src/SQL/ColumnExpression.php
public function mid($column, int $start = 1, string $alias = null, int $length = 0): self
    {
        return $this->column((new Expression())->mid($column, $start, $length), $alias);
    }
public function mid($column, int $start = 1, string $alias = null, int $length = 0): self
    {
        return $this->column((new Expression())->mid($column, $start, $length), $alias);
    }
public function mid ( $ column , int $ start = 1 , string $ alias = null , int $ length = 0 ) : self { return $ this -> column ( ( new Expression ( ) ) -> mid ( $ column , $ start , $ length ) , $ alias ) ; }
Add a `MID` expression

@param   string|Expression $column Column
@param   int $start (optional) Substring start
@param   string $alias (optional) Alias
@param   int $length (optional) Substring length

@return  $this
Add a MID expression