boolean isIdentitySupported()

Indicates that identity columns are supported by the database.

Returns:

true if the database supports identities

isNextSequenceValueInInsertSupported

public boolean isNextSequenceValueInInsertSupported()

Indicates that a sequence may be updated in the insert statement.

Returns:

true to indicate that buildNextSequenceValue(String,int) will return an expression that may be used in an INSERT statement, false to indicate that buildNextSequenceValue(String,int) returns a full statement

isSequenceInWhereSupported

public boolean isSequenceInWhereSupported()

Indicates that references to sequences in WHERE expressions are supported.

Returns:

true if this database supports sequences in WHERE expressions

isSequenceSupported

public boolean isSequenceSupported()

Indicates that sequences are supported by the database.

Returns:

true if the database supports sequences

quoteString

public String quoteString(String value)

Quotes the given string.

Parameters:

value - the value to quote

Returns:

the quoted string