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String Utility Functions Sample

The String Utilities sample contains a streaming table-valued function written in Visual C# and Visual Basic, which splits a comma-separated string into a table with one column. It also contains an aggregate function that converts a string column to a comma-separated string. Also implemented are a scalar function and a table-valued function that provide regular expression replacement and regular expression searching functionality.

To implement a streaming table-valued function, create a method that returns an object that implements the IEnumerable interface. This IEnumerable method must be linked by an attribute to another method which fills in rows of the table-valued function.

To create and run this project the following the following software must be installed:

  • SQL Server or SQL Server Express. You can obtain SQL Server Express free of charge from the SQL Server Express Documentation and Samples Web site

  • The AdventureWorks database that is available at the SQL Server Developer Web site

  • .NET Framework SDK 2.0 or later or Microsoft Visual Studio 2005 or later. You can obtain .NET Framework SDK free of charge.

  • In addition, the following conditions must be met:

  • The SQL Server instance you are using must have CLR integration enabled.

  • In order to enable CLR integration, perform the following steps:

    Enabling CLR Integration

    • Execute the following Transact-SQL commands:

    sp_configure 'clr enabled', 1

    GO

    RECONFIGURE

    GO

    Note Note

    To enable CLR integration, you must have ALTER SETTINGS server level permission, which is implicitly held by members of the sysadmin and serveradmin fixed server roles.

  • The AdventureWorks database must be installed on the SQL Server instance you are using.

  • If you are not an administrator for the SQL Server instance you are using, you must have an administrator grant you CreateAssembly permission to complete the installation.

Create and run the sample by using the following instructions:

  1. Open a Visual Studio or .NET Framework command prompt.

  2. If necessary, create a directory for your sample. For this example, we will use C:\MySample.

  3. In c:\MySample, create StringUtils.vb (for the Visual Basic sample) or StringUtils.cs (for the C# sample) and copy the appropriate Visual Basic or C# sample code (below) into the file.

  4. Compile the sample code from the command line prompt by executing one of the following, depending on your choice of language.

    • Vbc /target:library /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\v3.5\System.Core.dll",C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Data.dll,C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.dll,C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Xml.dll /debug- /target:library StringUtils.vb

    • Csc/reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Data.dll /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.dll /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.XML.dll /target:library StringUtils.cs

  5. Copy the Transact-SQL installation code into a file and save it as Install.sql in the sample directory.

  6. If the sample is installed in a directory other then C:\MySample\, edit the file Install.sql as indicated to point to that location.

  7. Deploy the assembly and stored procedure by executing

    • sqlcmd -E -I -i install.sql

    • Copy Transact-SQL test command script into a file and save it as test.sql in the sample directory.

  8. Execute the test script with the following command

    • sqlcmd -E -I -i test.sql

  9. Copy the Transact-SQL cleanup script into a file and save it as cleanup.sql in the sample directory.

  10. Execute the script with the following command

    • sqlcmd -E -I -i cleanup.sql

The following are the code listings for this sample.

C#

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

    /// <summary>
    /// This class is provides regular expression operations for Transact-SQL callers
    /// </summary>
    public sealed class RegularExpression
    {
        private RegularExpression()
        {

        }

        /// <summary>
        /// This method returns a table of matches, groups, and captures based on the input
        /// string and pattern string provided.
        /// </summary>
        /// <param name="sqlInput">What to match against</param>
        /// <param name="sqlPattern">What to look for</param>
        /// <returns>An object which appears to be reading from SQL Server but which in fact is reading
        ///          from a memory based representation of the data.</returns>
        [SqlFunction(FillRowMethodName = "FillRow")]
        public static IEnumerable Matches(SqlString sqlInput, SqlString sqlPattern)
        {
            string input = (sqlInput.IsNull) ? string.Empty : sqlInput.Value;
            string pattern = (sqlPattern.IsNull) ? string.Empty : sqlPattern.Value;

            return GetMatches(input, pattern);
        }

        public static void FillRow(object obj, out int matchId, out int matchIndex, out string matchValue,
            out int groupId, out int groupIndex, out string groupValue, out int captureIndex,
            out string captureValue)
        {
            MatchResult result = (MatchResult)obj;
            matchId = result.MatchID;
            matchIndex = result.MatchIndex;
            matchValue = result.MatchValue;
            groupId = result.GroupID;
            groupIndex = result.GroupIndex;
            groupValue = result.GroupValue;
            captureIndex = result.CaptureIndex;
            captureValue = result.CaptureValue;
        }

