How Can I Parse SQL Code in C# to Extract a Syntax Tree?

Use C# to parse SQL code and extract syntax tree

Goal

The goal of this article is to use C# to parse SQL code to extract a syntax tree or other meaningful structure and identify the statement type represented by each node in the tree.

Microsoft.SqlServer.Management.SqlParser.Parser namespace

For Transact-SQL (Microsoft SQL Server), the Microsoft.SqlServer.Management.SqlParser.Parser namespace is free to use and provides SQL code parsing capabilities.

T-SQL parsing example method

Here is an example method that parses T-SQL stored in a string into a sequence of tokens:

<code class="language-csharp">IEnumerable<TokenInfo> ParseSql(string sql)
{
    // 解析选项和扫描器初始化
    ParseOptions parseOptions = new ParseOptions();
    Scanner scanner = new Scanner(parseOptions);

    // 解析变量和结果集合
    int state = 0,
        start,
        end,
        lastTokenEnd = -1,
        token;

    bool isPairMatch, isExecAutoParamHelp;
    List<TokenInfo> tokens = new List<TokenInfo>();

    scanner.SetSource(sql, 0);

    // 标记提取循环
    while ((token = scanner.GetNext(ref state, out start, out end, out isPairMatch, out isExecAutoParamHelp)) != (int)Tokens.EOF)
    {
        // 创建标记信息
        TokenInfo tokenInfo = new TokenInfo()
        {
            Start = start,
            End = end,
            IsPairMatch = isPairMatch,
            IsExecAutoParamHelp = isExecAutoParamHelp,
            Sql = sql.Substring(start, end - start + 1),
            Token = (Tokens)token,
        };

        tokens.Add(tokenInfo);
        lastTokenEnd = end;
    }

    return tokens;
}</code>

Please note that TokenInfo is a simple class whose properties correspond to token information. Tokens is an enumeration of token types (e.g., TOKEN_BEGIN, TOKEN_COMMIT).

NuGet package

Microsoft.SqlServer.Management.SqlParser namespace is now available as a separate NuGet package: https://www.php.cn/link/e6e8bbe351bf19f963820a96543f25db.

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