I want to parameterize table_name:t_user_address_book(uid/500000).
for example: when uid = 1000, table_name = t_user_address_book0;
when uid = 500001, table_name = t_user_address_book1;
How to write?
public interface UserAddressBookMapper {
#Insert("insert into t_user_address_book? values(...)")
int upsert(Long uid, UserAddressBookMsg userAddressBookMsg);
}
You can choose the table with Mybatis XML code:
<choose>
<when test="uid gt 1000000">
<bind name="tableName" value="t_user_address_book2" />
</when>
<when test="uid gt 500000">
<bind name="tableName" value="t_user_address_book1" />
</when>
<otherwise>
<bind name="tableName" value="t_user_address_book0" />
</otherwise>
</choose>
Or you can compute the table name in the java and pass it as parameter.
Whatever your choice, the table name parameter in the query must be referenced with the $ notation instead of # since the value must replace the place holder as is to be part of the query and not being interpreted/bound/escaped as parameters are:
INSERT INTO ${tableName} ...
Despite use of XML, you can stick with annotations surrounding the query with <script> tags:
#Insert({"<script>",
"<choose> ...",
"INSERT ..."
"</script>"
})
Also when using Mapper interface with annotations, you need to name the parameters with there are more than 1:
#Insert("INSERT INTO table VALUES(#{uid}, #{userAddressBookMsg.propertyName1})")
int upsert(upsert(#Param("uid")Long uid, #Param("userAddressBookMsg") UserAddressBookMsg userAddressBookMsg);
However, it seems you want to split into multiple tables for volume issues, this is much complexity to handle while it would better be to keep a single table and look around on DB side about indexing and partitioning.
Quick response will be "no". It is not possible to give table name as parameter, because mybatis uses prepared statements.
I would suggest using table name as variable, and giving it to the statement string.
For example:
public interface UserAddressBookMapper {
static String tableName;
static void setTableName(String name) {
tableName = name;
}
#Insert({"insert into", tableName, "values(...)"})
int upsert(UserAddressBookMsg userAddressBookMsg);
You will have to set tableName before calling the method.
Related
I have multiple aggregate classes, such as Request, Scribe, Candidate, and Exam.
Sample schema:
Request (id, scribe_id, candidate_id, exam_id, status)
Scribe (id, name)
Candidate (id, name)
Exam (id, name, schedule)
As you can see, Request table has references to Scribe, Candidate, and Exam tables.
For one of the requirements, I need to return all requests based on a condition by including all the corresponding details of scribe, candidate, and exam.
For this, the query in my repository class will be similar to the following:
SELECT r.id, r.status, c.name, s.name,
e.schedule, e.name
FROM request r
JOIN candidate c ON r.candidate=c.id
JOIN scribe s ON r.scribe=s.id
JOIN exam e ON r.exam=e.id
WHERE <some-condition>
Now, is there a way to map the result of this query directly to a custom Java object and return the same in Spring Data JDBC?
I believe another alternative is to use the Spring JDBC template.
Curious, any out-of-the-box support from Spring Data JDBC?
Thanks.
I am able to return custom Java object by setting rowMapperClass value of org.springframework.data.jdbc.repository.query.Query annotation. For this need to define RowMapper for custom Java object.
Changes look similar to the following:
public class RequestResourceRowMapper implements RowMapper<RequestResource> {
#Override
public RequestResource mapRow(ResultSet resultSet, int rowNumber) throws SQLException { ... }
}
In repository class, need to set rowMapper value.
#Query(value = """
SELECT r.id, r.status, c.name, s.name,
e.schedule, e.name
FROM request r
JOIN candidate c ON r.candidate=c.id
JOIN scribe s ON r.scribe=s.id
JOIN exam e ON r.exam=e.id
WHERE <some-condition>
""",
rowMapperClass = RequestResourceRowMapper.class)
List<RequestResource> searchRequestResources(...);
This could have even been possible without using a custom row mapper as well, but in that case, you will have to assign different names to the columns across the tables. You could have defined a simple class and defined all the fields in there and for mapping the java fields with the corresponding columns in the table, you could have used the #Column attributes example:
public class RequestData {
#Column("id")
private Integer requestId;
#Column("scribe_id")
private String scribeId;
#Column("candidate_id")
private Integer candidateId;
#Column("scribe_name")
private String scribeName;
#Column("candidate_name")
private String candidateName;
#Column("exam_name")
private String examName;
#Column("exam_schedule")
private String examSchedule;
}
However, for such case, you need to have different column names across the schema's which might not be possible in your case as you have same column names in multiple schemas.
iBatis to MyBatis Migration:
Need Help for MyBatis foreach logic, because the Map contains Value as ArrayList.
The below java code is the logic:
employeeRequest.put("ID", employeeId);
Map <String,ArrayList<String> employeeRequest = new HashMap<String, ArrayList<String>>();
Set<String> employeeSet = new HashSet<String>();
for(Employee employee: employeeList) {
String name = employee.getName();
String value = employee.getValue();
if("EMPLOYEE".equalsIgnoreCase(name) {
employeeSet.add(value)
}
}
if(!employeeSet.isEmpty()) {
employeeRequest.put("EMPLOYEE", new ArrayList<String>(employeeSet))
}
iBatis SQL:
My Previous code I am using iBatis which has the following query
<select id="getEmployeeName" resultclass="java.util.HashMap" parameterClass="java.util.Map">
SELECT EMP.EMPNAM NAME FROM EMPLOYEE EMP
WHERE EMP.ID = #ID#
<isNotEmpty property="EMPLOYEE" prepend="AND">
<iterate property="EMPLOYEE" conjunction="AND">
EMP.EMPNAM != #EMPLOYEE[]#
<iterate>
</isNotEmpty>
</select>
MyBatis SQL:
Now I am migrating to MyBatis, so formatted the query as below
<select id="getEmployeeName" resultclass="java.util.HashMap" parameterClass="java.util.Map">
SELECT EMP.EMPNAM NAME FROM EMPLOYEE EMP
WHERE EMP.ID = #{ID}#
<if test="EMPLOYEE !=null and EMPLOYEE>0">
<foreach collection="EMPLOYEE" index="index" item="item" separator="AND">
EMP.EMP_ID != ${item}
</foreach>
</if>
</select>
Could any one of you please help me with the correct query for the above java code logic.
