MySQL Dynamic Table issue - mysql

Question

Every month we get a CSV file that contains 300+ columns. The layout of the file can change whenever, and columns can be added/removed. I'm in need of a way to create a dynamic table that contains the exact number of columns needed. I don't care about column names, they can be Column1, Column2, etc.. and I plan to set all types to Varchar(500).
Ideally what I would I want to accomplish is a stored procedure that I can simply pass in the number of columns needed and it will loop to create the necessary Table Definition sql and then execute that sql.
Is accomplishing this even possible? I had started to write the following:
BEGIN
Declare loopvar int default 1;
Declare tsql VarChar(5000);
Declare table_definition VarChar(8000);
Declare tablename varchar(20);
Set table_definition = 'Column';
set tablename = 'npi_data';
Set loopvar = 1;
While loopVar < 362 DO
set tsql = table_definition + loopvar + 'varchar(500) DEFAULT NULL' ;
set loopvar = loopvar + 1;
end while;
set tsql = 'CREATE TABLE' + tablename + '(' + tsql + ') ENGINE=InnoDB DEFAULT CHARSET=utf8';
execute tsql;
END;
I'd like something close to that but all I really need is the ability to create a table with any given number of columns.
Thanks!

Answer 1

If you mean you want to be able to pass a list of column names, like 'A,B,C', and use it to generate a list of column definitions, like A varchar(500) DEFAULT NULL,B varchar(500) DEFAULT NULL,C varchar(500) DEFAULT NULL and, eventually, a CREATE TABLE statement with that definition list, you could use an approach like this:
...
SET columnnames = 'A,B,C';
SET sql = CONCAT(
REPLACE(columnnames, ',', ' varchar(500) DEFAULT NULL,'),
' varchar(500) DEFAULT NULL'
);
SET sql = CONCAT('CREATE TABLE ', tablename, ' (', sql, ')');
...
That is, every comma in the name list is expanded so as to complete the definition of the column preceding the comma. As the last item isn't followed by a comma, the type is simply concatenated one more time to the result of REPLACE.
Alternatively, to avoid the repetition of the varchar(500) DEFAULT NULL bit, you could do this:
...
SET columnnames = 'A,B,C';
SET sql = REPLACE(CONCAT(columnnames, ','), ',', ' varchar(500) DEFAULT NULL,');
SET sql = LEFT(sql, LENGTH(sql) - 1);
SET sql = CONCAT('CREATE TABLE ', tablename, ' (', sql, ')');
...
In this case, a comma is added after the last name, then all commas in the resulting string are replaced like in the previous examples. As a final touch to the list, the trailing comma is removed and finally the complete statement is built.
Either way, no loop is needed.