jsqlparser解析子查询sql

以下是使用jsqlparser解析子查询sql的示例代码：

import java.io.StringReader;
import java.util.List;

import net.sf.jsqlparser.JSQLParserException;
import net.sf.jsqlparser.expression.Expression;
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.statement.Statement;
import net.sf.jsqlparser.statement.select.PlainSelect;
import net.sf.jsqlparser.statement.select.Select;
import net.sf.jsqlparser.statement.select.SubSelect;

public class JSqlParserDemo {
    public static void main(String[] args) throws JSQLParserException {
        String sql = "SELECT * FROM (SELECT * FROM table1 WHERE id IN (SELECT id FROM table2)) AS subquery";
        Statement statement = CCJSqlParserUtil.parse(sql);
        Select selectStatement = (Select) statement;
        PlainSelect plainSelect = (PlainSelect) selectStatement.getSelectBody();        SubSelect subSelect = (SubSelect) plainSelect.getFromItem();
        Select subquery = (Select) subSelect.getSelectBody();
        PlainSelect subqueryPlainSelect = (PlainSelect) subquery.getSelectBody();
        List<Expression> expressions = subqueryPlainSelect.getSelectItems();
        for (Expression expression : expressions) {
            System.out.println(expression.toString());
        }
    }
}

上述代码中，我们首先将子查询sql语句作为字符串传入JSqlParser进行解析。然后，我们通过获取Select对象和PlainSelect对象来获取子查询的Select对象和PlainSelect对象。最后，我们可以通过获取子查询的PlainSelect对象来获取子查询中的Select字段。