        /// <summary>
        ///     Generates a list of Match/Group/Capture tuples represented using the
        ///     MatchResult struct based on the regular expression match of the input
        ///     string and pattern string provided.
        /// </summary>
        /// <param name="input">What to match</param>
        /// <param name="pattern">What to look for</param>
        /// <returns>A list of Match/Group/Capture tuples</returns>
        private static List<MatchResult> GetMatches(string input, string pattern)
        {
            List<MatchResult> result = new List<MatchResult>();
            int matchId = 0;
            int groupId = 0;
            foreach (Match m in Regex.Matches(input, pattern))
            {
                if (m.Groups.Count < 1)
                    result.Add(new MatchResult(matchId, m.Index, m.Value, -1, -1, string.Empty, -1, string.Empty));
                else
                {
                    groupId = 0;
                    foreach (Group g in m.Groups)
                    {
                        if (g.Captures.Count < 1)
                            result.Add(new MatchResult(matchId, m.Index, m.Value,
                                groupId, g.Index, g.Value, -1, string.Empty));
                        else
                        {
                            foreach (Capture c in m.Groups)
                            {
                                result.Add(new MatchResult(matchId, m.Index, m.Value,
                                    groupId, g.Index, g.Value, c.Index, c.Value));
                            }
                        }

                        groupId += 1;
                    }
                }

                matchId += 1;
            }

            return result;
        }

        /// <summary>
        ///     This method performs a pattern based substitution based on the provided input string, pattern
        ///     string, and replacement string.
        /// </summary>
        /// <param name="sqlInput">The source material</param>
        /// <param name="sqlPattern">How to parse the source material</param>
        /// <param name="sqlReplacement">What the output should look like</param>
        /// <returns></returns>
        public static string Replace(SqlString sqlInput, SqlString sqlPattern, SqlString sqlReplacement)
        {
            string input = (sqlInput.IsNull) ? string.Empty : sqlInput.Value;
            string pattern = (sqlPattern.IsNull) ? string.Empty : sqlPattern.Value;
            string replacement = (sqlReplacement.IsNull) ? string.Empty : sqlReplacement.Value;
            return Regex.Replace(input, pattern, replacement);
        }
    }

    /// <summary>
    /// This struct is used trepresents a Match/Group/Capture tuple.  Instances of this struct are
    /// created by the GetMatches method.
    /// </summary>
    internal struct MatchResult
    {
        /// <summary>
        /// Which match this is
        /// </summary>
        private int _matchID;
        public int MatchID
        {
            get
            {
                return this._matchID;
            }
        }

        /// <summary>
        /// Where the match starts in the input string
        /// </summary>
        private int _matchIndex;
        public int MatchIndex
        {
            get
            {
                return this._matchIndex;
            }
        }

        /// <summary>
        /// What string matched the pattern
        /// </summary>
        private string _matchValue;
        public string MatchValue
        {
            get
            {
                return this._matchValue;
            }
        }

        /// <summary>
        /// Which matching group this is
        /// </summary>
        private int _groupID;
        public int GroupID
        {
            get
            {
                return this._groupID;
            }
        }

        /// <summary>
        /// Where this group starts in the input string
        /// </summary>
        private int _groupIndex;
        public int GroupIndex
        {
            get
            {
                return this._groupIndex;
            }
        }

        /// <summary>
        /// What the group matched in the input string
        /// </summary>
        private string _groupValue;
        public string GroupValue
        {
            get
            {
                return this._groupValue;
            }
        }

        /// <summary>
        /// Where this capture starts in the input string
        /// </summary>
        private int _captureIndex;
        public int CaptureIndex
        {
            get
            {
                return this._captureIndex;
            }
        }

