jsqlParser例子(一)where

一、单条件等于查询

public void testParseWhere(){
        String sql = "select *from A as a left join B on a.bid = B.id left join C on A.cid = C.id left join D on B.did = D.id where a.id = 23";
        try {
            Select select = (Select)CCJSqlParserUtil.parse(sql);
            SelectBody selectBody = select.getSelectBody();
            PlainSelect plainSelect = (PlainSelect)selectBody;

            Expression where = plainSelect.getWhere();
            ExpressionDeParser expressionDeParser = new ExpressionDeParser();
            plainSelect.getWhere().accept(expressionDeParser);

            // 此处根据where实际情况强转 最外层
            EqualsTo equalsTo = (EqualsTo)where;
            System.out.println("Table:"+((Column)equalsTo.getLeftExpression()).getTable());
            System.out.println("Field:"+((Column)equalsTo.getLeftExpression()).getColumnName());
            System.out.println("equal:"+equalsTo.getRightExpression());

        } catch (JSQLParserException e) {
            e.printStackTrace();
        }
    }

由于单条件等于，返回为EqualsTo，根据EqualsTo获得表名，列名，及对应单条件值.

二、两个条件or连接

public void testParseWhere(){
        String sql = "select *from A as a left join B on a.bid = B.id left join C on A.cid = C.id left join D on B.did = D.id where a.id = 23 or b.id = 34";
        try {
            Select select = (Select)CCJSqlParserUtil.parse(sql);
            SelectBody selectBody = select.getSelectBody();
            PlainSelect plainSelect = (PlainSelect)selectBody;

            Expression where = plainSelect.getWhere();
            ExpressionDeParser expressionDeParser = new ExpressionDeParser();
            plainSelect.getWhere().accept(expressionDeParser);

            // 此处根据where实际情况强转 最外层
            OrExpression orExpression = (OrExpression)where;
            EqualsTo equalsTo = (EqualsTo)orExpression.getLeftExpression();

            System.out.println("Table:"+((Column)equalsTo.getLeftExpression()).getTable());
            System.out.println("Field:"+((Column)equalsTo.getLeftExpression()).getColumnName());
            System.out.println("equal:"+equalsTo.getRightExpression());
            System.out.println("-----------------");
            equalsTo = (EqualsTo)orExpression.getRightExpression();

            System.out.println("Table:"+((Column)equalsTo.getLeftExpression()).getTable());
            System.out.println("Field:"+((Column)equalsTo.getLeftExpression()).getColumnName());
            System.out.println("equal:"+equalsTo.getRightExpression());

        } catch (JSQLParserException e) {
            e.printStackTrace();
        }
    }

代码中有两个条件or连接，可回忆转成OrExpression,里面还是两个EqualsTo。

三、三个条件or连接

public void testParseWhere(){
        String sql = "select *from A as a left join B on a.bid = B.id left join C on A.cid = C.id left join D on B.did = D.id where a.id = 23 or b.id = 34 or c.id = 54";
        try {
            Select select = (Select)CCJSqlParserUtil.parse(sql);
            SelectBody selectBody = select.getSelectBody();
            PlainSelect plainSelect = (PlainSelect)selectBody;

            Expression where = plainSelect.getWhere();
            ExpressionDeParser expressionDeParser = new ExpressionDeParser();
            plainSelect.getWhere().accept(expressionDeParser);

            // 此处根据where实际情况强转 最外层
            OrExpression orExpression = (OrExpression)where;

            OrExpression leftOrExpression = (OrExpression)orExpression.getLeftExpression();

            EqualsTo equalsTo = (EqualsTo)leftOrExpression.getLeftExpression();

            System.out.println("Table:"+((Column)equalsTo.getLeftExpression()).getTable());
            System.out.println("Field:"+((Column)equalsTo.getLeftExpression()).getColumnName());
            System.out.println("equal:"+equalsTo.getRightExpression());
            System.out.println("-----------------");
            equalsTo = (EqualsTo)leftOrExpression.getRightExpression();

            System.out.println("Table:"+((Column)equalsTo.getLeftExpression()).getTable());
            System.out.println("Field:"+((Column)equalsTo.getLeftExpression()).getColumnName());
            System.out.println("equal:"+equalsTo.getRightExpression());
            System.out.println("-----------------");
            equalsTo = (EqualsTo)orExpression.getRightExpression();

            System.out.println("Table:"+((Column)equalsTo.getLeftExpression()).getTable());
            System.out.println("Field:"+((Column)equalsTo.getLeftExpression()).getColumnName());
            System.out.println("equal:"+equalsTo.getRightExpression());

        } catch (JSQLParserException e) {
            e.printStackTrace();
        }
    }

得到的第一层的leftExpression还是一个orExpression,rightExpression是一个EqualsTo