Does Mysql have an equivalent to @@ROWCOUNT like in mssql?

The simplest way would be to use a variable:

mysql> SELECT @rowcount:=COUNT(*) FROM my_table;
mysql> SELECT @rowcount;

Or you can use FOUND_ROWS() construct after putting a SQL_CALC_FOUND_ROWS in a SELECT statement.

mysql> SELECT SQL_CALC_FOUND_ROWS * FROM my_table;
mysql> SELECT FOUND_ROWS();

For SELECTs you can use the FOUND_ROWS construct (documented here):

SELECT SQL_CALC_FOUND_ROWS something FROM your_table WHERE whatever;
SELECT FOUND_ROWS( ) ;

which will return the number of rows in the last SELECT query (or if the first query has a LIMIT clause, it returns the number of rows there would've been without the LIMIT).

For UPDATE/DELETE/INSERT, it's the ROW_COUNT construct

INSERT INTO your_table VALUES (1,2,3);
SELECT ROW_COUNT();

which will return the number of affected rows.

mysql> SELECT SQL_CALC_FOUND_ROWS * FROM tbl_name

    -> WHERE id > 100 LIMIT 10;

mysql> SELECT FOUND_ROWS();

Read more about this here