        /// <summary>
        /// What the capture matched in the input string
        /// </summary>
        private string _captureValue;
        public string CaptureValue
        {
            get
            {
                return this._captureValue;
            }
        }

        /// <summary>
        ///     A convenient constructor which fills in all the fields contained in this struct.
        /// </summary>
        /// <param name="matchID">Which match this is</param>
        /// <param name="matchIndex">Where the match starts in the input string</param>
        /// <param name="matchValue">What string matched the pattern</param>
        /// <param name="groupID">Which matching group this is</param>
        /// <param name="groupIndex">Where this group starts in the input string</param>
        /// <param name="groupValue">What the group matched in the input string</param>
        /// <param name="captureIndex">Where this capture starts in the input string</param>
        /// <param name="captureValue">What the capture matched in the input string</param>
        public MatchResult(int matchId, int matchIndex, string matchValue,
            int groupId, int groupIndex, string groupValue,
            int captureIndex, string captureValue)
        {
            this._matchID = matchId;
            this._matchIndex = matchIndex;
            this._matchValue = matchValue;
            this._groupID = groupId;
            this._groupIndex = groupIndex;
            this._groupValue = groupValue;
            this._captureIndex = captureIndex;
            this._captureValue = captureValue;
        }
    }


    public sealed class StringSplitter
    {

        /// <summary>
        /// The streaming table-valued function used to split the string into a relation
        /// </summary>
        /// <param name="argument"></param>
        /// <returns></returns>
        [SqlFunction(FillRowMethodName = "FillRow")]
        public static IEnumerable Split(SqlString argument)
        {
            string value;
            if (argument.IsNull)
                value = "";
            else
                value = argument.Value;
            return value.Split(',');
        }

        public static void FillRow(Object obj, out string stringElement)
        {
            stringElement = (string)obj;
        }

        /// <summary>
        /// Don't allow callers to create instances of this class
        /// </summary>
        private StringSplitter() { }
    }
    [Serializable]
    [Microsoft.SqlServer.Server.SqlUserDefinedAggregate(
        Microsoft.SqlServer.Server.Format.UserDefined, //use clr serialization to serialize the intermediate result
        IsInvariantToNulls = true,//optimizer property
        IsInvariantToDuplicates = false,//optimizer property
        IsInvariantToOrder = false,//optimizer property
        MaxByteSize = 8000)//maximum size in bytes of persisted value
        ]
    public class Concatenate : Microsoft.SqlServer.Server.IBinarySerialize
    {
        /// <summary>
        /// The variable that holds the intermediate result of the concatenation
        /// </summary>
        private StringBuilder intermediateResult;

        /// <summary>
        /// Initialize the internal data structures
        /// </summary>
        public void Init()
        {
            intermediateResult = new StringBuilder();
        }

        /// <summary>
        /// Accumulate the next value, nop if the value is null
        /// </summary>
        /// <param name="value"></param>
        public void Accumulate(SqlString value)
        {

            if (value.IsNull)
            {
                return;
            }
            intermediateResult.Append(value.Value).Append(',');

        }

        /// <summary>
        /// Merge the partially computed aggregate with this aggregate.
        /// </summary>
        /// <param name="other"></param>
        public void Merge(Concatenate other)
        {
            intermediateResult.Append(other.intermediateResult);
        }

        /// <summary>
        /// Called at the end of aggregation, to return the results of the aggregation
        /// </summary>
        /// <returns></returns>
        public SqlString Terminate()
        {
            string output = string.Empty;
            //delete the trailing comma, if any
            if (intermediateResult != null && intermediateResult.Length > 0)
                output = intermediateResult.ToString(0, intermediateResult.Length - 1);
            return new SqlString(output);
        }

        public void Read(BinaryReader r)
        {
            if (r == null) throw new ArgumentNullException("r");
            intermediateResult = new StringBuilder(r.ReadString());
        }

        public void Write(BinaryWriter w)
        {
            if (w == null) throw new ArgumentNullException("w");
            w.Write(intermediateResult.ToString());
        }
    }

