net.sf.basedb.core.dbengine
Class AbstractDbEngine

java.lang.Object
  net.sf.basedb.core.dbengine.AbstractDbEngine

All Implemented Interfaces:

DbEngine

Direct Known Subclasses:

DefaultDbEngine, MySQLEngine, PostgresDbEngine

public abstract class AbstractDbEngine
extends Object
implements DbEngine

An abstract superclass with default implementations for most DbEngine methods. Subclasses only needs to override methods which behave differently.

Version:

2.0

Author:

nicklas

Last modified

$Date: 2011-11-22 11:47:22 +0100 (Tue, 22 Nov 2011) $

Field Summary

private static Pattern

valid A regexp checking for invalid characters.

Constructor Summary

AbstractDbEngine()
Create AbstractDbEngine.

Method Summary

String	abs(String value) Return ABS(<value>).
String	castToDate(String value) Get a function that casts a date/timestamp to a date (eg. no time should be included in the result).
boolean	checkForInvalidNumberOperation() Returns FALSE.
String	exp(String value) Return EXP(<value>).
String	getApproximateRowCountSql(String catalog, String schema, String table) Get an SQL statement that returns an approximate count for the number of rows in the given table.
String	getCaseSensitiveVarchar(int length) Return null.
String	getQuotedName(String name) Put quotes (") around the name.
String	inspectSchemaGenerationSQL(String sql, Dialect dialect, SchemaGenerator.Mode mode) Remove "not null" constraints from "alter table ... add column" statements that doesn't supply a default value for the new column when updating.
boolean	isValidColumnName(String columnName) Checks that the name only contains the following characters: a-zA-Z0-9_ It must also start with a letter or underscore.
protected boolean	isValidName(String name) Check that the name only contains a-zA-Z0-9_ and starts with a letter or underscore.
boolean	isValidTableName(String tableName) Checks that the name only contains the following characters: a-zA-Z0-9_ It must also start with a letter or underscore.
String	ln(String value) Return LN(<value>).
String	makeSafeCreateTable(String sql, String catalog, String schema, String table) Return the SQL unmodified.
String	power(String base, String exponent) Return POWER(<base>, <exponent>).
String	rlike(String value, String regexp) Return <value> = <regexp>
boolean	selectOrderByColumnsIfDistinct() Returns FALSE.
boolean	supportColumnAliasInGroupBy() Returns FALSE.
boolean	supportColumnAliasInHaving() Returns FALSE.
boolean	supportColumnAliasInOrderBy() Returns FALSE.
boolean	supportsColumnAliasInWhere() Returns FALSE.
boolean	useSavePointToContinueTransactionFromSqlFailure() If the underlying database need to create a savepoint before executing an SQL statement that results in an error in order to be able to continue using the same transaction for other SQL queries.
boolean	useThetaJoin() Most databases doesn't.

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.sf.basedb.core.dbengine.DbEngine

analyzeAfterBatchOperation, caseInsensitiveComparison, getAnalyzeTableSql, getCreateForeignKeySql, getCreateIndexSql, getCreatePrimaryKeySql, getDropForeignKeySql, getDropIndexSql, getDropPrimaryKey, getInsertAutoIncrementSql, getOptimizeTableSql

Field Detail

valid

private static final Pattern valid

A regexp checking for invalid characters.

Constructor Detail

AbstractDbEngine

public AbstractDbEngine()

Create AbstractDbEngine.

Method Detail

makeSafeCreateTable

public String makeSafeCreateTable(String sql,
                                  String catalog,
                                  String schema,
                                  String table)

Return the SQL unmodified.

Specified by:

makeSafeCreateTable in interface DbEngine

Parameters:

sql - The original SQL

catalog - The name of the catalog (database) where the table is being create, or null if it is located in the current catalog

schema - The name of the schema where the table is being created, or null if is located in the current schema

table - The name of the table that is being created

Returns:

The modified or unmodified SQL statement

Since:

2.6

useThetaJoin

public boolean useThetaJoin()

Most databases doesn't. Any more than Oracle?

Specified by:

useThetaJoin in interface DbEngine

Returns:

TRUE for theta join, FALSE for ansi join

supportsColumnAliasInWhere

public boolean supportsColumnAliasInWhere()

Returns FALSE. It should always work.

Specified by:

supportsColumnAliasInWhere in interface DbEngine

Returns:

TRUE if column aliases are supported, FALSE otherwise

supportColumnAliasInOrderBy

public boolean supportColumnAliasInOrderBy()

Returns FALSE. It should always work.

Specified by:

supportColumnAliasInOrderBy in interface DbEngine

Returns:

TRUE if column aliases are supported, FALSE otherwise

supportColumnAliasInGroupBy

public boolean supportColumnAliasInGroupBy()

Returns FALSE. It should always work.

Specified by:

supportColumnAliasInGroupBy in interface DbEngine

Returns:

TRUE if column aliases are supported, FALSE otherwise

supportColumnAliasInHaving

public boolean supportColumnAliasInHaving()

Returns FALSE. It should always work.

