liquibase.sqlgenerator
Interface SqlGenerator<StatementType extends SqlStatement>

Type Parameters:

StatementType - Used to specify which type of SqlStatement this generator supports. If it supports multiple SqlStatement types, pass SqlStatement. The SqlGeneratorFactory will use this paramter to augment the response from the supports() method

All Superinterfaces:

PrioritizedService

All Known Implementing Classes:

AbstractSqlGenerator, AddAutoIncrementGenerator, AddAutoIncrementGeneratorDB2, AddAutoIncrementGeneratorHsqlH2, AddAutoIncrementGeneratorInformix, AddAutoIncrementGeneratorMySQL, AddAutoIncrementGeneratorSQLite, AddColumnGenerator, AddColumnGeneratorDefaultClauseBeforeNotNull, AddColumnGeneratorSQLite, AddDefaultValueGenerator, AddDefaultValueGeneratorDerby, AddDefaultValueGeneratorInformix, AddDefaultValueGeneratorMaxDB, AddDefaultValueGeneratorMSSQL, AddDefaultValueGeneratorMySQL, AddDefaultValueGeneratorOracle, AddDefaultValueGeneratorPostgres, AddDefaultValueGeneratorSybase, AddDefaultValueGeneratorSybaseASA, AddDefaultValueSQLite, AddForeignKeyConstraintGenerator, AddPrimaryKeyGenerator, AddPrimaryKeyGeneratorInformix, AddUniqueConstraintGenerator, AddUniqueConstraintGeneratorInformix, AddUniqueConstraintGeneratorTDS, AlterSequenceGenerator, ClearDatabaseChangeLogTableGenerator, CommentGenerator, CopyRowsGenerator, CreateDatabaseChangeLogLockTableGenerator, CreateDatabaseChangeLogTableGenerator, CreateDatabaseChangeLogTableGeneratorFirebird, CreateDatabaseChangeLogTableGeneratorSybase, CreateIndexGenerator, CreateIndexGeneratorPostgres, CreateSequenceGenerator, CreateTableGenerator, CreateTableGeneratorInformix, CreateViewGenerator, CreateViewGeneratorInformix, DeleteGenerator, DropColumnGenerator, DropDefaultValueGenerator, DropForeignKeyConstraintGenerator, DropIndexGenerator, DropPrimaryKeyGenerator, DropSequenceGenerator, DropTableGenerator, DropUniqueConstraintGenerator, DropViewGenerator, FindForeignKeyConstraintsGeneratorDB2, FindForeignKeyConstraintsGeneratorHsql, FindForeignKeyConstraintsGeneratorMSSQL, FindForeignKeyConstraintsGeneratorMySQL, FindForeignKeyConstraintsGeneratorOracle, FindForeignKeyConstraintsGeneratorPostgres, GetNextChangeSetSequenceValueGenerator, GetViewDefinitionGenerator, GetViewDefinitionGeneratorDB2, GetViewDefinitionGeneratorDerby, GetViewDefinitionGeneratorFirebird, GetViewDefinitionGeneratorHsql, GetViewDefinitionGeneratorInformix, GetViewDefinitionGeneratorMaxDB, GetViewDefinitionGeneratorMSSQL, GetViewDefinitionGeneratorOracle, GetViewDefinitionGeneratorPostgres, GetViewDefinitionGeneratorSybase, GetViewDefinitionGeneratorSybaseASA, InitializeDatabaseChangeLogLockTableGenerator, InsertDataChangeGenerator, InsertGenerator, InsertOrUpdateGenerator, InsertOrUpdateGeneratorDB2, InsertOrUpdateGeneratorH2, InsertOrUpdateGeneratorHsql, InsertOrUpdateGeneratorMSSQL, InsertOrUpdateGeneratorMySQL, InsertOrUpdateGeneratorOracle, InsertOrUpdateGeneratorPostgres, LockDatabaseChangeLogGenerator, MarkChangeSetRanGenerator, ModifyDataTypeGenerator, RawSqlGenerator, ReindexGeneratorSQLite, RemoveChangeSetRanStatusGenerator, RenameColumnGenerator, RenameTableGenerator, RenameViewGenerator, ReorganizeTableGeneratorDB2, RuntimeGenerator, SelectFromDatabaseChangeLogGenerator, SelectFromDatabaseChangeLogLockGenerator, SetColumnRemarksGenerator, SetNullableGenerator, SetTableRemarksGenerator, StoredProcedureGenerator, TagDatabaseGenerator, UnlockDatabaseChangeLogGenerator, UpdateChangeSetChecksumGenerator, UpdateDataChangeGenerator, UpdateGenerator

public interface SqlGenerator<StatementType extends SqlStatement>
extends PrioritizedService

SqlGenerator implementations take a database-independent SqlStatement interface and create a database-specific Sql object. SqlGenerators are registered with the SqlGeneratorFactory, which is used to determine the correct generator to use for a given statment/database combination.

