Procedure for add or update SQL Server table and column description

AddOrUpdateTableAndColumnDescription

CREATE PROCEDURE dbo.PROC_AddOrUpdateTableAndColumnDescription 
    @fullName varchar(255),
   @description varchar(255)
AS
/*
Table exemple: <schema>.<table name> dbo.MyTable
Column Exemple: <schema>.<table name>.<column name> dbo.MyTable.Id
*/

/*Extrai o primeiro valor antes do ponto, representa o schema*/
declare  @schemaName varchar(255) = 
	(select top 1 trim(x.[value]) from string_split(@fullName, '.') x inner join sys.schemas s on s.[name]= x.[value]);
	declare @msg varchar(255);
if(@schemaName is null or @schemaName ='')
begin
	set @msg  =concat('The schema ',@schemaName, ' was found in ',db_name());
	THROW 90000, @msg, 1;  
end

/*Extrai o primeiro valor após o ponto, representa o nome da tabela*/
declare	@tableName varchar(255)=(select top 1 trim(x.[value]) as [value] 
		from string_split(@fullName, '.') x
		inner join sys.tables t on t.[name] = x.[value]
		where x.[value] <> @schemaName);

if(@tableName is null or @tableName ='')
begin
	set	  @msg  =concat('The table ',@tableName, ' was found in schema ', @schemaName, ' on database ',db_name());
	THROW 90001, @msg, 1;  
end
  
/*Verifica se existe 3 valores seprados por ponto (schema, tabela e coluna)*/
if (select count(*) from string_split(@fullName, '.')) =3
BEGIN
/*Extrai o valor da coluna*/
declare @columnName varchar(255) =(select top 1 trim(x.[value]) as [value] 
		from string_split(@fullName, '.') x
		inner join sys.all_columns c on c.[name] = x.[value] and c.object_id =object_id(concat(@schemaName,'.', @tableName))
		where x.[value] <> @schemaName and x.[value]<>@tableName);

		if(@tableName is null or @tableName ='')
		begin
			set	  @msg  =concat('The column ',@columnName,  ' on table ',@tableName, ' was found in schema ', @schemaName, ' on database ',db_name());
			THROW 90002, @msg, 1;  
		end

		/*Verifica se existe comentario para essa coluna e decide se precisa add ou atualizar*/
		if not exists(SELECT top 1  * FROM fn_listextendedproperty (NULL, 'schema',@schemaName, 'table',  @tableName,  N'COLUMN',  @columnName))
			exec sp_addextendedproperty N'MS_Description', @description, N'SCHEMA', @schemaName, N'TABLE', @tableName, N'COLUMN',  @columnName;
		else if 1=1
			exec sp_updateextendedproperty N'MS_Description', @description, N'SCHEMA', @schemaName, N'TABLE', @tableName, N'COLUMN',  @columnName;
END
else
	/*Entra nessa condição quando o texto enviado tem apenas schema e tabela*/
	/*Verifica se existe comentario para essa coluna e decide se precisa add ou atualizar*/
	if not exists(SELECT top 1  * FROM fn_listextendedproperty (NULL, 'schema',@schemaName, 'table',  @tableName, default, default))
		EXEC sys.sp_addextendedproperty @name=N'MS_Description', 
		@value=@description , @level0type=N'SCHEMA', @level0name=@schemaName, 
		@level1type=N'TABLE',@level1name=@tableName
	else
		EXEC sys.sp_updateextendedproperty 
			@name=N'MS_Description', @value=@description,
			@level0type=N'SCHEMA',	 @level0name=@schemaName, 
			@level1type=N'TABLE',    @level1name=@tableName