Make it recognize not null constraints and set type to Unknown when the value is not recognized.

Note column not null constraints where not stored in pg_constraint before postgresl 18

pglablib/catalog/PgConstraint.cpp

@@ -24,6 +24,12 @@ void operator<<(ConstraintType &s, const Pgsql::Value &v)
 	case 'x':
 		s = ConstraintType::ExclusionConstraint;
 		break;
+    case 'n':
+        s = ConstraintType::NotNull;
+        break;
+    default:
+        s = ConstraintType::Unknown;
+        break;
 	}
 }
 
@@ -49,7 +55,10 @@ QString ShortNameForConstraintType(ConstraintType ct)
 	case ConstraintType::ExclusionConstraint:
 		s = "XC";
 		break;
-	default:
+    case ConstraintType::NotNull:
+        s = "NN";
+        break;
+    default:
 		s = "?";
 		break;
 	}
@@ -78,6 +87,9 @@ QString LongNameForConstraintType(ConstraintType ct)
 	case ConstraintType::ExclusionConstraint:
 		s = "exclusion constraint";
 		break;
+    case ConstraintType::NotNull:
+        s = "not null";
+        break;
 	default:
 		s = "?";
 		break;

pglablib/catalog/PgConstraint.h

@@ -11,12 +11,14 @@
 #include <vector>
 
 enum class ConstraintType {
+    Unknown, // not recognized, new???
 	PrimaryKey, // p
 	ForeignKey, // f
 	Unique, // u
 	Check,  // c
 	ConstraintTrigger, // t
 	ExclusionConstraint, // x
+    NotNull, // n
 };
 
 void operator<<(ConstraintType &s, const Pgsql::Value &v);