Think/Model.php
public function where(array $where = [])
    {
        if (isset($this->options['where'])) {
            $this->options['where'] = array_merge($this->options['where'], $where);
        } else {
            $this->options['where'] = $where;
        }

        return $this;
    }
public function where(array $where = [])
    {
        if (isset($this->options['where'])) {
            $this->options['where'] = array_merge($this->options['where'], $where);
        } else {
            $this->options['where'] = $where;
        }

        return $this;
    }
指定查询条件 支持安全过滤
@param array $where 条件表达式

@return $this