Returning table with CLR

Question

I want to write an CLR procedure which takes a text and returns a table with all the words in this text. But I can\'t figure out how to return a table. Could you please tell me

Answer 1

You can return any list that implements an IEnumerable. Check this out.

Answer 2

Here is a full blown sample. I got tired of searching for this myself and even though this is answered, I thought I would post this just to keep a fresh reference online.

using System;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
using System.Text.RegularExpressions;
using System.Collections;
using System.Collections.Generic;

public partial class UserDefinedFunctions {    
  [SqlFunction]
  public static SqlBoolean RegexPatternMatch(string Input, string Pattern) {    
    return Regex.Match(Input, Pattern).Success ? new SqlBoolean(true) : new SqlBoolean(false);
  }

  [SqlFunction]
  public static SqlString RegexGroupValue(string Input, string Pattern, int GroupNumber) {

    Match m = Regex.Match(Input, Pattern);
    SqlString value = m.Success ? m.Groups[GroupNumber].Value : null;

    return value;
  }

  [SqlFunction(DataAccess = DataAccessKind.Read, FillRowMethodName = "FillMatches", TableDefinition = "GroupNumber int, MatchText nvarchar(4000)")]
  public static IEnumerable RegexGroupValues(string Input, string Pattern) {
    List<RegexMatch> GroupCollection = new List<RegexMatch>();

    Match m = Regex.Match(Input, Pattern);
    if (m.Success) {
      for (int i = 0; i < m.Groups.Count; i++) {
        GroupCollection.Add(new RegexMatch(i, m.Groups[i].Value));
      }
    }

    return GroupCollection;
  }

  public static void FillMatches(object Group, out SqlInt32 GroupNumber, out SqlString MatchText) {
    RegexMatch rm = (RegexMatch)Group;
    GroupNumber = rm.GroupNumber;
    MatchText = rm.MatchText;
  }

  private class RegexMatch {
    public SqlInt32 GroupNumber { get; set; }
    public SqlString MatchText { get; set; }

    public RegexMatch(SqlInt32 group, SqlString match) {
      this.GroupNumber = group;
      this.MatchText = match;
    }
  }
};

Answer 3

This is a new area of SQL Server, you should consult this article. Which shows the syntax of a table-valued function -- that is what you want to create.

Answer 4

    [SqlFunction(DataAccess = DataAccessKind.Read, FillRowMethodName = "FillMatches", TableDefinition = "GroupNumber int, MatchText nvarchar(4000)")]
public static IEnumerable Findall(string Pattern, string Input)
{
    List<RegexMatch> GroupCollection = new List<RegexMatch>();

    Regex regex = new Regex(Pattern);
    if (regex.Match(Input).Success)
    {
        int i = 0;
        foreach (Match match in regex.Matches(Input))
        {
            GroupCollection.Add(new RegexMatch(i, match.Groups[0].Value));
            i++;
        }
    }
    return GroupCollection;
}

That was a slight alteration from the code by "Damon Drake"
This one does a findall instead of returning the first value found. so

declare @txt varchar(100) = 'Race Stat 2017-2018 -(FINAL)';
select * from dbo.findall('(\d+)', @txt)

returns