Stored procedure to Create external table for delta format error Incorrect syntax near ')'

Question

This stored procedure is to create delta external tables in Azure Synapse serverless database.

The environment is Azure Synapse OnDemand server (serverless database).

CREATE OR ALTER PROCEDURE sp_copy_delta_to_table
    (@table_name NVARCHAR(100),
     @delta_file_url NVARCHAR(1000))
AS
BEGIN
    IF LEN(@delta_file_url) = 0
    BEGIN
        RAISERROR('Delta file URL parameter cannot be empty', 16, 1)
        RETURN
    END

    DECLARE @external_table_name NVARCHAR(100) = @table_name + '_external';

    -- Build the CREATE EXTERNAL TABLE statement dynamically
    DECLARE @sql NVARCHAR(MAX) = N'CREATE EXTERNAL TABLE ' + @external_table_name + ' '

    SELECT @sql += QUOTENAME(COLUMN_NAME) + ' ' + DATA_TYPE +
        CASE 
            WHEN CHARACTER_MAXIMUM_LENGTH IS NOT NULL THEN '(' + CAST(CHARACTER_MAXIMUM_LENGTH AS VARCHAR(10)) + ')'
            ELSE ''
        END +
        ', ' -- Add a space character after the comma
    FROM INFORMATION_SCHEMA.COLUMNS 
    WHERE TABLE_NAME = @table_name 
    ORDER BY ORDINAL_POSITION

    SET @sql = LEFT(@sql, LEN(@sql) - 1) + ' WITH (LOCATION = ''' + @delta_file_url + ''', DATA_SOURCE = datasource_bronzedb001, FILE_FORMAT = DELTA)'

    --PRINT @sql -- Add this line to print the CREATE EXTERNAL TABLE statement before executing it
    -- Execute the CREATE EXTERNAL TABLE statement
    EXEC (@sql)

    -- Insert the data from the Delta file into the final table
    SET @sql = 'INSERT INTO ' + @table_name + ' SELECT * FROM ' + @external_table_name + ''
    EXEC (@sql)
END

I'm calling it like this:

EXEC sp_copy_delta_to_table 'ABC_Test', 'abfss://hhrrn@XXXXXX.dfs.core.windows.net/bronze/ext/ABC_Test';

I get this error:

Started executing query at Line 5
"Incorrect syntax near ')'."