c# - List of tables used in an SQL Query

Question

Is there a way how to get a list of tables used within an SQL query? Example : I have something like :

SELECT * FROM Table t JOIN OtherTable ON t.id=OtherTable.t_id

and I would expect to get

Table, OtherTable

Thanks

Answer 1

One solution using C# is to import Microsoft.SqlServer.TransactSql.ScriptDom (I found the dll at C:Program Files (x86)Microsoft SQL Server120SDKAssembliesMicrosoft.SqlServer.TransactSql.ScriptDom.dll) then do the following:

private List<string> GetTableNamesFromQueryString(string query)
{
    IList<ParseError> errors = new List<ParseError>();
    IList<TSqlParserToken> queryTokens;
    List<string> output = new List<string>(16);
    StringBuilder sb = new StringBuilder(128);
    TSql120Parser parser = new TSql120Parser(true);
    TSqlTokenType[] fromTokenTypes = new TSqlTokenType[2]
        {
            TSqlTokenType.From,
            TSqlTokenType.Join
        };
    TSqlTokenType[] identifierTokenTypes = new TSqlTokenType[2]
        {
            TSqlTokenType.Identifier,
            TSqlTokenType.QuotedIdentifier
        };

    using (System.IO.TextReader tReader = new System.IO.StringReader(query))
    {
        queryTokens = parser.GetTokenStream(tReader, out errors);
        if (errors.Count > 0) { return errors.Select(e=>"Error: " + e.Number + " Line: " + e.Line + " Column: " + e.Column + " Offset: " + e.Offset + " Message: " + e.Message).ToList(); }

        for (int i = 0; i < queryTokens.Count; i++)
        {
            if(fromTokenTypes.Contains(queryTokens[i].TokenType))
            {
                for (int j = i + 1; j < queryTokens.Count; j++)
                {
                    if (queryTokens[j].TokenType == TSqlTokenType.WhiteSpace) { continue; }
                    else if (identifierTokenTypes.Contains(queryTokens[j].TokenType))
                    {
                        sb.Clear();

                        GetQuotedIdentifier(queryTokens[j], sb);            //Change Identifiers to QuotedIdentifier (text only)

                        while (j + 2 < queryTokens.Count && queryTokens[j + 1].TokenType == TSqlTokenType.Dot && identifierTokenTypes.Contains(queryTokens[j + 2].TokenType))
                        {
                            sb.Append(queryTokens[j + 1].Text);
                            GetQuotedIdentifier(queryTokens[j + 2], sb);    //Change Identifiers to QuotedIdentifier (text only)

                            j += 2;
                        }

                        output.Add(sb.ToString());
                        break;              //exit the loop
                    }
                    else { break; }             //exit the loop if token is not a FROM, a JOIN, or white space.
                }

            }
        }

        return output.Distinct().OrderBy(tableName => tableName).ToList();
    }
}

private void GetQuotedIdentifier(TSqlParserToken token, StringBuilder sb)
{
    switch(token.TokenType)
    {
        case TSqlTokenType.Identifier: sb.Append('[').Append(token.Text).Append(']'); return;
        case TSqlTokenType.QuotedIdentifier: sb.Append(token.Text); return;
        default: throw new ArgumentException("Error: expected TokenType of token should be TSqlTokenType.Identifier or TSqlTokenType.QuotedIdentifier");
    }
}

I came up with this after trying to get this answer to work.