Missing spaces around separator value: AND instead of just AND.
For parameters use #{param} to bind parameter instead of ${param} that just concatenates values to the SQL string. That does not prevent from working but that is very bad.
!= is not standard SQL and will not work for every DB vendor (although it might do with the one you are using), unlike NOT column = value,
<foreach collection="EMPLOYEE" index="index" item="item" separator=" AND ">
NOT EMP.EMP_ID = #{item}
</foreach>
furthermore better use IN:
EMP.EMP_ID NOT IN (<foreach collection="EMPLOYEE" index="index" item="item" separator=", ">
#{item}
</foreach>)
I am unable to pass a composite key to a MyBatis <collection> element (using version 3.2.7). The MyBatis documentation states:
Note: To deal with composite keys, you can specify multiple column names to pass to the nested select statement by using the syntax column="{prop1=col1,prop2=col2}". This will cause prop1 and prop2 to be set against the parameter object for the target nested select statement.
However, all my attempts to implement this produce the Exception
org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.reflection.ReflectionException: Error instantiating class java.lang.Integer with invalid types () or values (). Cause: java.lang.NoSuchMethodException: java.lang.Integer.<init>()
The collection (which resides in another ResultsMap) is:
<collection property="foos" ofType="FooObject"
column="{param1=user_id,param2=foo_id}" select="getFoosByUser" >
<id property="userId" column="user_id" />
<id property="foo" column="foo_id" />
<result property="fooName" column="foo_name" />
</collection>
It should return an ArrayList of Foo objects. The composite key is user_id and foo_id. The select query is:
<select id="getFoosByUser" parameterType="Integer" resultType="FooObject">
SELECT
user_id AS userId,
foo_id AS fooId,
foo_name AS fooName
FROM foo_table
WHERE user_id = #{param1}
AND foo_id = #{param2}
</select>
The query works correctly if I only use one parameter, e.g. removed foo_id=#{param2} and then use column=user_id in the collection, but I cannot work out how to structure the column attribute correctly for two keys. Any ideas?
MyBatis is confused by using parameterType when there are more than one parameter. Modify you query mapping like this:
<select id="getFoosByUser" resultType="FooObject">
SELECT
user_id AS userId,
foo_id AS fooId,
foo_name AS fooName
FROM foo_table
WHERE user_id = #{param1}
AND foo_id = #{param2}
</select>
I need to convert String to Int32 value in my query. It must be done on sql server-side, not in memory.
I've seen answers how to do this in Model First approach, LINQ to Entities.
here and here
But I need it to be done with Code First.
I write query to DbSet<>.
Is there any way to do this? Please, help :)
New Answer:
The only way I can find information for is to use a custom query.
For instance:
from user in Users.SqlQuery("SELECT Id, CAST(Age AS INT) as Age, FirstName, LastName FROM Users")
select new
{
id = user.Id,
Age = user.Age
}
In my tests it seems every value for property on the entity you map to have to be included in the select even if you select to a custom object that do not include every property. In my example above I include FirstName and LastName even though they aren't used in the select.
Old answer:
About converting to string on sql-side:
You can use SqlFunctions.StringConvert if you cast your int to a double or decimal first
Problem with converting int to string in Linq to entities
from user in Users
select new
{
IdAsText = SqlClient.SqlFunctions.StringConvert((decimal)user.Id)
}
The cast to float or decimal is necessary because the STR-function on the sql-server requires a float: Why is there no int overload for SqlFunctions.StringConvert
Update:
In LINQPad the generated SQL-query from the above comes out to:
SELECT
[Extent1].[Id] AS [Id],
STR( CAST( [Extent1].[Id] AS decimal(19,0))) AS [C1]
FROM [dbo].[Users] AS [Extent1]
I am using myBatis and trying create a db entry for the class User.
How can i map the different field names to the column names?
Do i need to or should myBatis know of them?
My User class looks like this:
public class User {
private String username;
private String email;
...
and the column names are:
user_name
e_mail
The myBatis create method looks like this:
void createUser(User user)
... i've tried like this:
<insert id="createUser" parameterType="...User">
INSERT INTO users (user_name, e_mail) VALUE
(#{username},#{email})
</insert>
and this:
<insert id="createUser" parameterType="...User">
INSERT INTO users (user_name, e_mail) VALUE
(#{user.username},#{user.email})
</insert>
I keep getting:
Parameter 'username' not found. Available parameters are [1, 0, param1, param2]
respectively Parameter 'user'
Found the answer:
The code should look like this:
void createUser(#Param("user")User user)
<insert id="createUser" parameterType="...User">
INSERT INTO users (user_name, e_mail) VALUE
(#{user.username},#{user.email})
</insert>
You shouldn't have to specify the #param annotation if you have getters/setters for those private variables. You don't indicate in your code snippet that you do. MyBatis should be smart enough to call the getter on the variables assuming you have one. If you look at the docs here http://mybatis.github.com/mybatis-3/sqlmap-xml.html#Parameters they have an example just like what you're doing above (note your first insert mapping is the correct one).
<insert id="insertUser" parameterType="User" >
insert into users (id, username, password)
values (#{id}, #{username}, #{password})
</insert>