Snippet Name: HTML_Entity_Decoder_Function

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Created Date: 2025-06-16 13:12:40
Last Modified Date: 2025-05-31 10:32:16

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DBA Notes:

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Title: HTML Entity Decoder Function
Author: user
in SQL Server 2019 , can you help me build a function that converts all htmp entities like "'" to their ascii equivalent

Author: ChatGPT
Absolutely! Here???s a SQL Server 2019 scalar function that will help you convert common **HTML entities** (like `'`, `&`, `<`, `>`, `"`, etc.) into their **ASCII equivalents**.  

We will use `REPLACE()` calls inside the function, as T-SQL does not have built-in HTML decoding like some programming languages.

Here???s the function:

```sql
CREATE FUNCTION dbo.fn_HtmlDecode (@input NVARCHAR(MAX))
RETURNS NVARCHAR(MAX)
AS
BEGIN
    -- Replace common HTML entities with their ASCII equivalents
    SET @input = REPLACE(@input, ''', '''')
    SET @input = REPLACE(@input, '"', '"')
    SET @input = REPLACE(@input, '>', '>')
    SET @input = REPLACE(@input, '<', '<')
    SET @input = REPLACE(@input, '&', '&')
    SET @input = REPLACE(@input, ''', '''')  -- numeric code for apostrophe
    SET @input = REPLACE(@input, '"', '"')  -- numeric code for quote

    -- You can add more replacements as needed

    RETURN @input
END
GO
```

### Example usage

```sql
SELECT dbo.fn_HtmlDecode('This "book" costs '10' dollars & is great.')
```

Expected result:
```
This "book" costs '10' dollars & is great.
```

---

### Notes:
??? You can extend this function by adding more entities if needed (just follow the same `REPLACE` pattern).  
??? This covers the **most common entities** that appear in HTML.  
??? This function is lightweight and easy to apply in queries or views.

If you want, let me know and I can also help write:
- A **table-valued function** for batch processing rows  
- A **CLR function** (if you want full HTML decoding like in .NET)  
- Or an **inline query** example using this function.

Would you like me to include more entities or write those other options? Let me know!

Author: user
i need to convert all elements, not just common ones

Author: ChatGPT
Great ??? thanks for clarifying!  

SQL Server by itself **doesn???t have a built-in function to decode *all* HTML entities** like `€`, `©`, or `😀`. But you have two possible approaches:

---

### ???? **Option 1: Expand the REPLACE list**
  
You can **expand the T-SQL function** to include more named and numeric entities by manually adding them to the `REPLACE()` chain.  
For example:

```sql
SET @input = REPLACE(@input, '€', '???')
SET @input = REPLACE(@input, '©', '??')
SET @input = REPLACE(@input, '©', '??')
SET @input = REPLACE(@input, '😀', '????') -- grinning face emoji
```

This works, but it becomes **huge and hard to maintain** as the list of HTML entities is long (~2500+).

---

### ???? **Option 2: Use SQL CLR with .NET**

A **much better solution** is to create a SQL CLR function and use the .NET **`System.Web.HttpUtility.HtmlDecode()`** method, which can decode **all known HTML entities automatically**.

Here???s how you can do that.

---

### ??? Example: SQL CLR function to decode all HTML entities

1?????? **Enable CLR integration**

```sql
EXEC sp_configure 'clr enabled', 1;
RECONFIGURE;
```

---

2?????? **Create a .NET assembly**

You will need to compile this simple C# code as a DLL:

```csharp
using System;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
using System.Web;

public class HtmlDecoder
{
    [SqlFunction]
    public static SqlString HtmlDecode(SqlString input)
    {
        if (input.IsNull)
            return SqlString.Null;

        return new SqlString(HttpUtility.HtmlDecode(input.Value));
    }
}
```

---

3?????? **Deploy the assembly to SQL Server**

Example:

```sql
CREATE ASSEMBLY HtmlDecodeAssembly
FROM 'C:\Path\To\HtmlDecode.dll'
WITH PERMISSION_SET = SAFE;
GO
```

---

4?????? **Create the SQL function**

```sql
CREATE FUNCTION dbo.fn_HtmlDecode (@input NVARCHAR(MAX))
RETURNS NVARCHAR(MAX)
AS EXTERNAL NAME HtmlDecodeAssembly.[HtmlDecoder].[HtmlDecode];
GO
```

---

5?????? **Use it in your queries**

```sql
SELECT dbo.fn_HtmlDecode('Tom & Jerry € <tag> ©')
```

Expected result:
```
Tom & Jerry ??? <tag> ??
```

---

### ???? Summary of options

| Option             | Pros                                | Cons                                    |
|--------------------|-------------------------------------|----------------------------------------|
| Expand REPLACE    | Simple, stays inside T-SQL          | Only handles the entities you manually add |
| SQL CLR + .NET    | Handles all entities automatically | Needs .NET assembly, CLR enabled, deploy step |

---

### ???? Bonus: Want me to prepare:
??? The full `.cs` file  
??? A ready-to-use DLL for deployment  
??? A T-SQL deployment script  

If yes, just say **???Yes, prepare the CLR package???** ??? I???ll build it out for you! ????