/*
* Copyright 1999-2017 Alibaba Group Holding Ltd.
*
* 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.alibaba.druid.support.opds.udf;
import java.util.List;
import com.alibaba.druid.sql.SQLUtils;
import com.alibaba.druid.sql.ast.SQLStatement;
import com.alibaba.druid.sql.visitor.SchemaStatVisitor;
import com.alibaba.druid.stat.TableStat;
import com.aliyun.odps.udf.UDF;
public class ExportColumns extends UDF {
public String evaluate(String sql) {
return evaluate(sql, null);
}
public String evaluate(String sql, String dbType) {
try {
List<SQLStatement> statementList = SQLUtils.parseStatements(sql, dbType);
SchemaStatVisitor visitor = SQLUtils.createSchemaStatVisitor(dbType);
for (SQLStatement stmt : statementList) {
stmt.accept(visitor);
}
StringBuffer buf = new StringBuffer();
for (TableStat.Column column : visitor.getColumns()) {
if (buf.length() != 0) {
buf.append(',');
}
buf.append(column.toString());
}
return buf.toString();
} catch (Throwable ex) {
System.err.println("error sql : " + sql);
ex.printStackTrace();
return null;
}
}
}