"super-dynamic" query with MyBatis - java

Is there way to create sql query on the fly with MyBatis? To concretize: I have a query, where part of it (but not parameter) needs to be created in the runtime:
with dummy (id) as (
values (#{rangeEnd}) union all
select id - 1 from dummy where id - 1 >= #{rangeStart}
).......
The second part can be used as parameter, but, when trying the query as it is I get an exception:
[SQL0584] NULL or parameter marker in VALUES not allowed.
With plain JDBC I use MessageFormat:
PreparedStatement ps = connection.prepareStatement(
MessageFormat.format(MY_QUERY, currentRange.getRangeEnd()))
, but I haven't found a way how to do it with MyBatis.

It's really easy (answer from Dynamic Select SQL statements with MyBatis):
with dummy (id) as (
values (${rangeEnd}) union all
select id - 1 from dummy where id - 1 >= #{rangeStart}
).......

Use #SelectProvider annotation:
public interface SqlMapper {
static class PureSqlProvider {
public String sql(String sql) {
// Create your query here
return sql;
}
}
#SelectProvider(type = PureSqlProvider.class, method = "sql")
public List<Dummy> select(String sql);
}

Related

Create table as select with parameter using jdbcTemplate

I want to use jdbcTemplate to create table based on another table under condition. I have postgres database. When I execute this and pass parameter:
String SQL = "create table test as (select * from users where countryId =?)";
jdbcTemplate.update(SQL, new Object[] {3})
I receive table test with all columns from users table but with no rows.
However, when I execute this:
String SQL = "create table test as (select * from users where countryId =3)";
jdbcTemplate.update(SQL)
I receive test table with rows where countryId = 3, so that is what I was expecting to receive in the first solution.
Your passing of the bind variable is not correct, but it does not play any role.
You simple can not use a bind variable in a data definition statement as you immediately see in the triggered error
Caught: org.springframework.jdbc.UncategorizedSQLException:
PreparedStatementCallback; uncategorized SQLException for SQL
[create table test as (select * from users where countryId =?)];
SQL state [72000]; error code [1027];
ORA-01027: bind variables not allowed for data definition operations
So you have two options, either concatenate the statement (which is not recommended due to the danger of SQL injection)
or split the statement in two parts:
// create empty table
sql = "create table test as (select * from users where 1 = 0)";
jdbcTemplate.update(sql)
// insert data
sql = "insert into test(countryId, name) select countryId, name from users where countryId =?";
updCnt = jdbcTemplate.update(sql, new SqlParameterValue(Types.INTEGER,3));
Note that in the insert statement you can see the correct way of passing an interger value of 3 as a bind variable.
You can follow below approach as well:-
jdbcTemplate.execute("CREATE TABLE IF NOT EXISTS employee_tmp (id INT NOT NULL)");
List<Object[]> employeeIds = new ArrayList<>();
for (Integer id : ids) {
employeeIds.add(new Object[] { id });
}
jdbcTemplate.batchUpdate("INSERT INTO employee_tmp VALUES(?)", employeeIds);
Here you may query with 2 operations to avoid SQL injection.
You are using method update from jdbcTemplate in a wrong way.
Try with this:
String SQL = "create table test as (select * from users where countryId = ?)";
jdbcTemplate.update(SQL, 3);

Spring JDBC Template - Oracle DB Function returns null

I have my Oracle DB Stored Function as below:
CREATE OR REPLACE FUNCTION FN_EMP_CNT (EMP_ID NUMBER) RETURN NUMBER
IS
OLD_COUNT NUMBER(5) DEFAULT 0;
NEW_COUNT NUMBER(5) DEFAULT 0;
BEGIN
SELECT
COUNT(EMP_ID) INTO OLD_COUNT
FROM
OLD_DEPT
WHERE
EID = EMP_ID
AND DEPT_STAT='Closed';
SELECT
COUNT(EMP_ID) INTO NEW_COUNT
FROM
NEW_DEPT
WHERE
EID = EMP_ID
AND DEPT_STAT='Closed'
RETURN (NEW_COUNT + OLD_COUNT);
END;
When I use the below sql query directly it returns the correct number as 2:
SELECT FN_EMP_CNT(123) FROM DUAL;
But when I use Spring JDBC Template for retrieving the data it returns null.
int noOfEmps = jdbcTemplate.queryForObject("SELECT FN_EMP_CNT(?) FROM DUAL", new Object[] { empID}, Integer.class);
The most probable cause is that you use a wrong order of parameters, see Javadoc queryForObject
queryForObject(java.lang.String sql, java.lang.Class<T> requiredType, java.lang.Object... args)
Query given SQL to create a prepared statement from SQL and a list of
arguments to bind to the query, expecting a result object.
So use first the required return type followed by the parameter
This works for my fine
sql = 'SELECT FN_EMP_CNT(?) FROM DUAL'
res = jdbcTemplate.queryForObject(sql, Integer.class, 4)
HTH

