LibSQL: Added 'nullable' and 'default value' option to ColumnDef

These are standard SQL concepts which columns should be aware of.

Userland/Libraries/LibSQL/Meta.cpp

@@ -46,6 +46,7 @@ ColumnDef::ColumnDef(Relation* parent, size_t column_number, String name, SQLTyp
     : Relation(move(name), parent)
     , m_index(column_number)
     , m_type(sql_type)
+    , m_default(Value(sql_type))
 {
 }
 
@@ -59,6 +60,12 @@ Key ColumnDef::key() const
     return key;
 }
 
+void ColumnDef::set_default_value(const Value& default_value)
+{
+    VERIFY(default_value.type() == type());
+    m_default = default_value;
+}
+
 Key ColumnDef::make_key(TableDef const& table_def)
 {
     Key key(index_def());

Userland/Libraries/LibSQL/Meta.h

@@ -74,6 +74,11 @@ public:
     Key key() const override;
     SQLType type() const { return m_type; }
     size_t column_number() const { return m_index; }
+    void set_not_null(bool can_not_be_null) { m_not_null = can_not_be_null; }
+    bool not_null() const { return m_not_null; }
+    void set_default_value(Value const& default_value);
+    Value const& default_value() const { return m_default; }
+
     static NonnullRefPtr<IndexDef> index_def();
     static Key make_key(TableDef const&);
 
@@ -83,6 +88,8 @@ protected:
 private:
     size_t m_index;
     SQLType m_type { SQLType::Text };
+    bool m_not_null { false };
+    Value m_default;
 };
 
 class KeyPartDef : public ColumnDef {