[SPARK-6967] [SQL] fix date type convertion in jdbcrdd

[adrian-wang]

This pr convert java.sql.Date type into Int for JDBCRDD.

[SparkQA]

Test build #30581 has finished for PR 5590 at commit 3c9184c.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.
• This patch does not change any dependencies.

[marmbrus]

Could we add a unit test in JDBCSuite?

[SparkQA]

Test build #30727 has finished for PR 5590 at commit f897b81.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.
• This patch does not change any dependencies.

[rxin]

Merging in master and branch-1.3.

[nadavoosh]

hi @adrian-wang ! I am using spark and needed to include this fix, since I am reading from a table that has Date types. I rebuilt spark with this change & it works well.

I just ran into a new problem though: when the Date field has null values, spark throws a java.lang.NullPointerException
at org.apache.spark.sql.types.DateUtils$.javaDateToDays(DateUtils.scala:39)
error. Any ideas on how I can fix that?

Thank you for your help!

[adrian-wang]

@nadavoosh Thanks for your feedback! I will take a look at this soon.

[nadavoosh]

@adrian-wang this worked for me:

 case DateConversion => {
val x = rs.getDate(pos)
mutableRow.update(i, if (x == null) null else DateUtils.fromJavaDate(x) )
}
case DecimalConversion => {
val x = rs.getBigDecimal(pos)
mutableRow.update(i, if (x == null) null else Decimal(x) )
}