原文链接,  直接运行就会报错

by admin on 2019年10月18日

  
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mysql中替代null的IFNULL()与COALESCE()函数详解

  在MySQL中isnull()函数不能作为替代null值!

  如下:  mysql中替代null的IFNULL()与COALESCE()函数详解

  首先有个名字为business的表:

图片 1

  SELECT ISNULL(business_name,’no business_name’) AS bus_isnull
FROM business WHERE id=2

  直接运行就会报错:

  错误代码: 1582

  Incorrect parameter count in the call to native function ‘isnull’

  所以,isnull()函数在mysql中就行不通了。可以用ifnull()和coalesce()代替。如下:

  使用ifnull()函数:

  SELECT IFNULL(business_name,’no business_name’) AS bus_ifnull
FROM business WHERE id=2

  运行结果:

图片 2

  当查询的值不为null时:

  SELECT IFNULL(business_name,’no business_name’) AS bus_ifnull
FROM business WHERE id=1

  结果如下:

图片 3

  使用coalesce()函数:

  SELECT COALESCE(business_name,’no business_name’) AS bus_coalesce
FROM business WHERE id=2

  结果如下:

图片 4

  当查询值不为null时:

  SELECT COALESCE(business_name,’no business_name’) AS bus_coalesce
FROM business WHERE id=1

图片 5

  其中:coalesce()还可以返回第一个不为null的值。如下:

  SELECT COALESCE(business_name,district_id,id) AS bus_coalesce
FROM business WHERE id=2

图片 6

  那么,isnull()在mysql中怎么用呢?答案就是用在where后面。如下:

  SELECT * FROM business WHERE ISNULL(business_name)

  结果如下:

图片 7

  同样,is null 和is not null 也是用在where后面。

  SELECT * FROM business WHERE business_name IS NULL

  结果如下:

图片 8

  SELECT * FROM business WHERE business_name IS NOT NULL
  mysql中替代null的IFNULL()与COALESCE()函数详解

图片 9

在MySQL中isnull()函数不能作为替代null值! 如下:
mysql中替代null的IFNULL()与COALESCE()函数详解 首先有个…

原文链接:

 

By Robert Thibodeau – 

Starting a business can be a very daunting adventure if a proper plan is
not put in place. Most entrepreneurs start up their businesses without
putting adequate plans in place to succeed. No wonder one out of every
five businesses crumbles within 5 years! If one thing should be taken
very seriously, it should be your business plan. This is your “blueprint
for success.”

Every business begins from a thought. A thought or idea can only become
reality when expected actions are taken. When an idea is conceived, the
logical corollary is that such ideas need to be written out, in black
and white and on paper; or else the idea will fade off when the
enthusiasm that the thought initially brought subsides. Hence, having a
written business plan is pertinent if your business is to stand the test
of time.

Now, what is a Business Plan?

One definition, according to entrepreneur.com, is that a business plan
is a “written description of the future of your business; a document
that indicates what you intend to do and how you intend to do it.”
If
you notice a paragraph on the back of an envelope describing your
business strategy, you have already started a written plan, or at least
the first draft of a plan. The business plan itself consists of a
narrative and several financial worksheets.

The very act of planning helps you to think things through in a
systematic and thorough way. Study and research your market niche if you
are not sure of the facts, and look at your ideas critically. It may
take some time now, but helps to avert costly and disastrous mistakes in
future.

In this article, I want to provide a very brief look at the steps
involved in planning a business:

  1. Identify Your Passion: Knowing what you love doing, even without
    making money, is the stepping stone in starting any business. Most
    people enter into a business they know nothing about, and stop after
    only few months. Some get tired of their businesses simply because they
    are not happy with the activities involved in running the business
    anymore. According to Sabrina Parsons, (CEO of Palo Alto Software)
    “Know yourself, and work in a job that caters to your strengths. This
    knowledge will make you happier.”

The reason why many businesses fail in their first five years is because
the entrepreneurs do not find fulfillment in running their business
anymore. Hence, they tend to move on in search for happiness.

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