VB.NET

Imports Microsoft.VisualBasic
Imports Microsoft.SqlServer.Server
Imports System
Imports System.Collections
Imports System.Collections.Generic
Imports System.Data
Imports System.Data.SqlTypes
Imports System.Diagnostics
Imports System.IO
Imports System.Linq
Imports System.Runtime.InteropServices
Imports System.Text
Imports System.Text.RegularExpressions


<Serializable(), Microsoft.SqlServer.Server.SqlUserDefinedAggregate(Microsoft.SqlServer.Server.Format.UserDefined, IsInvariantToNulls:=True, IsInvariantToDuplicates:=False, IsInvariantToOrder:=False, MaxByteSize:=8000)> _
Public Class Concatenate
    'use clr serialization to serialize the intermediate result
    'optimizer property
    'optimizer property
    'optimizer property
    'maximum size in bytes of persisted value
    Implements Microsoft.SqlServer.Server.IBinarySerialize

    ''' <summary>
    ''' The variable that holds the intermediate result of the concatenation
    ''' </summary>
    Private intermediateResult As StringBuilder

    ''' <summary>
    ''' Initialize the internal data structures
    ''' </summary>
    Public Sub Init()
        intermediateResult = New StringBuilder()
    End Sub

    ''' <summary>
    ''' Accumulate the next value, nop if the value is null
    ''' </summary>
    ''' <param name="value"></param>
    Public Sub Accumulate(ByVal value As SqlString)
        If value.IsNull Then
            Return
        End If

        intermediateResult.Append(value.Value).Append(","c)
    End Sub

    ''' <summary>
    ''' Merge the partially computed aggregate with this aggregate.
    ''' </summary>
    ''' <param name="other"></param>
    Public Sub Merge(ByVal other As Concatenate)
        intermediateResult.Append(other.intermediateResult)
    End Sub

    ''' <summary>
    ''' Called at the end of aggregation, to return the results of the aggregation
    ''' </summary>
    ''' <returns></returns>
    Public Function Terminate() As SqlString
        Dim output As String = String.Empty

        'delete the trailing comma, if any
        If Not (intermediateResult Is Nothing) AndAlso intermediateResult.Length > 0 Then
            output = intermediateResult.ToString(0, intermediateResult.Length - 1)
        End If

        Return New SqlString(output)
    End Function

    Public Sub Read(ByVal r As BinaryReader) Implements Microsoft.SqlServer.Server.IBinarySerialize.Read
        If r Is Nothing Then
            Throw New ArgumentNullException("r")
        End If
        intermediateResult = New StringBuilder(r.ReadString())
    End Sub

    Public Sub Write(ByVal w As BinaryWriter) Implements Microsoft.SqlServer.Server.IBinarySerialize.Write
        If w Is Nothing Then
            Throw New ArgumentNullException("w")
        End If
        w.Write(intermediateResult.ToString())
    End Sub
End Class

Public NotInheritable Class RegularExpression

    Private Sub New()
    End Sub

    ''' <summary>
    ''' This method returns a table of matches, groups, and captures based on the input
    ''' string and pattern string provided.
    ''' </summary>
    ''' <param name="sqlInput">What to match against</param>
    ''' <param name="sqlPattern">What to look for</param>
    ''' <returns>An object which appears to be reading from SQL Server but which in fact is reading
    '''          from a memory based representation of the data.</returns>
    <SqlFunction(Name:="RegexMatches", FillRowMethodName:="FillMatchRow", _
        TableDefinition:="MatchID int, MatchIndex int, MatchValue nvarchar(4000), GroupID int, GroupIndex int, GroupValue nvarchar(4000), CaptureIndex int, CaptureValue nvarchar(4000)")> _
    Public Shared Function Matches(ByVal sqlInput As SqlString, ByVal sqlPattern As SqlString) As IEnumerable
        Dim input As String = String.Empty
        If Not sqlInput.IsNull Then
            input = sqlInput.Value
        End If

        Dim pattern As String = String.Empty
        If Not sqlPattern.IsNull Then
            pattern = sqlPattern.Value
        End If

