Add INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS from the SQL standard

h2/src/main/org/h2/table/MetaTable.java

@@ -112,7 +112,8 @@ public class MetaTable extends Table {
     private static final int SYNONYMS = 29;
     private static final int TABLE_CONSTRAINTS = 30;
     private static final int KEY_COLUMN_USAGE = 31;
-    private static final int META_TABLE_TYPE_COUNT = KEY_COLUMN_USAGE + 1;
+    private static final int REFERENTIAL_CONSTRAINTS = 32;
+    private static final int META_TABLE_TYPE_COUNT = REFERENTIAL_CONSTRAINTS + 1;
 
     private final int type;
     private final int indexColumn;
@@ -591,6 +592,21 @@ public class MetaTable extends Table {
             indexColumnName = "TABLE_NAME";
             break;
         }
+        case REFERENTIAL_CONSTRAINTS: {
+            setObjectName("REFERENTIAL_CONSTRAINTS");
+            cols = createColumns(
+                    "CONSTRAINT_CATALOG",
+                    "CONSTRAINT_SCHEMA",
+                    "CONSTRAINT_NAME",
+                    "UNIQUE_CONSTRAINT_CATALOG",
+                    "UNIQUE_CONSTRAINT_SCHEMA",
+                    "UNIQUE_CONSTRAINT_NAME",
+                    "MATCH_OPTION",
+                    "UPDATE_RULE",
+                    "DELETE_RULE"
+            );
+            break;
+        }
         default:
             throw DbException.throwInternalError("type="+type);
         }
@@ -2025,6 +2041,41 @@ public class MetaTable extends Table {
             }
             break;
         }
+        case REFERENTIAL_CONSTRAINTS: {
+            for (SchemaObject obj : database.getAllSchemaObjects(DbObject.CONSTRAINT)) {
+                if (((Constraint) obj).getConstraintType() != Constraint.Type.REFERENTIAL) {
+                    continue;
+                }
+                ConstraintReferential constraint = (ConstraintReferential) obj;
+                Table table = constraint.getTable();
+                if (hideTable(table, session)) {
+                    continue;
+                }
+                Index index = constraint.getUniqueIndex();
+                add(rows,
+                        // CONSTRAINT_CATALOG
+                        catalog,
+                        // CONSTRAINT_SCHEMA
+                        identifier(constraint.getSchema().getName()),
+                        // CONSTRAINT_NAME
+                        identifier(constraint.getName()),
+                        // UNIQUE_CONSTRAINT_CATALOG
+                        catalog,
+                        // UNIQUE_CONSTRAINT_SCHEMA
+                        identifier(index.getSchema().getName()),
+                        // UNIQUE_CONSTRAINT_NAME
+                        // Should be name of referenced unique constraint, but H2 uses indexes instead
+                        index.getName(),
+                        // MATCH_OPTION
+                        "NONE",
+                        // UPDATE_RULE
+                        constraint.getUpdateAction().getSqlName(),
+                        // DELETE_RULE
+                        constraint.getDeleteAction().getSqlName()
+                );
+            }
+            break;
+        }
         default:
             DbException.throwInternalError("type="+type);
         }

h2/src/test/org/h2/test/jdbc/TestMetaData.java

@@ -1090,6 +1090,8 @@ public class TestMetaData extends TestBase {
         rs.next();
         assertEquals("QUERY_STATISTICS", rs.getString("TABLE_NAME"));
         rs.next();
+        assertEquals("REFERENTIAL_CONSTRAINTS", rs.getString("TABLE_NAME"));
+        rs.next();
         assertEquals("RIGHTS", rs.getString("TABLE_NAME"));
         rs.next();
         assertEquals("ROLES", rs.getString("TABLE_NAME"));

h2/src/test/org/h2/test/scripts/information_schema.sql

@@ -15,7 +15,7 @@ ALTER TABLE T1 ADD CONSTRAINT U_1 UNIQUE(C3, C4);
 CREATE TABLE T2(C1 INT, C2 INT, C3 INT, C4 INT);
 > ok
 
-ALTER TABLE T2 ADD CONSTRAINT FK_1 FOREIGN KEY (C3, C4) REFERENCES T1(C1, C3);
+ALTER TABLE T2 ADD CONSTRAINT FK_1 FOREIGN KEY (C3, C4) REFERENCES T1(C1, C3) ON DELETE SET NULL;
 > ok
 
 ALTER TABLE T2 ADD CONSTRAINT CH_1 CHECK C4 > 0;
@@ -55,6 +55,20 @@ SELECT CONSTRAINT_NAME, TABLE_NAME, COLUMN_NAME, ORDINAL_POSITION, POSITION_IN_U
 > FK_1            T2         C4          2                2
 > rows (ordered): 6
 
+SELECT * FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS LIMIT 0;
+> CONSTRAINT_CATALOG CONSTRAINT_SCHEMA CONSTRAINT_NAME UNIQUE_CONSTRAINT_CATALOG UNIQUE_CONSTRAINT_SCHEMA UNIQUE_CONSTRAINT_NAME MATCH_OPTION UPDATE_RULE DELETE_RULE
+> ------------------ ----------------- --------------- ------------------------- ------------------------ ---------------------- ------------ ----------- -----------
+> rows: 0
+
+-- H2 returns name of the index istead of name of the referenced constraint as UNIQUE_CONSTRAINT_NAME
+SELECT CONSTRAINT_NAME, SUBSTRING(UNIQUE_CONSTRAINT_NAME, 0, 11) AS UCN_PART, MATCH_OPTION, UPDATE_RULE, DELETE_RULE FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS
+    WHERE CONSTRAINT_CATALOG = DATABASE() AND CONSTRAINT_SCHEMA = SCHEMA() AND UNIQUE_CONSTRAINT_CATALOG = DATABASE() AND UNIQUE_CONSTRAINT_SCHEMA = SCHEMA()
+    ORDER BY CONSTRAINT_NAME, UNIQUE_CONSTRAINT_NAME;
+> CONSTRAINT_NAME UCN_PART    MATCH_OPTION UPDATE_RULE DELETE_RULE
+> --------------- ----------- ------------ ----------- -----------
+> FK_1            FK_1_INDEX_ NONE         RESTRICT    SET NULL
+> rows (ordered): 1
+
 DROP TABLE T2;
 > ok