Apache Calcite进行SQL解析(java代码实例)

Calcite是一款开源SQL解析工具, 可以将各种SQL语句解析成抽象语法树AST(Abstract Syntax Tree), 之后通过操作AST就可以把SQL中所要表达的算法与关系体现在具体代码之中，今天通过代码实例给大家介绍Apache Calcite进行SQL解析问题，感兴趣的朋友一起看看吧

背景

当一个项目分了很多模块，很多个服务的时候，一些公共的配置就需要统一管理了，于是就有了元数据驱动！

简介

什么是Calcite？
是一款开源SQL解析工具, 可以将各种SQL语句解析成抽象语法树AST(Abstract Syntax Tree), 之后通过操作AST就可以把SQL中所要表达的算法与关系体现在具体代码之中。
Calcite能做啥？

• SQL 解析
• SQL 校验
• 查询优化
• SQL 生成器
• 数据连接

实例

今天主要是贴出一个java代码实例，实现了：解析SQL语句中的表名
上代码：
SQL语句转化：

public static SqlNode parseStatement(String sql) {
        SqlParser parser = SqlParser.create(sql, config.getParserConfig());
        try {
            return parser.parseQuery();
        } catch (Exception e) {
            e.printStackTrace();
            throw new UnsupportedOperationException("operation not allowed");
        }
    }

解析Select中的表名：

private static Set<String> extractSourceTableInSelectSql(SqlNode sqlNode, boolean fromOrJoin) {
        if (sqlNode == null) {
            return new HashSet<>();
        }
        final SqlKind sqlKind = sqlNode.getKind();
        if (SqlKind.SELECT.equals(sqlKind)) {
            SqlSelect selectNode = (SqlSelect) sqlNode;
            Set<String> selectList = new HashSet<>(extractSourceTableInSelectSql(selectNode.getFrom(), true));
            selectNode.getSelectList().getList().stream().filter(node -> node instanceof SqlCall)
                .forEach(node -> selectList.addAll(extractSourceTableInSelectSql(node, false)));
            selectList.addAll(extractSourceTableInSelectSql(selectNode.getWhere(), false));
            selectList.addAll(extractSourceTableInSelectSql(selectNode.getHaving(), false));
            return selectList;
        if (SqlKind.JOIN.equals(sqlKind)) {
            SqlJoin sqlJoin = (SqlJoin) sqlNode;
            Set<String> joinList = new HashSet<>();
            joinList.addAll(extractSourceTableInSelectSql(sqlJoin.getLeft(), true));
            joinList.addAll(extractSourceTableInSelectSql(sqlJoin.getRight(), true));
            return joinList;

        if (SqlKind.AS.equals(sqlKind)) {
            SqlCall sqlCall = (SqlCall) sqlNode;
            return extractSourceTableInSelectSql(sqlCall.getOperandList().get(0), fromOrJoin);
        if (SqlKind.IDENTIFIER.equals(sqlKind)) {
            Set<String> identifierList = new HashSet<>();
            if (fromOrJoin) {
                SqlIdentifier sqlIdentifier = (SqlIdentifier) sqlNode;
                identifierList.add(sqlIdentifier.toString());
            }
            return identifierList;
        Set<String> defaultList = new HashSet<>();
        if (sqlNode instanceof SqlCall) {
            SqlCall call = (SqlCall) sqlNode;
            call.getOperandList()
                .forEach(node -> defaultList.addAll(extractSourceTableInSelectSql(node, false)));
        return defaultList;
    }

解析Insert语句中的表名：

private static Set<String> extractSourceTableInInsertSql(SqlNode sqlNode, boolean fromOrJoin) {
        SqlInsert sqlInsert = (SqlInsert) sqlNode;
        Set<String> insertList = new HashSet<>(extractSourceTableInSelectSql(sqlInsert.getSource(), false));
        final SqlNode targetTable = sqlInsert.getTargetTable();
        if (targetTable instanceof SqlIdentifier) {
            insertList.add(((SqlIdentifier) targetTable).toString());
        }
        return insertList;
    }

执行效果

private static final String sql0 = "SELECT MIN(relation_id) FROM tableA JOIN TableB  GROUP BY account_instance_id, follow_account_instance_id HAVING COUNT(*)>1";

private static final String sql1 = "SELECT * FROM blog_user_relation a WHERE (a.account_instance_id,a.follow_account_instance_id) IN (SELECT account_instance_id,follow_account_instance_id FROM Blogs_info GROUP BY account_instance_id, follow_account_instance_id HAVING COUNT(*) > 1)";
private static final String sql2 = "select name from (select * from student)";
private static final String sql3 = "SELECT * FROM Student LEFT JOIN Grade ON Student.sID = Grade.gID\n" +
            "UNION\n" +
            "SELECT * FROM Student RIGHT JOIN Grade ON Student.sID = Grade.gID";
private static final String sql4 = "SELECT *\n" +
            "FROM teacher\n" +
            "WHERE birth = (SELECT MIN(birth)\n" +
            "               FROM employee)";
private static final String sql5 = "SELECT sName\n" +
            "FROM Student\n" +
            "WHERE '450' NOT IN (SELECT courseID\n" +
            "                    FROM Course\n" +
            "                    WHERE sID = Student.sID)";
final SqlNode sqlNode0 = parseStatement(sql0);
System.out.println("sqlNode0: " + extractSourceTableInSelectSql(sqlNode0, false));

结果为：

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