package liquibase.sqlgenerator.core;

 import liquibase.database.Database;

 import liquibase.database.core.OracleDatabase;

 import liquibase.exception.ValidationErrors;

 import liquibase.sql.Sql;

 import liquibase.sql.UnparsedSql;

 import liquibase.sqlgenerator.SqlGenerator;

 import liquibase.sqlgenerator.SqlGeneratorChain;

 import liquibase.statement.core.SelectFromDatabaseChangeLogLockStatement;

 import liquibase.util.StringUtils;

 public class SelectFromDatabaseChangeLogLockGenerator extends

         AbstractSqlGenerator<SelectFromDatabaseChangeLogLockStatement> {

     public ValidationErrors validate(SelectFromDatabaseChangeLogLockStatement statement, Database database,

             SqlGeneratorChain sqlGeneratorChain) {

         ValidationErrors errors = new ValidationErrors();

         errors.checkRequiredField("columnToSelect", statement.getColumnsToSelect());

         return errors;

     }

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

             SqlGeneratorChain sqlGeneratorChain) {

         String liquibaseSchema;

         liquibaseSchema = database.getLiquibaseSchemaName();

         String[] columns = statement.getColumnsToSelect();

         int numberOfColumns = columns.length;

         String[] escapedColumns = new String[numberOfColumns];

         for (int i = 0; i < numberOfColumns; i++) {

             escapedColumns[i] = database.escapeColumnName(liquibaseSchema,

                     database.getDatabaseChangeLogLockTableName(), columns[i]);

         }

         String sql = "SELECT " + StringUtils.join(escapedColumns, ",") + " FROM "

                 + database.escapeTableName(liquibaseSchema, database.getDatabaseChangeLogLockTableName()) + " WHERE "

                 + database.escapeColumnName(liquibaseSchema, database.getDatabaseChangeLogLockTableName(), "ID") + "=1";

         if (database instanceof OracleDatabase) {

             sql += " FOR UPDATE";

         }

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

     }

 }