The SqlGenerator implementations are responsible for determining whether the data contained in the SqlStatement method is valid using the validate method.

Naming Conventions:
Default SqlGenerators for a particular SqlStatement use the same name as the SqlStatement class, replacing "Statement" with "Generator" (e.g.: CreateTableStatement -> CreateTableGenerator). Database-specific or alternate SqlGenerators append a descrition of what makes them different appended (e.g. CreateTableStatement -> CreateTableGeneratorOracle)

NOTE: There is only one instance of each SqlGenerator implementation created, and they must be thread safe.

Lifecycle:

1. Instance of SqlGenerator subclass is created when registered with SqlGeneratorFactory
2. For each SqlStatement to execute, SqlGeneratorFactory calls supports() to determine if the given SqlGenerator will work for the current SqlStatement/Database combination
3. SqlGeneratorFactory calls getPriority to determine which of all the SqlGenerators that support a given SqlStatement/Database combination is the best to use.
4. Liquibase calls validate() on the best SqlGenerator to determine if the data contained in the SqlStatement is correct and complete for the given Database
5. If validate returns a no-error ValidationErrors object, Liquibase will call the generateSql() method and execute the resuling SQL against the database.

See Also:

SqlGeneratorFactory, SqlStatement, Sql

Field Summary

static int	PRIORITY_DATABASE
static int	PRIORITY_DEFAULT

Method Summary

boolean	generateRollbackStatementsIsVolatile(Database database)
Sql[]	generateSql(StatementType statement, Database database, SqlGeneratorChain sqlGeneratorChain) Generate the actual Sql for the given statement and database.
boolean	generateStatementsIsVolatile(Database database) Does this change require access to the database metadata? If true, the change cannot be used in an updateSql-style command.
int	getPriority() Of all the SqlGenerators that "support" a given SqlStatement/Database, SqlGeneratorFactory will return the one with the highest priority.
boolean	supports(StatementType statement, Database database) Does this generator support the given statement/database combination? Do not validate the statement with this method, only return if it can suppot it.
ValidationErrors	validate(StatementType statement, Database database, SqlGeneratorChain sqlGeneratorChain) Validate the data contained in the SqlStatement.
Warnings	warn(StatementType statementType, Database database, SqlGeneratorChain sqlGeneratorChain)

Field Detail

PRIORITY_DEFAULT

static final int PRIORITY_DEFAULT

See Also:

Constant Field Values

PRIORITY_DATABASE

static final int PRIORITY_DATABASE

See Also:

Constant Field Values

Method Detail

getPriority

int getPriority()

Of all the SqlGenerators that "support" a given SqlStatement/Database, SqlGeneratorFactory will return the one with the highest priority.

Specified by:

getPriority in interface PrioritizedService

Returns:

supports

boolean supports(StatementType statement,
                 Database database)

Does this generator support the given statement/database combination? Do not validate the statement with this method, only return if it can suppot it.

generateStatementsIsVolatile

boolean generateStatementsIsVolatile(Database database)

Does this change require access to the database metadata? If true, the change cannot be used in an updateSql-style command.

generateRollbackStatementsIsVolatile

boolean generateRollbackStatementsIsVolatile(Database database)

validate

ValidationErrors validate(StatementType statement,
                          Database database,
                          SqlGeneratorChain sqlGeneratorChain)

Validate the data contained in the SqlStatement. If there are no errors, return an empty ValidationErrors object, not a null value. Liquibase will inspect the ValidationErrors result before attempting to call generateSql.

warn

Warnings warn(StatementType statementType,
              Database database,
              SqlGeneratorChain sqlGeneratorChain)

generateSql

Sql[] generateSql(StatementType statement,
                  Database database,
                  SqlGeneratorChain sqlGeneratorChain)

Generate the actual Sql for the given statement and database.