We Keep Coding

How to add optional column in JDBI?

I have big SQL, about 50 lines, and we use JDBI with Postgresql, and I need to add one additional not mandatory column, so I did:
,case when :byPortfolio is true then ia1.investmentAccountAbbreviationCode else null end as portfolio
so if :byPortfolio is true this column should be removed, and if false this column should be present. Also ia1.investmentAccountAbbreviationCode should be present in Group by clause if it's present, so I added:
,case when :byPortfolio2 is true then ia1.investmentAccountAbbreviationCode else null end
and it works if I fun it as SQL query, then I copied it to sql.stg template file for JDBI and now when I run it I see an exceptioin:
org.postgresql.util.PSQLException: ERROR: column "ia1.investmentaccountabbreviationcode" must appear in the GROUP BY clause or be used in an aggregate function
I don't understand why JDBI can't handle it. Function described like this:
#SqlQuery
#UseStringTemplateSqlLocator
#RegisterBeanMapper(SolutionOwnershipDataEntity.class)
List<SolutionOwnershipDataEntity> getSolutionOwnershipPercentageOfFundByDate(
#Bind("inputDate") String inputDate,
#Bind("fundSeriesId") Integer fundSeriesId,
#Bind("governanceCommitteeTypeCode") String governanceCommitteeTypeCode,
#Bind("byPortfolio") boolean byPortfolio,
#Bind("assetClass") String assetClass,
#Bind("vehicleType") String vehicleType);
Please help to fix it? We can fix current code or maybe there is other way to handle unnecessary column? I mean I can write two 50 lines SQL with same code, only difference would be presence or absence of one column, but I want to have one query with one unnecessary column, what is the best way to achieve this?

For byPortfolio, you need to use #Define instead of #Bind.
#Bind is only for binding values to parameters of a query, while #Define can be used for placeholders and templating.
For the templating, you can then put the optional parts between <if(byPortfolio)> and <endif>. The template syntax is not related to normal SQL.
Here is a complete example from the documentation:
#SqlQuery("""
select id, name
from account
order by <if(sort)> <sortBy>, <endif> id
""")
#UseStringTemplateEngine
List<Account> selectAll(#Define boolean sort, #Define String sortBy);
For more details, please have look at the official documentation: https://jdbi.org/#_stringtemplate_4

Less repetition in jOOQ query

Any idea on how I could define the following jOOQ query with less repetition?
I am using jOOQ 3.11.4.
db.insertInto(ACCOUNT,
ACCOUNT.ACCOUNT_ID,
ACCOUNT.EMAIL,
ACCOUNT.FIRST_NAME,
ACCOUNT.LAST_NAME,
ACCOUNT.IS_ADMIN,
ACCOUNT.PASSWORD)
.values(account.accountId,
account.email,
account.firstName,
account.lastName,
account.isAdmin,
account.password)
.onConflict(ACCOUNT.ACCOUNT_ID)
.doUpdate()
.set(ACCOUNT.EMAIL, account.email)
.set(ACCOUNT.FIRST_NAME, account.firstName)
.set(ACCOUNT.LAST_NAME, account.lastName)
.set(ACCOUNT.IS_ADMIN, account.isAdmin)
.set(ACCOUNT.PASSWORD, account.password)
.returning(
ACCOUNT.ACCOUNT_ID,
ACCOUNT.EMAIL,
ACCOUNT.FIRST_NAME,
ACCOUNT.LAST_NAME,
ACCOUNT.IS_ADMIN,
ACCOUNT.PASSWORD
)
.fetchOne()
(I turns out my question is mostly code, and StackOverflow does not let me post it as is, without adding more details, which I do not think is necessary for my question, but nevertheless, they want me to post some more text, which I am doing right now by typing this message, and I hope you did not have to read to the end.)

