I'm using JDBC, I have to set array of values to a single column,
I know it works in Hibernate and Ibatis but it seems to be hard to get it working Pure JDBC sql.
I have an array of String values
names[] = new String[]{"A","B","C"};
and a Query like
select * from emp where name in(?)
I tried pstmt.setObject(1,names), it is not working..
This is not supported in pure JDBC. You have to generate a query so that the in clause contains one placeholder for each element of the array.
Spring's JDBC helper classes support named parameters and what you want to do.
This will work with the following Syntax:
"SELECT * FROM emp WHERE name IN ( SELECT column_value FROM TABLE( ? ) )"
pmst.setArray( 1, conn.createArrayOf( "VARCHAR", names ) );
Related
I am just wondering if use = sign operator with sub-query instead of IN
Is it correct way ? and meet the oracle standard ?
Example
select column_name from my_table_1 where id = (select max(id) from my_table_2);
The Difference is related to the number of rows returned. If you have only one row returned from nested sql you may prefer both = or in operators. But if multiple rows returned from nested query, use in operator.
So, in your sql example you may prefer using any of the operators. Since, max functions returns only one row.
As you are fetching maximum value from subquery to compare with id, Both(= and IN )will work fine. But If you are trying to fetch more than one row then you have to use IN keyword.
If you have 1 result in sub query you are fine with using = sign, except when data type is wrong, for example , checking with same data type of dummy VARCHAR2(1)
select * from dual where 'X' = (select max(dual.dummy) from dual);
Is similar to using in (also same explain plain)
select * from dual where 'X' in (select max(dual.dummy) from dual);
But checking with different/wrong data type will result with exception ORA-01722 Invalid number
select * from dual where 1 =(select max(dual.dummy) from dual);
I have the following query where the first argument itself is a subquery
The java code is:
String query = select * from (?) where ROWNUM < ?
PreparedStatement statement = conn.preparedStatement(query)
statement.setString(1, "select * from foo_table")
statement.setInt(2, 3)
When I run the java code, I get an exception. What alternatives do I have for making the first subquery statement.setString(1, "select * from foo_table") a parameter?
This is not possible, parameter placeholders can only represent values, not object names (like table names, column names, etc) nor subselects or other query elements.
You will need to dynamically create the query to execute using string concatenation, or other string formatting/templating options.
In JDBC To Other Databases I found the following explanation of dbtable parameter:
The JDBC table that should be read. Note that anything that is valid in a FROM clause of a SQL query can be used. For example, instead of a full table you could also use a subquery in parentheses.
When I use the code:
CREATE TEMPORARY TABLE jdbcTable
USING org.apache.spark.sql.jdbc
OPTIONS (
url "jdbc:postgresql:dbserver",
dbtable "mytable"
)
everything works great, but the following:
dbtable "SELECT * FROM mytable"
leads to the error:
What is wrong?
Since dbtable is used as a source for the SELECT statement it has be in a form which would be valid for normal SQL query. If you want to use subquery you should pass a query in parentheses and provide an alias:
CREATE TEMPORARY TABLE jdbcTable
USING org.apache.spark.sql.jdbc
OPTIONS (
url "jdbc:postgresql:dbserver",
dbtable "(SELECT * FROM mytable) tmp"
);
It will be passed to the database as:
SELECT * FROM (SELECT * FROM mytable) tmp WHERE 1=0
Code In Scala
val checkQuery = "(SELECT * FROM " + inputTableName + " ORDER BY " + columnName + " DESC LIMIT 1) AS timetable"
val timeStampDf = spark.read.format("jdbc").option("url", url).option("dbtable", checkQuery).load()
Adding an alias is also necessary after the query in parenthesis.
While Hive doesn't supports multi-value LIKE queries which are supported in SQL : ex.
SELECT * FROM user_table WHERE first_name LIKE ANY ( 'root~%' , 'user~%' );
We can convert it into equivalent HIVE queries as :
SELECT * FROM user_table WHERE first_name LIKE 'root~%' OR first_name LIKE 'user~%'
Does anyone know an equivalent solution that Hive does support in case sub-query is used with LIKE ? Have a look at below example :
SELECT * FROM user_table WHERE first_name LIKE ANY ( SELECT expr FROM exprTable);
As It doesn't have values in expression, I can't use same approach for generating multiple LIKE expression separated with OR / AND operator. Initially I thought to write HIVE UDF for it ? Can you please help me supporting such expression and finding HIVE equivalent ?
You can use Hive's RLIKE relational operator as shown below,
SELECT * FROM user_table WHERE first_name RLIKE 'root~|user~|admin~';
Hope this helps!
This is a case involving theta joins in Hive. There is a wiki page for this and a jira request. Please go through the details here on this page: https://cwiki.apache.org/confluence/display/Hive/Theta+Join
Your case is similar to the Side-Table Similarity case given on the page.
You need to convert the expr values into a map and then use regular expression to find the like. Alternatively you can also use union all with all the like expressions in separate SQL - the query might become tedious so you can programatically generate it.
What about this using EXISTS
SELECT * FROM user_table WHERE EXISTS ( SELECT * FROM exprTable WHERE first_name LIKE expr );
I would like to achieve same result as the below query using Hibernate SQL, i.e., I would like to get two random records from the table whose ID is not equal to 300. I am using Hibernate 4.1 and Oracle 11g. I ran the below query on Toad and it gives 2 random records. But, when I try to run the HQL, there is error to do with the usage of "DBMS_RANDOM.value".
SELECT * FROM
( SELECT *
FROM table
where ID != '300'
AND q_ID=125
ORDER BY DBMS_RANDOM.value
)WHERE rownum < 3
;
I tried creating criteria and query, but both give Hibernate errors:
Hibernate Message: Invalid path: 'DBMS_RANDOM.RANDOM' [from com.model.table tab where tab.ID != '33092' ORDER BY DBMS_RANDOM.RANDOM]
and my actual hibernate query is:
Query query = session.createQuery("from table tab where tab.ID != '" +agrmId+"' ORDER BY DBMS_RANDOM.RANDOM").setMaxResults(2);
I also tried ORDER BY rand() and that gives an Oracle error.
Thank you for any help.
I solved the problem by adding a property tag in the hibernate mapping file:
<property name="constVal" formula="DBMS_RANDOM.RANDOM" type="long"/>
and then, in the POJO class, I added a variable with getter and setter methods:
private long constVal;
then, in the DAO class, I added the following query:
Criteria crit1 = session.createCriteria(table.class);
crit1.add(Restrictions.ne("id",300));
crit1.add(Restrictions.eq("quesId",125));
crit1.addOrder(Order.asc("constVal"));
crit1.setMaxResults(2);
and that solved it.