Java native SQL query to display all values when an input param is null

I have the following DAO method:
public String getSomeTable(final String param1) {
String sqlString = "select * from table where name ilike ?";
Query query = this.getEntityManager().createNativeQuery(sqlString);
query.setParameter(1, "%param1%");
}
If param1 is null or empty then I want to select all entries from the table. What is the correct way to do this? I am currently using the following:
public String getSomeTable(final String param1) {
String sqlString = "select * from table where name = ?";
Query query = this.getEntityManager().createNativeQuery(sqlString);
if(param1 == null)
query.setParameter(1, "%%");
else
query.setParameter(1, "%param1%");
}
But this is not scalable. I have datatypes like integer, date, etc. I want to know if there is a way to skip checking for that parameter if it is null.
I was planning to use COALESCE(?, CASE WHEN ? = '' THEN '%%' ELSE '%?%') but I think ? can be used only once for a particular parameter. The next one > I write is linked to second param.
On SQL Server, I use something like this, perhaps you can translate it to postgres:
DECLARE #variable INT = NULL;
SELECT *
FROM sysobjects
WHERE
(1 = CASE WHEN #variable IS NULL THEN 1 ELSE 2 END)
OR
(id LIKE #variable);

select scope_identity() using createSQLQuery in Hibernate

I am forced to use createSQLQuery to insert values into tables with an Identity column (the first column and the primary key) using hibernate. Using hibernate classes are not an option since the tables are created on the fly for each customer that is added to the system. I have run the query and it successfully inserts into the table. I then execute a "select scope_identity()" and it always returns null. "select ##Identity" works but that is not guaranteed to be the correct one. I have also tried to append "select scope_identity()" to the insert query. Then I tried query.list() and query.uniqueResult() both of which throw the hibernate exception of "No Results ..."
Session session = DatabaseEngine.getSessionFactory().openSession();
String queryString = "insert into table1 (dataid) values (1)"
SQLQuery query = session.createSQLQuery(insertQueryString);
query.executeUpdate();
query = session.createSQLQuery("select scope_identity()");
BigDecimal entryID = (BigDecimal)query.uniqueResult();
The simple example table is defined as follows:
"CREATE TABLE table1 (EntryID int identity(1,1) NOT NULL," +
"DataID int default 0 NOT NULL, " +
"PRIMARY KEY (EntryID))";
Is there a way I am missing to use scope_identity() with createSQLQuery?
Actually the SQLServerDialect class used by Hibernate uses the same "scope_identity()" too.
The reason why it's not working is because you need to execute those in the same statement or stored procedure.
If you execute the scope_identity() call in a separate statement, SQL Server will not be able to give you last inserted identity value.
You cannot do it with the SQLQuery, even Hibernate uses JDBC to accomplish this task. I wrote a test on GitHub to emulate this and it works like this:
Session session = entityManager.unwrap(Session.class);
final AtomicLong resultHolder = new AtomicLong();
session.doWork(connection -> {
try(PreparedStatement statement = connection.prepareStatement("INSERT INTO post VALUES (?) select scope_identity() ") ) {
statement.setString(1, "abc");
if ( !statement.execute() ) {
while ( !statement.getMoreResults() && statement.getUpdateCount() != -1 ) {
// do nothing until we hit the resultset
}
}
try (ResultSet rs = statement.getResultSet()) {
if(rs.next()) {
resultHolder.set(rs.getLong(1));
}
}
}
});
assertNotNull(resultHolder.get());
The code uses Java 8 lambdas instead of anonymous classes, but you can easily port it to Java 1.7 too.

Get Hibernate Entity instance from id column in SQLQuery result

I have (non-Hibernated) database tables that contain ids for Hibernate entities. I can query them (using createSQLQuery), which gives me the ids, from which I can then load the entities.
I'd like to do that in one step, and I think I can do that with addEntity, but I am not sure how exactly. (Hibernate's documentation web site is down. Again.) I can use addEntity when all the columns for the entity table are present, but I have only the id now.
This complains about the missing columns:
return (List<MyEntity>) session.createSQLQuery(
"select entity_id from the_table where foreign_key_value = ?")
.addEntity("entity_id", MyEntity.class)
.setLong(0, foreignKey).list();
I think you want something like:
session.createSQLQuery("select {entity.*} from entity_table {entity} where ....")
.addEntity("entity", Entity.class).(bind-parameters).list();
Hibernate will expand "{entity.*}" to be the relevant columns from entity_table.
Although if you already have the IDs, you can simply use session.load() to convert those to actual instances (well, lazy-load proxies).
i would use a join
select *
from entity_table
where entity_id = (select entity_id
from non_hibernate_table
where id = ?)
For oracle dialect. If u have problem with mapping database column type to java data type u can set it manually like that: .addScalar("integerFieldName", Hibernate.INTEGER)
public class LookupCodeName
{
private String code;
private String name;
/*... getter-setters ... */
}
public class someBL {
public List<LookupCodeName> returnSomeEntity() {
SQLQuery sqlQuery = (SQLQuery)((HibernateSession)em).getHibernateSession()
.createSQLQuery( "SELECT st.name as name, st.code as code FROM someTable st")
.addScalar("code")
.addScalar("name")
.setResultTransformer(Transformers.aliasToBean(LookupCodeName.class));
}
return (List<LookupCodeName>)sqlQuery.list();
}

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