        Return GetMatches(input, pattern)
    End Function

    ''' <summary>
    ''' Invoked by SQL Server when returning a row of the TVF.  Splits the MatchResult object into
    ''' the separate pieces of data which will form the columns of the row.
    ''' </summary>
    ''' <param name="row"></param>
    ''' <param name="matchID"></param>
    ''' <param name="matchIndex"></param>
    ''' <param name="matchValue"></param>
    ''' <param name="groupID"></param>
    ''' <param name="groupIndex"></param>
    ''' <param name="groupValue"></param>
    ''' <param name="captureIndex"></param>
    ''' <param name="captureValue"></param>

    Private Shared Sub FillMatchRow(ByVal row As Object, <Out()> ByRef matchId As Integer, _
        <Out()> ByRef matchIndex As Integer, <Out()> ByRef matchValue As String, <Out()> ByRef groupId As Integer, _
        <Out()> ByRef groupIndex As Integer, <Out()> ByRef groupValue As String, <Out()> ByRef captureIndex As Integer, _
        <Out()> ByRef captureValue As String)

        Dim result As MatchResult

        result = CType(row, MatchResult)

        matchId = result.MatchID
        matchIndex = result.MatchIndex
        matchValue = result.MatchValue
        groupId = result.GroupID
        groupIndex = result.GroupIndex
        groupValue = result.GroupValue
        captureIndex = result.CaptureIndex
        captureValue = result.CaptureValue
    End Sub

    ''' <summary>
    '''     Generates a list of Match/Group/Capture tuples represented using the
    '''     MatchResult struct based on the regular expression match of the input
    '''     string and pattern string provided.
    ''' </summary>
    ''' <param name="input">What to match</param>
    ''' <param name="pattern">What to look for</param>
    ''' <returns>A list of Match/Group/Capture tuples</returns>
    Private Shared Function GetMatches(ByVal input As String, ByVal pattern As String) As List(Of MatchResult)
        Dim result As List(Of MatchResult) = New List(Of MatchResult)()
        Dim matchID As Integer = 0
        Dim groupID As Integer = 0

        For Each m As Match In Regex.Matches(input, pattern)
            If m.Groups.Count < 1 Then
                result.Add(New MatchResult(matchID, m.Index, m.Value, -1, -1, _
                    String.Empty, -1, String.Empty))
            Else
                groupID = 0
                For Each g As Group In m.Groups
                    If g.Captures.Count < 1 Then
                        result.Add(New MatchResult(matchID, m.Index, m.Value, _
                            groupID, g.Index, g.Value, -1, String.Empty))
                    Else
                        For Each c As Capture In m.Groups
                            result.Add(New MatchResult(matchID, m.Index, _
                                m.Value, groupID, g.Index, g.Value, c.Index, _
                                c.Value))
                        Next
                    End If

                    groupID += 1
                Next
            End If

            matchID += 1
        Next

        Return result
    End Function

    ''' <summary>
    '''     This method performs a pattern based substitution based on the provided input string, pattern
    '''     string, and replacement string.
    ''' </summary>
    ''' <param name="sqlInput">The source material</param>
    ''' <param name="sqlPattern">How to parse the source material</param>
    ''' <param name="sqlReplacement">What the output should look like</param>
    ''' <returns></returns>
    <SqlFunction(Name:="RegexReplace", DataAccess:=DataAccessKind.None)> _
    Public Shared Function Replace(ByVal sqlInput As SqlString, ByVal sqlPattern As SqlString, ByVal sqlReplacement As SqlString) As String
        Dim input As String = String.Empty

        If Not sqlInput.IsNull Then
            input = sqlInput.Value
        End If

        Dim pattern As String = String.Empty

        If Not sqlPattern.IsNull Then
            pattern = sqlPattern.Value.ToString()
        End If

        Dim replacement As String = String.Empty

        If Not sqlReplacement.IsNull Then
            replacement = sqlReplacement.Value.ToString()
        End If

        Return Regex.Replace(input, pattern, replacement)
    End Function
End Class


''' <summary>
''' This struct is used to represent a Match/Group/Capture tuple.  Instances of 
''' this struct are created by the GetMatches method.
''' </summary>
Friend Structure MatchResult
    ''' <summary>
    ''' Which match this is
    ''' </summary>
    Private _matchID As Integer


