I have finally found out that my understanding of JOIN in MySQL is not yet other one that should be in Derby:

select SYS.SYSCONSTRAINTS.*, SYS.SYSCOLUMNS.COLUMNNAME from SYS.SYSCONSTRAINTS right outer join SYS.SYSCOLUMNS on SYS.SYSCONSTRAINTS.TABLEID = SYS.SYSCOLUMNS.REFERENCEID;

I wanted to force L-/R- JOINs to properly be interpreted. And got this:

CONSTRAINTID š š š š š š š š š š š š|TABLEID š š š š š š š š š š š š š š |CONSTRAINTNAME š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|TYPE š š š š š š|SCHEMAID š š š š š š š š š š š š š š|STA& š š |REFERENCEC&|COLUMNNAME š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š
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NULL š š š š š š š š š š š š š š š š š š š š š|NULL š š š š š š š š š š š š š š š š|NULL š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|NULL š š š š š š š |NULL š š š š š š š š š š š š š š š š|NUL š š L|NULL š š š |ISDEF š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š šš
cbf5809d-0127-df6f-bee8-000000547e10|2ba7c09b-0127-df6f-bee8-000000547e10|SQL100409011100670 š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|P š |80000000-00d2-b38f-4cda-000a0a412c00|E š |1 š š š š š|ID š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š
cbf5809d-0127-df6f-bee8-0000005|2ba7c09b-0127-df6f-bee8-000000547e10|SQL100409011100670 š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š |P š |80000000-00d2-b38f-4cda-000a0a412c00|E š |1 š š š š š|NAME š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š
e50d80a4-0127-df6f-bee8-000000547e102-0127-df6f-bee8-000000547e10|SQL100409011755320 š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|P š |80000000-00d2-b38f-4cda-000a0a412c00|E š |0 š š š š š|RECORD_ID š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š šš
4d3680a5-0127-df6f-bee8-000000547e10|94bc40af6f-bee8-000000547e10|SQL100409011755321 š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|F š |80000000-00d2-b38f-4cda-000a0a412c00|E š |0 š š š š š|RECORD_ID š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š šš
e50d80a4-0127-df6f-bee8-000000547e10|94bc40a2-0127-d-000000547e10|SQL100409011755320 š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|P š |80000000-00d2-b38f-4cda-000a0a412c00|E š |0 š š š š š|SHUTDOWN_TYPE š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š šš
4d3680a5-0127-df6f-bee8-000000547e10|94bc40a2-0127-df6f-bee847e10|SQL100409011755321 š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|F š |80000000-00d2-b38f-4cda-000a0a412c00|E š |0 š š š š š|SHUTDOWN_TYPE š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š šš
e50d80a4-0127-df6f-bee8-000000547e10|94bc40a2-0127-df6f-bee8-0000005L100409011755320 š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|P š |80000000-00d2-b38f-4cda-000a0a412c00|E š |0 š š š š š|ADMIN_RECORDS š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š šš
4d3680a5-0127-df6f-bee8-000000547e10|94bc40a2-0127-df6f-bee8-000000547e10|SQ11755321 š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|F š |80000000-00d2-b38f-4cda-000a0a412c00|E š |0 š š š š š|ADMIN_RECORDS š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š šš
NULL š š š š š š š š š š š š š š š š|NULL š š š š š š š š š š š š š š š š|NULL š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|NULL|NULL š š š š š š š š š š š š š š š š|NULL|NULL š š š |PARAM1

Hence NULLs all over the places before and after some main records. So R-JOINs works as expected.

I tried to correctly collect column-per-table pairs;

select SYS.SYSCOLUMNS.COLUMNNAME, SYS.SYSTABLES.TABLENAME from SYS.SYSCOLUMNS, SYS.SYSTABLES, SYS.SYSCONSTRAINTS where SYS.SYSTABLES.TABLEID = SYS.SYSCOLUMNS.REFERENCEID and SYS.SYSTABLES.TABLENAME like 'SERVER%' and not SYS.SYSTABLES.TABLEID=SYS.SYSCONSTRAINTS.TABLEID;
COLUMNNAME š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|TABLENAME š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š šš
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ADMIN_RECORDS š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š |SERVER_SHUTDOWN_LOG š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š šš
RECORD_ID š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š |SERVER_SHUTDOWN_LOG š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š šš
SHUTDOWN_TYPE š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š |SERVER_SHUTDOWN_LOG š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š šš
ID š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|SERVER_SHUTDOWN_TYPE š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š
NAME š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|SERVER_SHUTDOWN_TYPE š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š
ID š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|SERVER_SHUTDOWN_TYPE š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š
NAME š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|SERVER_SHUTDOWN_TYPE š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š

That worked fine. No duplicates...

That two tables appear in SYSCONSTRAINTS:

select SYS.SYSCONSTRAINTS.TABLEID from SYS.SYSCONSTRAINTS;
TABLEID š š š š š š š š š š š š š šš
------------------------------------
2ba7c09b-0127-df6f-bee8-000000547e10
94bc40a2-0127-df6f-bee8-000000547e10
94bc40a2-0127-df6f-bee8-000000547e10

So:

SELECT CONSTRAINTNAME, COLUMNNAME FROM SYS.SYSTABLES t, SYS.SYSCOLUMNS col, SYS.SYSCONSTRAINTS cons, SYS.SYSCHECKS checks WHERE t.TABLENAME like 'SERVER%' AND t.TABLEID = col.REFERENCEID AND t.TABLEID = cons.TABLEID AND cons.CONSTRAINTID = checks.CONSTRAINTID ORDER BY CONSTRAINTNAME;
CONSTRAINTNAME š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|COLUMNNAME š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š
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๗ูยามฮฯ ำิาฯห: 0
ij> SELECT CONSTRAINTNAME, COLUMNNAME FROM SYS.SYSTABLES t, SYS.SYSCOLUMNS col, SYS.SYSCONSTRAINTS cons, SYS.SYSCHECKS checks where t.TABLEID = col.REFERENCEID AND t.TABLEID = cons.TABLEID AND cons.CONSTRAINTID = checks.CONSTRAINTID ORDER BY CONSTRAINTNAME;
CONSTRAINTNAME š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š|COLUMNNAME š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š š
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๗ูยามฮฯ ำิาฯห: 0

But again - I do not see rows because constraints not appear to be mapped to columns. John