MySQL tutorial proofreading set problem

This article mainly introduces you to the proofreading set problem in mysql. I hope it will be helpful to friends in need!

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Proofreading set problem

Proofreading set is actually a way of comparing data.

There are three types of proofreading sets, namely:

• _bin: binary, binary comparison, case-sensitive;

• _cs：case sensitive, case sensitive, case sensitive;

• _ci：case insensitive, case insensitive, not case sensitive.

View (all) proofreading sets–> Basic syntax: show collation;

##As shown above As shown, MySQL database supports more than one hundred collation sets.

Next, let’s take a look at the application of the proofing set, because the proofing set will only take effect when the data is compared. Here, we use two proofreading sets of

utf8_bin and _ci for comparison:

-- 创建两张使用不同校对集的表create table my_collate_bin(
    name char(MySQL tutorial proofreading set problem)
)charset utf8 collate utf8_bin;create table my_collate_ci(
    name char(MySQL tutorial proofreading set problem)
)charset utf8 collate utf8_general_ci;

As shown in the figure above, we created two tables, namely

my_collate_bin and my_collate_ci, and their proofing sets are _bin and _ci## respectively. #. Then, add data to these two tables respectively: <pre class='brush:php;toolbar:false;'>-- 向表中添加数据insert into my_collate_bin values (&amp;#39;a&amp;#39;),(&amp;#39;A&amp;#39;),(&amp;#39;B&amp;#39;),(&amp;#39;b&amp;#39;);insert into my_collate_ci values (&amp;#39;a&amp;#39;),(&amp;#39;A&amp;#39;),(&amp;#39;B&amp;#39;),(&amp;#39;b&amp;#39;);</pre> Then view the data in the two tables respectively:

-- 查看表中的数据select * from my_collate_bin;select * from my_collate_ci;

Next, we will use the To sort by a certain field (both

my_collate_bin

and my_collate_ci have only one field), the basic syntax is: <pre class='brush:php;toolbar:false;'>order by + 字段名 + [asc/desc];</pre>where,

asc

means ascending order, desc means descending order, and the default is ascending order. Execute the following SQL statement: <pre class='brush:php;toolbar:false;'>-- 排序比较select * from my_collate_bin order by name;select * from my_collate_ci order by name;</pre>

As shown in the picture above, obviously the proofreading set is effective!

In addition, we need to pay special attention to the following:

The proofing set must be declared before there is no data. If the proofing set is modified after there is data, the modification will be invalid.

Warm reminder:

The content enclosed by the symbols [] represents optional options; the symbols represent the meaning of connection

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