    Friend ReadOnly Property MatchID() As Integer
        Get
            Return Me._matchID
        End Get
    End Property

    ''' <summary>
    ''' Where the match starts in the input string
    ''' </summary>
    Private _matchIndex As Integer


    Friend ReadOnly Property MatchIndex() As Integer
        Get
            Return Me._matchIndex
        End Get
    End Property

    ''' <summary>
    ''' What string matched the pattern
    ''' </summary>
    Private _matchValue As String

    Friend ReadOnly Property MatchValue() As String
        Get
            Return Me._matchValue
        End Get
    End Property

    ''' <summary>
    ''' Which matching group this is
    ''' </summary>
    Private _groupID As Integer


    Friend ReadOnly Property GroupID() As Integer
        Get
            Return Me._groupID
        End Get
    End Property

    ''' <summary>
    ''' Where this group starts in the input string
    ''' </summary>
    Private _groupIndex As Integer


    Friend ReadOnly Property GroupIndex() As Integer
        Get
            Return Me._groupIndex
        End Get
    End Property

    ''' <summary>
    ''' What the group matched in the input string
    ''' </summary>
    Private _groupValue As String

    Friend ReadOnly Property GroupValue() As String
        Get
            Return Me._groupValue
        End Get
    End Property

    ''' <summary>
    ''' Where this capture starts in the input string
    ''' </summary>
    Private _captureIndex As Integer


    Friend ReadOnly Property CaptureIndex() As Integer
        Get
            Return Me._captureIndex
        End Get
    End Property

    ''' <summary>
    ''' What the capture matched in the input string
    ''' </summary>
    Private _captureValue As String


    Friend ReadOnly Property CaptureValue() As String
        Get
            Return Me._captureValue
        End Get
    End Property

    ''' <summary>
    '''     A convenient constructor which fills in all the fields contained in this struct.
    ''' </summary>
    ''' <param name="matchID">Which match this is</param>
    ''' <param name="matchIndex">Where the match starts in the input string</param>
    ''' <param name="matchValue">What string matched the pattern</param>
    ''' <param name="groupID">Which matching group this is</param>
    ''' <param name="groupIndex">Where this group starts in the input string</param>
    ''' <param name="groupValue">What the group matched in the input string</param>
    ''' <param name="captureIndex">Where this capture starts in the input string</param>
    ''' <param name="captureValue">What the capture matched in the input string</param>
    Friend Sub New(ByVal matchID As Integer, ByVal matchIndex As Integer, ByVal matchValue As String, ByVal groupID As Integer, ByVal groupIndex As Integer, ByVal groupValue As String, ByVal captureIndex As Integer, ByVal captureValue As String)
        Me._matchID = matchID
        Me._matchIndex = matchIndex
        Me._matchValue = matchValue
        Me._groupID = groupID
        Me._groupIndex = groupIndex
        Me._groupValue = groupValue
        Me._captureIndex = captureIndex
        Me._captureValue = captureValue
    End Sub
End Structure
Public NotInheritable Class StringSplitter

    ''' <summary>
    ''' The streaming table-valued function used to split the string into a relation
    ''' </summary>
    ''' <param name="argument"></param>
    ''' <returns></returns>
    <SqlFunction(Name:="Split", DataAccess:=DataAccessKind.None, FillRowMethodName:="FillSplitRow", _
        TableDefinition:="StringElement nvarchar(128) COLLATE Latin1_General_CI_AS")> _
    Public Shared Function Split(ByVal argument As SqlString) As IEnumerable
        Dim value As String

        If argument.IsNull Then
            value = String.Empty
        Else
            value = argument.Value
        End If

        Return value.Split(","c)
    End Function


    Private Shared Sub FillSplitRow(ByVal row As Object, ByRef stringElement As String)
        stringElement = CType(row, String)
    End Sub

    ''' <summary>
    ''' Don't allow callers to create instances of this class
    ''' </summary>
    Private Sub New()
    End Sub
End Class

This is the Transact-SQL installation script (Install.sql), which deploys the assembly and creates the stored procedure in the database.

