Mybatis wildcard, Mybatis and SQL fuzzy query

A, mybatis of $ and #

In mybatis in $and #are dynamic parameters passed in the sql.
select id,name,age from student where name=#{name}
This name is dynamic and variable. When you pass what value will be executed sql statement based on your passed-in value.

1. MyBatis SQL statements used to pass parameters parameterType, the type can be substantially parameterType type int, String, HashMap and custom types java
2. In the xml to write SQL are used #, such as #{param}.
   But sometimes you see with $time, such as${param}
3. Well $and #, what difference does it make?
   (1) wildcard character " #" is passed as a string value, such as:
   select id,name,age from user where id=#{id}
当前端把id值1，传入到后台的时候，就相当于 (#{} 传入值时，sql解析时，参数是带引号的)
select id,name,age from student where id ='1'
   (2) wildcard character " $" is displayed directly incoming data generation sql statement, such as
   select id, name, age from user where id=${id}
当前端把id值1，传入到后台的时候，就相当于 (${}穿入值，sql解析时，参数是不带引号的)
select id,name,age from student where id = 1
   (3) " #" can be largely prevent sql injection. (Splicing statement)
   #{}: resolved to a JDBC prepared statement (prepared statement) parameter markers, a # {} is interpreted as a parameter placeholder.
   ${}: Just a pure replacement for the broken string, in a dynamic SQL parsing stage will be variable substitution. For example:
   select id,name,age from student where name=#{name} -- name='cy'
select id,name,age from student where name=${name} -- name=cy
   (4) However, if used in the order by the need to use " $."
   (5) is often used in most cases " #", but must be used under different circumstances " $."

Two, Mybatis various fuzzy query

1. sql string splicing

SELECT * FROM tableName WHERE name LIKE CONCAT(CONCAT('%', #{text}), '%');

2. Instead of using $ {...} # {...}

SELECT * FROM tableName WHERE name LIKE '%${text}%';

3. stitching program

 Java

  // or String searchText = "%" + text + "%";

   String searchText = new StringBuilder("%").append(text).append("%").toString();

   parameterMap.put("text", searchText);

SqlMap.xml

   SELECT * FROM tableName WHERE name LIKE #{text};

4. Match case inquiry

   SELECT *  FROM TABLENAME  WHERE UPPER(SUBSYSTEM) LIKE '%' || UPPER('jz') || '%'
    --或者是
   SELECT *   FROM TABLENAME  WHERE LOWER(SUBSYSTEM) LIKE '%' || LOWER('jz') || '%'

Three, MySql fuzzy query

During a database query, a complete query and fuzzy query points.
General fuzzy query as follows:
SELECT 字段 FROM 表 WHERE 某字段 Like 条件

Wherein on condition, SQL is provided four kinds of pattern matching :
(1) %: 0 indicates an arbitrary or more characters . Can match any type and length of characters, in some cases if the Chinese use two percent signs (%%) denote.
For example, SELECT * FROM [user] WHERE u_name LIKE '%三%'
will the u_name as "Joe Smith", "Zhang cat three", "three legs", "Zang" and so on "three" to find out the whole record.
In addition, if you need to find out u_name in both "three" and a "cat" record, conditions of use and
SELECT * FROM [user] WHERE u_name LIKE '%三%' AND u_name LIKE '%猫%'
if used SELECT * FROM [user] WHERE u_name LIKE '%三%猫%'
although able to search out the "three legs", but you can not search out qualified "Zhang cat three."

(2) _: represents any single character . Matches any single character, it is used to limit the expression of the character length statement:
example SELECT * FROM [user] WHERE u_name LIKE '_三_'
only identify the "Zang" u_name such as words of a word and the "three";
Another example SELECT * FROM [user] WHERE u_name LIKE '三__';
only find the "three legs" so name for the first word and the words "three" in;

(3) []: The character listed in the brackets in a (similar to regular expressions) . Specify a character string or the scope of the claims to be matched to any one of them.
For example, SELECT * FROM [user] WHERE u_name LIKE '[张李王]三'
you will find "Joe Smith", "Lee III", "King III" (rather than "Zhang Li Wang Three");

If there is a series of characters [] within (01234, abcde and the like) can be abbreviated as "0-4", "ae"
the SELECT * the FROM [the User] the WHERE u_name the LIKE 'old [1-9]'
will identify " old one "," the old 2 ", ......" old 9 ";

(4) [^]: represents a single character is not listed in the brackets . Its value, and [] the same, but it requires a character to any object other than the specified character matches.
For example, SELECT * FROM [user] WHERE u_name LIKE '[^张李王]三'
will find no name, "Zhang", "Li", "King" and "Zhao Three", "Sun Three" and so on;
SELECT * FROM [user] WHERE u_name LIKE '老[^1-4]';
the exclusion of "the old one" to "the old 4", looking for "old 5" and "old 6 "......

Note:
Due to the wildcard's sake, lead us to query the special character "%", "_", "[" the statement can not be achieved properly, and the special characters "[]" from the enclosed can be a normal query. Accordingly, we write the following function:

function sqlencode(str)
str=replace(str,"[","[[]") '此句一定要在最前
str=replace(str,"_","[_]")
str=replace(str,"%","[%]")
sqlencode=str
end function

Will be examined before the query string before the function can be treated, use of such a database query and is connected on the page is to be noted Hou:
As Select * FROM user Where name LIKE '老[^1-4]';
above 'old [^ 1-4] 'is to have a single quotes ,do not forget!

SQL模糊查询，使用like比较关键字，加上SQL里的通配符，请参考以下： 
1、LIKE'Mc%' 将搜索以字母 Mc 开头的所有字符串（如 McBadden）。 
2、LIKE'%inger' 将搜索以字母 inger 结尾的所有字符串（如 Ringer、Stringer）。 
3、LIKE'%en%' 将搜索在任何位置包含字母 en 的所有字符串（如 Bennet、Green、McBadden）。 
4、LIKE'_heryl' 将搜索以字母 heryl 结尾的所有六个字母的名称（如 Cheryl、Sheryl）。 
5、LIKE'[CK]ars[eo]n' 将搜索下列字符串：Carsen、Karsen、Carson 和 Karson（如 Carson）。 
6、LIKE'[M-Z]inger' 将搜索以字符串 inger 结尾、以从 M 到 Z 的任何单个字母开头的所有名称（如 Ringer）。 
7、LIKE'M[^c]%' 将搜索以字母 M 开头，并且第二个字母不是 c 的所有名称（如MacFeather）。 

for example:

sql = "select * from zipcode where (address like'%" & zipcode_key & "%') or (city like'%" & zipcode_key & "%') or (province like'%" & zipcode_key & "%') order by province,city,address

Examples explain : zipcode_key queries based on zip code table in the variable zipcode corresponding data sentence is determined whether the variable is non-digital zipcode_key query, with a string of arbitrary length to match%, from the table address, city, Shozo column query all the data items contained keywords and provincial, city, address sorting.

Examples of fuzzy query using stored procedures:

SELECT * FROM Questions where QTitle like ' % [ '+ @KeyWord +' ] % ' and IsFinish = @IsFinsih`

Statement pairs of square brackets is the key to writing format.