What does the prepend and specific meaning of Ibatis

If the parentid is not null or an empty string, then prepend is added before the parentid = parentid you executed, i.e. and parentid = parentid

But if your is written in and contains prepend, then the first isnotempty prepend is ignored.

For example, change the example you gave.

select * from menu

parentid = #parentid#

newparentid= #newparentid#

Then the second prepend="and"It will be preceded by newparentid= newparentid.

select * from menu !!where!!!and!!!The first one ignores) parentid = parentid

and!!!newparentid= #newparentid#

In between is the content of prepend.

isequal is equivalent to the equal method in string, property specifies the name of the comparison property, comparevalue indicates the parameter to be compared, and prepend indicates the comparison condition.

1.The previous parameterclass is no longer available in mybatis, and the parametertype should be used in mybatis. In addition, the resultmap can no longer be used, and it has been changed to type

tag can't be used, the following configuration is wrong in mybatis[html] view plaincopy= fparentid

like #logintopimage#

#fid#like #fname#

like #loginmiddleimage#like #versionnumber#

like #majortitle#

like #logintitle#

like #majormiddleimage#like #loginbottomimage#like #majortopimage#

like #logo#

like #address#

like #fax#

like #phone#

like #zip#

like #email#

not in ($containids$)

Mybatis and ibatis are both persistence layers and ORM layers, and mybatis is an upgraded version of iBatas.

1. The difference between configuration files, ibatis needs the DAO implementation layer, while mybatis can omit this layer, and it is OK to remove it directly according to the ID in the DAO layer

The following examples hope you find helpful.

select * from accountid = #id#

name like '%name$%'

When id and name are not null, the generated SQL statement is:

select * from account where (id=id value) and name like'%name of the value'

The prefix where is not added when the sum clause is not

The prepend attribute of sum will only be added when the parallel clause exists, because there is silence.

Recognize the property: removefirstprepend="true"

The open and close attributes are included with dynamic statements.

select * from accountid = #id#

name like '%name$%'

When id and name are not null, the generated SQL statement is:

select * from account where (id=id value) and name like'%name of the value'

The prefix where is not added when the and laughing vertical clauses are not

The prepend attribute of hail is added only when a parallel clause exists, because there is silence.

Recognize the property: removefirstprepend="true"

The open and close attributes are included with dynamic statements.

element to divide the dynamic part of the SQL statement. The dynamic section can contain as many conditional label elements as it wants, and the conditional label determines whether to include the sql** in the statement. All conditional tag elements will work according to the parameter object passed to the dynamic query statement.

Both elements and conditional elements have a "prepend" attribute, which is part of dynamic sql and can be overridden by the "prepend" attribute of the parent element if necessary. In the example above, the prepend attribute "where" will override the first conditional element that is "true". This is necessary to ensure that the correct SQL statements are generated.

For example, in the first conditional element that is "true", "and" is not needed, and in fact, adding it is bound to be wrong. The following subsections discuss different conditional elements, including binary conditional elements, unary conditional elements, and other dynamic elements.

tag, that is, if any condition in the middle part of the tag is true, one will be added to the current SQL statement"where"characters.

If there is only one judgment condition, you can directly use :

name like '%name$%'

Fuzzy query: In general, the parameters of ibatis use the form param in sqlmap, and the parameter name is wrapped in ', but when using fuzzy query, you must change to $Ibid.

When setting up the buried range query, you must use double judgment, such as:

#_starttime#

and createtime < endtime.

There's an easy way to encapsulate the arguments to name= when they're passed in"%name%"such a string, and then directly name like name when using it

Of course, you can also write %$factory code$%$ is that the value wrapped in it is the real original value, not the string object. For example, if you don't use $$, it may be'name', using $$ is the name

But I think you're wrong here.

like '%$used_type$%'

The first dynamic statement followed by where does not require the and keyword.