Since you're passing all the columns to the insert statement, you might write this instead:
// Create an AccountRecord that contains your POJO data
Record rec = db.newRecord(ACCOUNT);
rec.from(account);
// Don't pass the columns to the insert statement explicitly
db.insertInto(ACCOUNT)
// But pass the record to the set method. It will use all the changed values
.set(rec)
// Use the MySQL syntax, which can be emulated on PostgreSQL using ON CONFLICT
.onDuplicateKeyUpdate()
// But pass the record to the set method again
.set(rec)
// Don't specify any columns to the returning clause. It will take all the ACCOUNT columns
.returning()
.fetchOne();

How to check equality of spark columns after renaming

I am trying to write some tests for a Java Spark-Sql application. One operation I need to test renames a column, and I ran into some difficulty comparing the actual value of the renamed column with my expected value. After some experimentation, I was able to write the following two tests to demonstrate the problem:
First, as a sanity check, I tried this (df is a spark sql DataFrame, generated by reading some sample data from a json file I'm testing against):
#Test
public void testColumnEquality() throws Exception {
Column val1 = df.col("col2");
Column val2 = df.col("col2");
Assert.assertEquals(val1, val2);
}
Which passes, as one would expect. Then I tried this:
#Test
public void testReanmeColumnEquality() throws Exception {
Column val1 = df.col("col2").as("col2");
Column val2 = df.col("col2").as("col2");
Assert.assertEquals(val1, val2);
}
which fails with the error java.lang.AssertionError: expected:<col2 AS col2#4L> but was:<col2 AS col2#5L>
Digging around in the scala code (full disclosure - I know very little scala) it looks like this has to do with the NamedExpression unique id.
Is there any way to sensibly check that these two columns represent the same operations with the same alias?
(I'm working in spark 1.6, and would ideally like a solution for that version line, but if this is fixed in 2.0 that would also be good information.)
Thanks you.

I wrote a blog post about how to resolve this:
The trick is: check whether the Expression has the Alias trait:
`column.expr() instanceof Alias`
If it does, unpack the child expression and the name using the Extractor pattern:
alias = (Alias) column.expr()
Option<Tuple2<Expression, String>> aliasTuple = Alias$.MODULE$.unapply(alias);

I did some digging and it looks like the information about the child of a Column with an alias is lost in the process of instantiating the new Column. Maybe there is a state to query somewhere, but I didn't find it.
So it's not an answer, but hopefully it is useful or of interest to somebody.
more info
The definition of the as method on a Column object refers to the name function (see Column.scala), which just call the Alias case class defined here. The Alias (with its child), is not exposed. It is directly given to the Column class withExpr function which instantiate a new column based on the Alias named expression.
So you either compare directly the result of toString on the columns (loosing the information on where the column comes from, i.e. which dataframe), or you actually parse the string printed by the explain(true) method...but it doesn't seem sensible to me...

Spring Batch Paging with sortKeys and parameter values

I have a Spring Batch project running in Spring Boot that is working perfectly fine. For my reader I'm using JdbcPagingItemReader with a MySqlPagingQueryProvider.
#Bean
public ItemReader<Person> reader(DataSource dataSource) {
MySqlPagingQueryProvider provider = new MySqlPagingQueryProvider()
provider.setSelectClause(ScoringConstants.SCORING_SELECT_STATEMENT)
provider.setFromClause(ScoringConstants.SCORING_FROM_CLAUSE)
provider.setSortKeys("p.id": Order.ASCENDING)
JdbcPagingItemReader<Person> reader = new JdbcPagingItemReader<Person>()
reader.setRowMapper(new PersonRowMapper())
reader.setDataSource(dataSource)
reader.setQueryProvider(provider)
//Setting these caused the exception
reader.setParameterValues(
startDate: new Date() - 31,
endDate: new Date()
)
reader.afterPropertiesSet()
return reader
}
However, when I modified my query with some named parameters to replace previously hard coded date values and set these parameter values on the reader as shown above, I get the following exception on the second page read (the first page works fine because the _id parameter hasn't been made use of by the paging query provider):
org.springframework.dao.InvalidDataAccessApiUsageException: No value supplied for the SQL parameter '_id': No value registered for key '_id'
at org.springframework.jdbc.core.namedparam.NamedParameterUtils.buildValueArray(NamedParameterUtils.java:336)
at org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate.getPreparedStatementCreator(NamedParameterJdbcTemplate.java:374)
at org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate.query(NamedParameterJdbcTemplate.java:192)
at org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate.query(NamedParameterJdbcTemplate.java:199)
at org.springframework.batch.item.database.JdbcPagingItemReader.doReadPage(JdbcPagingItemReader.java:218)
at org.springframework.batch.item.database.AbstractPagingItemReader.doRead(AbstractPagingItemReader.java:108)
Here is an example of the SQL, which has no WHERE clause by default. One does get created automatically when the second page is read:
select *, (select id from family f where date_created between :startDate and :endDate and f.creator_id = p.id) from person p
On the second page, the sql is modified to the following, however it seems that the named parameter for _id didn't get supplied:
select *, (select id from family f where date_created between :startDate and :endDate and f.creator_id = p.id) from person p WHERE id > :_id
I'm wondering if I simply can't use the MySqlPagingQueryProvider sort keys together with additional named parameters set in JdbcPagingItemReader. If not, what is the best alternative to solving this problem? I need to be able to supply parameters to the query and also page it (vs. using the cursor). Thank you!