Specified by:

supportColumnAliasInHaving in interface DbEngine

Returns:

TRUE if column aliases are supported, FALSE otherwise

checkForInvalidNumberOperation

public boolean checkForInvalidNumberOperation()

Returns FALSE.

Specified by:

checkForInvalidNumberOperation in interface DbEngine

Returns:

TRUE if we need to check the numbers, FALSE otherwise

selectOrderByColumnsIfDistinct

public boolean selectOrderByColumnsIfDistinct()

Returns FALSE.

Specified by:

selectOrderByColumnsIfDistinct in interface DbEngine

Returns:

TRUE if order by columns must be selected, FALSE otherwise

ln

public String ln(String value)

Return LN(<value>).

Specified by:

ln in interface DbEngine

Parameters:

value - The value to take the logarithm of

Returns:

The function call that calculates the logartihm

abs

public String abs(String value)

Return ABS(<value>).

Specified by:

abs in interface DbEngine

Parameters:

value - The value to use in the calculation

Returns:

The function call that calculates the absolute value

exp

public String exp(String value)

Return EXP(<value>).

Specified by:

exp in interface DbEngine

Parameters:

value - The value to use in the calculation

Returns:

The function call that calculates the exponential

power

public String power(String base,
                    String exponent)

Return POWER(<base>, <exponent>).

Specified by:

power in interface DbEngine

Parameters:

base - The base in the expression

exponent - The exponent in the expression

Returns:

The function call that calculates the power

rlike

public String rlike(String value,
                    String regexp)

Return <value> = <regexp>

Specified by:

rlike in interface DbEngine

Parameters:

value - The left value

regexp - The regular expression as a string

Returns:

The function call/expression that matches the value agains the regular expression

Since:

2.8

isValidTableName

public boolean isValidTableName(String tableName)

Checks that the name only contains the following characters: a-zA-Z0-9_ It must also start with a letter or underscore.

Specified by:

isValidTableName in interface DbEngine

Parameters:

tableName - The string to check

Returns:

TRUE if the name is valid, FALSE if not

Since:

2.4

isValidColumnName

public boolean isValidColumnName(String columnName)

Checks that the name only contains the following characters: a-zA-Z0-9_ It must also start with a letter or underscore.

Specified by:

isValidColumnName in interface DbEngine

Parameters:

columnName - The string to check

Returns:

TRUE if the name is valid, FALSE if not

getCaseSensitiveVarchar

public String getCaseSensitiveVarchar(int length)

Return null.

Specified by:

getCaseSensitiveVarchar in interface DbEngine

Parameters:

length - The maximum length that needs to be stored in the column

Returns:

The SQL snippet that creates the column, or null to let Hibernate use the default SQL

Since:

2.9

castToDate

public String castToDate(String value)

Description copied from interface: DbEngine

Get a function that casts a date/timestamp to a date (eg. no time should be included in the result).

Specified by:

castToDate in interface DbEngine

Parameters:

value - The value to cast

Returns:

ANSI SQL: cast(value as date)

inspectSchemaGenerationSQL

public String inspectSchemaGenerationSQL(String sql,
                                         Dialect dialect,
                                         SchemaGenerator.Mode mode)

Remove "not null" constraints from "alter table ... add column" statements that doesn't supply a default value for the new column when updating.

Specified by:

inspectSchemaGenerationSQL in interface DbEngine

Parameters:

sql - The original SQL statment as generated by Hibernate

dialect - The Hibernate dialect currently in use

mode - The installation mode

Returns:

The SQL statement which may have been modified or null to skip executing the statment

Since:

3.1

getQuotedName

public String getQuotedName(String name)

Put quotes (") around the name.

Specified by:

getQuotedName in interface DbEngine

Parameters:

name - The name of an object in the database

Returns:

A quoted name

useSavePointToContinueTransactionFromSqlFailure

public boolean useSavePointToContinueTransactionFromSqlFailure()

Description copied from interface: DbEngine

If the underlying database need to create a savepoint before executing an SQL statement that results in an error in order to be able to continue using the same transaction for other SQL queries. This is, for example, needed by PostgreSQL which will otherwise ignore all SQL statements executed after the one that caused an error.

Specified by:

useSavePointToContinueTransactionFromSqlFailure in interface DbEngine

Returns:

Always FALSE, but may be overridden by subclasses

getApproximateRowCountSql

public String getApproximateRowCountSql(String catalog,
                                        String schema,
                                        String table)

Description copied from interface: DbEngine

Get an SQL statement that returns an approximate count for the number of rows in the given table. The SQL query should return a single row with a single value.

Specified by:

getApproximateRowCountSql in interface DbEngine

Parameters:

catalog - The name of the catalog (database) where the table is located, or null if it is located in the current catalog

schema - The name of the schema where the table is located, or null if is located in the current schema

table - The name of the table

Returns:

null, since this depends on capabilities of underlying database

isValidName

protected boolean isValidName(String name)

Check that the name only contains a-zA-Z0-9_ and starts with a letter or underscore.

Since:

2.4