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/*
* Copyright 2004-2011 H2 Group.
* Copyright 2011 James Moger.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.iciql;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.SQLException;
import com.iciql.TableDefinition.IndexDefinition;
import com.iciql.util.StatementBuilder;
import com.iciql.util.StringUtils;
/**
* This interface defines points where iciql can build different statements
* depending on the database used.
*/
public interface SQLDialect {
/**
* Configure the dialect from the database connection.
*
* @param conn
*/
void configureDialect(Connection conn);
/**
* Returns a properly formatted table name for the dialect.
*
* @param schema
* the schema name, or null for no schema
* @param table
* the properly formatted table name
* @return the SQL snippet
*/
String prepareTableName(String schema, String table);
/**
* Returns a properly formatted column name for the dialect.
*
* @param name
* the column name
* @return the properly formatted column name
*/
String prepareColumnName(String name);
/**
* Get the CREATE INDEX statement.
*
* @param schema
* the schema name
* @param table
* the table name
* @param index
* the index definition
* @return the SQL statement
*/
String prepareCreateIndex(String schema, String table, IndexDefinition index);
/**
* Append "LIMIT limit" to the SQL statement.
*
* @param stat
* the statement
* @param limit
* the limit
*/
void appendLimit(SQLStatement stat, long limit);
/**
* Append "OFFSET offset" to the SQL statement.
*
* @param stat
* the statement
* @param offset
* the offset
*/
void appendOffset(SQLStatement stat, long offset);
/**
* Whether memory tables are supported.
*
* @return true if they are
*/
boolean supportsMemoryTables();
/**
* Whether merge is a supported function.
*
* @return true if they are
*/
boolean supportsMerge();
/**
* Whether LIMIT/OFFSET notation is supported.
*
* @return true if they are
*/
boolean supportsLimitOffset();
/**
* Default implementation of an SQL dialect.
* Does not support merge nor index creation.
*/
public static class DefaultSQLDialect implements SQLDialect {
float databaseVersion;
String productName;
String productVersion;
@Override
public String toString() {
return getClass().getName() + ": " + productName + " " + productVersion;
}
@Override
public void configureDialect(Connection conn) {
loadIdentity(conn);
}
protected void loadIdentity(Connection conn) {
try {
DatabaseMetaData data = conn.getMetaData();
databaseVersion = Float.parseFloat(data.getDatabaseMajorVersion() + "."
+ data.getDatabaseMinorVersion());
productName = data.getDatabaseProductName();
productVersion = data.getDatabaseProductVersion();
} catch (SQLException e) {
throw new IciqlException(e);
}
}
@Override
public boolean supportsMemoryTables() {
return false;
}
@Override
public boolean supportsMerge() {
return false;
}
@Override
public boolean supportsLimitOffset() {
return true;
}
@Override
public String prepareTableName(String schema, String table) {
if (StringUtils.isNullOrEmpty(schema)) {
return table;
}
return schema + "." + table;
}
@Override
public String prepareColumnName(String name) {
return name;
}
@Override
public String prepareCreateIndex(String schema, String table, IndexDefinition index) {
throw new IciqlException("Dialect does not support index creation!");
}
@Override
public void appendLimit(SQLStatement stat, long limit) {
stat.appendSQL(" LIMIT " + limit);
}
@Override
public void appendOffset(SQLStatement stat, long offset) {
stat.appendSQL(" OFFSET " + offset);
}
}
/**
* H2 database dialect.
*/
public static class H2Dialect extends DefaultSQLDialect {
@Override
public boolean supportsMemoryTables() {
return true;
}
@Override
public boolean supportsMerge() {
return true;
}
@Override
public String prepareCreateIndex(String schema, String table, IndexDefinition index) {
StatementBuilder buff = new StatementBuilder();
buff.append("CREATE ");
switch (index.type) {
case STANDARD:
break;
case UNIQUE:
buff.append("UNIQUE ");
break;
case HASH:
buff.append("HASH ");
break;
case UNIQUE_HASH:
buff.append("UNIQUE HASH ");
break;
}
buff.append("INDEX IF NOT EXISTS ");
buff.append(index.indexName);
buff.append(" ON ");
buff.append(table);
buff.append("(");
for (String col : index.columnNames) {
buff.appendExceptFirst(", ");
buff.append(col);
}
buff.append(")");
return buff.toString();
}
}
}
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