package liquibase.sqlgenerator.core;

 import liquibase.database.Database;

 import liquibase.database.core.MaxDBDatabase;

 import liquibase.database.core.MySQLDatabase;

 import liquibase.database.core.OracleDatabase;

 import liquibase.database.core.SQLiteDatabase;

 import liquibase.database.core.SybaseASADatabase;

 import liquibase.exception.ValidationErrors;

 import liquibase.sql.Sql;

 import liquibase.sql.UnparsedSql;

 import liquibase.sqlgenerator.SqlGeneratorChain;

 import liquibase.statement.core.DropUniqueConstraintStatement;

 public class DropUniqueConstraintGenerator extends AbstractSqlGenerator<DropUniqueConstraintStatement> {

     @Override

     public boolean supports(DropUniqueConstraintStatement statement, Database database) {

         return !(database instanceof SQLiteDatabase);

     }

     @Override

     public ValidationErrors validate(DropUniqueConstraintStatement dropUniqueConstraintStatement, Database database,

             SqlGeneratorChain sqlGeneratorChain) {

         ValidationErrors validationErrors = new ValidationErrors();

         validationErrors.checkRequiredField("tableName", dropUniqueConstraintStatement.getTableName());

         return validationErrors;

     }

     @Override

     public Sql[] generateSql(DropUniqueConstraintStatement statement, Database database,

             SqlGeneratorChain sqlGeneratorChain) {

         String sql;

         if (database instanceof MySQLDatabase) {

             sql = "ALTER TABLE " + database.escapeTableName(statement.getSchemaName(), statement.getTableName())

                     + " DROP KEY " + database.escapeConstraintName(statement.getConstraintName());

         } else if (database instanceof MaxDBDatabase) {

             sql = "DROP INDEX " + database.escapeConstraintName(statement.getConstraintName()) + " ON "

                     + database.escapeTableName(statement.getSchemaName(), statement.getTableName());

         } else if (database instanceof OracleDatabase) {

             sql = "ALTER TABLE " + database.escapeTableName(statement.getSchemaName(), statement.getTableName())

                     + " DROP CONSTRAINT " + database.escapeConstraintName(statement.getConstraintName())

                     + " DROP INDEX";

         } else if (database instanceof SybaseASADatabase) {

             sql = "ALTER TABLE " + database.escapeTableName(statement.getSchemaName(), statement.getTableName())

                     + " DROP UNIQUE (" + statement.getUniqueColumns() + ")";

         } else {

             sql = "ALTER TABLE " + database.escapeTableName(statement.getSchemaName(), statement.getTableName())

                     + " DROP CONSTRAINT " + database.escapeConstraintName(statement.getConstraintName());

         }

         return new Sql[] { new UnparsedSql(sql) };

     }

 }