USE AdventureWorks
GO

IF OBJECT_ID(N'RegexMatches', N'FT') is not null
DROP Function RegexMatches;
GO

IF OBJECT_ID(N'Split', N'FT') is not null
DROP Function Split;
GO

IF OBJECT_ID(N'RegexReplace', N'FS') is not null
DROP Function RegexReplace;
GO

IF OBJECT_ID(N'Concatenate', N'AF') is not null
DROP Aggregate Concatenate;
GO

IF EXISTS (SELECT * FROM sys.assemblies WHERE [name] = 'StringUtils')
DROP ASSEMBLY StringUtils;
GO

DECLARE @SamplePath nvarchar(1024)
-- You will need to modify the value of the this variable if you have installed the sample someplace other than the default location.
Set @SamplePath = 'C:\MySample\'
CREATE ASSEMBLY [StringUtils] 
FROM @SamplePath + 'StringUtils.dll'
WITH permission_set = Safe;
GO

CREATE AGGREGATE [dbo].[Concatenate](@input nvarchar(4000))
RETURNS nvarchar(4000)
EXTERNAL NAME [StringUtils].[Concatenate];
GO

CREATE FUNCTION [dbo].[Split](@input nvarchar(4000)) 
RETURNS  TABLE(StringElement nvarchar(128) COLLATE Latin1_General_CI_AS)
AS EXTERNAL NAME [StringUtils].[StringSplitter].[Split];
GO

CREATE FUNCTION [RegexMatches] (@input nvarchar(max), @pattern nvarchar(max))
RETURNS TABLE(
MatchID int,
    MatchIndex int,
    MatchValue nvarchar(4000),
GroupID int,
GroupIndex int,
GroupValue nvarchar(4000),
CaptureIndex int,
CaptureValue nvarchar(4000))
AS EXTERNAL NAME [StringUtils].[RegularExpression].[Matches];
GO

CREATE FUNCTION [RegexReplace] (@input nvarchar(max), @pattern nvarchar(max), @replacement nvarchar(max))
RETURNS nvarchar(max)
AS EXTERNAL NAME [StringUtils].[RegularExpression].[Replace]
GO

This is test.sql, which tests the sample by executing the functions.

USE AdventureWorks
GO

-- Invoke the tvf
SELECT * FROM dbo.Split('will,this,work');
GO

-- Invoke the aggregate over the results of the tvf
SELECT dbo.Concatenate(StringElement) FROM dbo.Split('will,this,also,work');
GO

-- Find two word pairs where the first word contains an 'r'
SELECT MatchID, MatchIndex, MatchValue, 
  GroupID, GroupIndex, GroupValue, 
  CaptureIndex, CaptureValue
FROM dbo.RegexMatches('The quick red fox jumped over the lazy brown dog', '(\w*r\w*)\s(\w+)');
GO

-- A variant of the above with no backtracking
SELECT MatchID, MatchIndex, MatchValue, 
  GroupID, GroupIndex, GroupValue, 
  CaptureIndex, CaptureValue
FROM dbo.RegexMatches('The quick red fox jumped over the lazy brown dog', '(?>\w*r\w*)\s(?>\w+)');
GO

-- Swap the subject of the sentence with the object of the sentence.
SELECT dbo.RegexReplace('The quick red fox jumped over the lazy brown dog', 
'^The (?<fox>(?:[\w]+\s){3})jumped over the (?<dog>(?:[\w]+\s){2}(?:[\w]+))$',

'The ${dog} jumped over the ${fox}');

The following Transact-SQL removes the assembly and functions from the database.

USE AdventureWorks
GO

IF OBJECT_ID(N'RegexMatches', N'FT') is not null
DROP Function RegexMatches;
GO

IF OBJECT_ID(N'Split', N'FT') is not null
DROP Function Split;
GO

IF OBJECT_ID(N'RegexReplace', N'FS') is not null
DROP Function RegexReplace;
GO

IF OBJECT_ID(N'Concatenate', N'AF') is not null
DROP Aggregate Concatenate;
GO

IF EXISTS (SELECT * FROM sys.assemblies WHERE [name] = 'StringUtils')
DROP ASSEMBLY StringUtils;

GO

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