Function Parsing

1. Add the Dependency

<dependency>
    <groupId>com.dtstack</groupId>
    <artifactId>sqlparserx-core</artifactId>
    <version>1.0-SNAPSHOT</version>
</dependency>

sqlparserx-core transitively brings in sqlparserx-syntax and Druid.

2. Complete Example

Using the official sqlparserx-core/README.md sample SQL to extract the set of functions:

FunctionParseDemo.java

import com.dtstack.sqlparserx.core.parser.ISqlParser;
import com.dtstack.sqlparserx.core.parser.SqlParserFactory;

import com.alibaba.druid.DbType;

import java.util.Set;

public class FunctionParseDemo {

    public static void main(String[] args) {
        String sql = "CREATE TABLE user_order_summary AS\n"
                + "SELECT\n"
                + "    u.id as user_id,\n"
                + "    u.name,\n"
                + "    SUM(o.amount) as total_amount,\n"
                + "    COUNT(o.id) as order_count\n"
                + "FROM users u JOIN orders o ON u.id = o.user_id\n"
                + "GROUP BY u.id, u.name";

        // 1. Get a parser
        ISqlParser parser = SqlParserFactory.getSqlParser(DbType.mysql);

        // 2. Parse functions used in the SQL
        Set<String> functions = parser.parseFunction(sql);

        // 3. Read the result
        System.out.println("functions: " + functions);
    }
}

Console output (example):

functions: [sum, count]

3. Goal

Extract function calls from SQL as a de-duplicated set of function names for function-level governance and dependency analysis.

SQLStatement AST
  → BaseSqlParser.parseFunction
  → traverse AST to collect function expressions
  → Set<String> functions

4. Entry & Implementation

Item	Content
Core entry	ISqlParser.parseFunction(sql)
Default impl	BaseSqlParser.parseFunction
Return type	Set<String> (function names, lower-cased)
Coverage	built-in, aggregate, window, custom functions

5. Supported Scenarios

Capability	Status	Notes
Regular function calls	Supported ✅	e.g. substr(name, 1, 3)
Aggregate functions	Supported ✅	e.g. sum, count, max
Window functions	Supported ✅	e.g. row_number() over(...)
Nested functions	Supported ✅	Recursively collect inner and outer functions