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

Use C# to parse SQL code and create syntax trees

Question:

How to parse SQL code in C# to generate a tree structure that represents the syntax of the code and contains information about the type of statement each node represents?

Answer:

Microsoft.SqlServer.Management.SqlParser.Parser namespace

For Transact-SQL (Microsoft SQL Server), the Microsoft.SqlServer.Management.SqlParser.Parser namespace provides a powerful parsing solution. Here is an example method that parses a T-SQL string into a sequence of tokens:

IEnumerable<TokenInfo> ParseSql(string sql)
{
    ParseOptions parseOptions = new ParseOptions();
    Scanner scanner = new Scanner(parseOptions);

    int state = 0,
        start,
        end,
        lastTokenEnd = -1,
        token;
    bool isPairMatch, isExecAutoParamHelp;

    List<TokenInfo> tokens = new List<TokenInfo>();

    scanner.SetSource(sql, 0);

    while ((token = scanner.GetNext(ref state, out start, out end, out isPairMatch, out isExecAutoParamHelp)) != (int)Tokens.EOF)
    {
        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;
}

Note:

• TokenInfo is a custom class whose properties represent the marker's position, SQL text, and marker type.
• Tokens is an enumeration containing constants representing different tag types (e.g., TOKEN_BEGIN, TOKEN_COMMIT).

Important Tips:

The

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

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