PHP

laravel migration table bigint

$this->bigIncrements('id');
This takes care of making it unsigned, auto increment and primary key

laravel migration smallint length

For Laravel & Mysql

String types
CHAR - 1 to 191 (trailing spaces removed)
STRING - 1 to 16,300 (user defined)
TEXT - 1 to 65,535
MEDIUMTEXT - 1 to 16,777,215
LONGTEXT - 1 to 4,294,967,295

Integer types
TINYINT - 0 to 255 (unsigned) | -128 to 127 (signed)
SMALLINT - 0 to 65,535 (unsigned) | -32,768 to 32,767 (signed)
MEDIUMINT - 0 to 16,777,215 (unsigned) | -8,388,608 to 8,388,607 (signed)
INT - 0 to 4,294,967,295 (unsigned) | -2,147,483,648 to 2,147,483,647 (signed)
BIGINT - 0 to 18,446,744,073,709,551,615 (unsigned) | -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 (signed)

Floating types
Structure: `([max decimal places], [max precision])`
FLOAT - ([0-7], [0-23])
DOUBLE - ([0-14], [24-53])
DECIMAL - ([0-65], [0-30])