I solved this problem with some intense debugging. It turns out that MySqlPagingQueryProvider utilizes a method getSortKeysWithoutAliases() when it builds up the SQL query to run for the first page and for subsequent pages. It therefore appends and (p.id > :_id) instead of and (p.id > :_p.id). Later on, when the second page sort values are created and stored in JdbcPagingItemReader's startAfterValues field it will use the original "p.id" String specified and eventually put into the named parameter map the pair ("_p.id",10). However, when the reader tries to fill in _id in the query, it doesn't exist because the reader used the non-alias removed key.
Long story short, I had to remove the alias reference when defining my sort keys.
provider.setSortKeys("p.id": Order.ASCENDING)
had to change to in order for everything to work nicely together
provider.setSortKeys("id": Order.ASCENDING)

I had the same issue and got another possible solution.
My table T has a primary key field INTERNAL_ID.
The query in JdbcPagingItemReader was like this:
SELECT INTERNAL_ID, ... FROM T WHERE ... ORDER BY INTERNAL_ID ASC
So, the key is: in some conditions, the query didn't return results, and then, raised the error above No value supplied for...
The solution is:
Check in a Spring Batch decider element if there are rows.
If it is, continue with chunk: reader-processor-writer.
It it's not, go to another step.
Please, note that they are two different scenarios:
At the beginning, there are rows. You get them by paging and finally, there are no more rows. This has no problem and decider trick is not required.
At the beginning, there are no rows. Then, this error raised, and the decider solved it.
Hope this helps.

Can I get the string from preparedStatem.setString()?

I have a problem - I create my SQL queries dynamically and basing on user input options. So the user has 5 parameters (actually it's more) and he can choose to use some of them (all if he wants) or none and specify their value in the query. So I construct my query String (basic the WHERE conditions) by checking if a parameter was selected and if a value was provided. However now there is the problem of special characters like '. I could try to use replaceAll("'", "\\") but this is quite dull and I know that preparedStatement.setString() does the job better. However for me I would need than to check again if the parameter was provided and if the previous one were also (to specify the poison of ? and connect it to the right parameter). This causes a lot of combinations and does not look elegant.
So my question is - can I somehow receive the string preparedStatement.setString() produces? Or is there a similar function that would do the same job and give me the String so I can put it in the query manually.
Maybe the intro was too long but someone might have a better idea and I wanted to explain why I need it.

What you can do is construct the basic, unparameterized SQL query based on whether the parameters were specified, and then use the prepared statement to fill in the parameters.
It could look something like this (rough sketch):
Map<String, Object> parameterValues = /*from user*/;
List<String> parameterNames = Arrays.asList("field1", "field2", "field3");
List<Object> valueList = new ArrayList<Object>();
StringBuilder statementBuilder = new StringBuilder("select * from table where ");
for ( String parameterName : parameterNames ) {
if ( parameterValues.containsKey(parameterName) ) {
statementBuilder.append(parameterName + " = ? AND");
valueList.add(parameterValues.get(parameterName));
}
}
PreparedStatement st = conn.prepareStatement(statementBuilder.toString(),
valueList);
//set each parameter here.
It's only hard the first time; then you can make it generic. That said there are probably query builders that abstract all of this away for you. I use QueryDSL but that does not have bindings for pure JDBC but rather JPA and JDO, etc.

On another forum I was given a different, simpler and cleaner approach that work perfectly.
Here are some links for others with the same problem:
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1669972300346534908
http://www.akadia.com/services/dyn_modify_where_clause.html