To unfreeze:

• Do $SYSTEM.SQL.FreezePlans(0,1,,.Errors) // Unfreezes all SQL statement plans in the current namespace
• Do $SYSTEM.SQL.FreezePlans(2,1,,.Errors) // Unfreezes all SQL statement plans in the current namespace that were marked Frozen/Upgrade.

Then execute $system.SQL.Purge()

That should unfreeze everything and delete all CQs.

The noted difference between %SQL.StatementResult.%Get() and %Library.ResultSet.%Get() is regarding the actual column names, not the values they contain.

Given that I am using InterSystems IRIS, but here is how I reproduced your example (I don't use a left-join, but they should behave the same)

CREATE TABLE testTable("Column A" INT, "Column B" INT, "Column C" INT, "Column D" INT)
INSERT INTO testTable VALUES(1,2,3,4)
INSERT INTO testTable VALUES(1 NULL, NULL,4)

-------------------------

USER>set stmt = ##class(%SQL.Statement).%New()
USER>set query = 1, query(1) = "SELECT * FROM testTable"
USER>write stmt.%Prepare(.query)
1
USER>set rs = stmt.%Execute()
USER>write rs.%Next()
1
USER>write rs.%Get("Column B")
2
USER>write rs.%Next()
1
USER>zwrite rs.%Get("Column B")
""

USER>do $system.Status.DisplayError(rs.%Get("Column E"))
 
DO $SYSTEM.Status.DisplayError(rs.%Get("Column E"))
^
<PROPERTY DOES NOT EXIST> *Column E,%sqlcq.USER.cls15

As you can see, %SQL.StatementResult.%Get() should only throw an error if you pass in an invalid column name such as "Column E" in the code snippet above.

I recommend that you check the %SQL.StatementMetadata to check if the columns exist in the first place.

USER>set rsmd = rs.%GetMetadata()
USER>set columns = $LB()
USER>for i=0:1:rsmd.columnCount-1 set $li(columns,i+1)=rsmd.columns.GetNext(i).colName

Once you have columns populated, you can use $LISTFIND to determine whether or not the column exists.

If you cannot do the above then you can wrap the use of %SQL.StatementResult.%Get() with a try-catch block as seen below:

while(rs.%Next()) {
     try {
         set var = rs.%Get(columnName)
     } catch {
         set var = ""
     }
}

I do not recommend the try-catch fallback assignment

If you have a java.sql.PreparedStatement and what seems to be a java.io.InputStream subclass (since you can call read() on it), why not utilize java.sql.PreparedStatement.setBinaryStream(int parameterIndex, InputStream x)? I am not sure which version of com.intersys.jdbc.CacheDriver you are using, but it is likely that your driver version has that API supported.

try (
    java.sql.Connection        cnxn  = DriverMasnager.getConnection(url, cnxnProps);
    java.sql.PreparedStatement pstmt = cnxn.prepareStatement(
            "INSERT INTO tableWithBlobField VALUES(?)");
){
    pstmt.setBinaryStream(1, binaryStreamFromRestAPI);
    pstmt.executeUpdate();
}